scholarly journals 47 Tertiary lymphoid structures (TLS) in desmoplastic melanomas (DM) differ from non-DM-associated TLS by their intratumoral location and enhanced immune activity

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A54-A54
Author(s):  
Ileana Mauldin ◽  
Anne Stowman ◽  
Alexandra Hickman ◽  
Adela Mahmutovic ◽  
Alejandro Gru ◽  
...  

BackgroundTertiary lymphoid structures (TLS) are ectopic lymphoid organs that are localized near tumors and other sites of inflammation, and are commonly believed to support antitumor immunity. We previously published studies that show that most desmoplastic melanomas contain TLS, and that TLS in cutaneous metastatic melanomas varied widely in maturation state, in proportions of proliferating T and B cells, and in markers of B cell function, including AID and CD21. Thus, we hypothesized that there may be diversity in TLS function, or immunologic activity, among melanomas. To address this hypothesis, we evaluated TLS in primary desmoplastic melanomas (DM), and non-desmoplastic melanomas (non-DM) for markers of cell proliferation which are indicative of early immune activity.MethodsDM and non-DM tumor specimens, which included primary melanomas (PM), and cutaneous metastatic melanomas (CMM), were evaluated for TLS by multiplex Immunofluorescence histology, by staining for CD20, CD8, PNAd, Ki67, FoxP3, and DAPI. Lymphoid aggregates were identified in 20x spectrally unmixed images by visual inspection and identified as TLS if possessing organized T-cell and B-cell regions in addition to high endothelial venule-like vasculature (PNAd+). TLS were identified in 30 out of 64 screened (48%) CMM, 4/4 non-DM PM, and 8 out of 11 screened (73%) DM. Immune cells localized in TLS were enumerated using Halo software (Indica Labs). Mann-Whitney tests were used for statistical assessments.ResultsDM commonly contain a dense network of fibroblasts and associated stroma, which are not typical for other non-DM (PM and CMM). TLS in DM are located throughout the tumors, intratumorally, in sharp distinction from the peritumoral location of TLS in non-DM. Furthermore, when compared to TLS of non-DM (PM and CMM), TLS of DM contain increased densities of CD20+ B cells (PM p=0.007; CMM p<0.0001) and CD8+ T cells (PM p=0.017; CMM p=0.0006), and a higher proportion of proliferating (Ki67+) CD20+ B cells (PM p=0.04; CMM p=0.009).ConclusionsRecently published studies have identified tumor-associated fibroblasts as the likely initiating cells for TLS formation in murine melanomas. The intratumoral location of TLS in DM puts them in close proximity to the dense fibroblasts and desmoplastic stroma in these tumors, which may be responsible for their intratumoral location. The increased density of B and T cells, and higher proportion of proliferating (Ki67+) B cells, in DM than in non-DM, suggests that there may be greater immune activation, increased germinal center maturation, or less regulation in TLS of DM.Ethics ApprovalApproval was obtained for these studies under IRB protocol #’s 10598 and 19694.

2021 ◽  
Vol 12 ◽  
Author(s):  
Marta Trüb ◽  
Alfred Zippelius

Tertiary lymphoid structures (TLS) are ectopic lymphoid formations which are formed under long-lasting inflammatory conditions, including tumours. TLS are composed predominantly of B cells, T cells and dendritic cells, and display various levels of organisation, from locally concentrated aggregates of immune cells, through clearly defined B cell follicles to mature follicles containing germinal centres. Their presence has been strongly associated with improved survival and clinical outcome upon cancer immunotherapies for patients with solid tumours, indicating potential for TLS to be used as a prognostic and predictive factor. Although signals involved in TLS generation and main cellular components of TLS have been extensively characterised, the exact mechanism by which TLS contribute to the anti-tumour response remain unclear. Here, we summarise the most recent development in our understanding of their role in cancer and in particular in the response to cancer immunotherapy. Deciphering the relationship between B cells and T cells found in TLS is a highly exciting field of investigation, with the potential to lead to novel, B-cell focused immunotherapies.


2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A572-A572
Author(s):  
Ayana Ruffin ◽  
Anthony Cillo ◽  
Tracy Tabib ◽  
Angen Liu ◽  
Sayali Onkar ◽  
...  

BackgroundCurrent FDA-approved immunotherapies aim to reinvigorate CD8+ T cells, but the contribution of the humoral arm of the immune response in human cancer remains poorly understood. B cells within tissues can mediate anti-tumor immunity and regulate immune responses by presenting antigen and producing tumor-specific antibodies and immunomodulatory cytokines. Head and neck squamous cell carcinoma (HNSCC) can be induced by human papillomavirus (HPV+) and carcinogens such as tobacco and alcohol (HPV-), and the immune infiltrate is quite distinct in the two etiologies, in particular, increased B cells in HPV+ HNSCC patients. Further, increased B cells in HNSCC patients correlate with improved patient survival. Our study seeks to differentiate B cell phenotype, function and location in HPV+ and HPV- HNSCC to identify putative B cell-centric immunotherapeutic targets.MethodsWe utilized a multi-level approach to clearly categorize B cells in HNSCC patients. Single cell RNA sequencing (scRNAseq) was performed on CD45+ tumor infiltrating lymphocytes (TIL) from HPV+ and HPV- HNSCC patients. HNSCC TIL and PBL were stained via spectral cytometry (Cytek Aurora,25 parameters) for unbiased analysis of B cell subsets via computational spectral unmixing. Paraffin embedded slides from HNSCC primary tumors were utilized for multispectral immunofluorescence (mIF) to identify tertiary lymphoid structures (TLS) and identify differences in HPV+ and HPV- disease.ResultsWe demonstrated distinct trajectories for B cells in HPV+ and HPV- disease. HPV- HNSCC tumors mainly contained memory B cells and plasma cells, while the B cells in HPV+ HNSCC were naïve and germinal center (GC). Further, we quantified B cells and CD4+ T cells in TLS, and germinal center-like TLS were associated with improved outcome in HPV+ disease. We also observed that transcriptional and protein expression of Semaphorin A (SEMA4a) was restricted to GC B cells and increased on GC B cells in HNSCC patients compared to healthy tonsils. Additionally, we identified distinct waves of gene expression in GC B cells in HNSCC tumors, ultimately revealing a novel transitional state for GC B cells in the tumor microenvironment (TME).ConclusionsUnderstanding B cell function in human cancers and how different TMEs influence B cells and TLS are important for devising novel therapeutic options for cancer patients. Ultimately, development of therapeutics to enhance B cell responses in the TME should be prioritized as a compliment to T-cell mediated therapies.


1980 ◽  
Vol 152 (5) ◽  
pp. 1274-1288 ◽  
Author(s):  
P Marrack ◽  
J W Kappler

The mode of action by bystander helper T cells was investigated by priming (responder X nonresponder) (B6A)F1 T cells with poly-L-(Tyr, Glu)-poly-D,L-Ala--poly-L-Lys [(TG)-A--L] and titrating the ability of these cells to stimulate an anti-sheep red blood cell (SRBC) response of parental B cells and macrophages in the presence of (TG)-A--L. Under limiting T cell conditions, and in the presence of (TG)-A--L, (TG)-A--L-responsive T cells were able to drive anti-SRBC responses of high-responder C57BL/10.SgSn (B10) B cells and macrophages (M0), but not of low-responder (B10.A) B cells and M0. Surprisingly, the (TG)-A--L-driven anti-SRBC response of B10.A B cells was not restored by addition of high-responder acessory cells, in the form of (B6A)F1 peritoneal or irradiated T cell-depleted spleen cells, or in the form of B10 nonirradiated T cell-depleted spleen cells. These results suggested that (TG)-A--L-specific Ir genes expressed by B cells controlled the ability of these cells to be induced to respond to SRBC by (TG)-A--L-responding T cells, implying that direct contact between the SRBC-binding B cell precursor and the (TG)-A--L-responsive helper T cells was required. Analogous results were obtained for keyhold limpet hemocyanin (KLH)-driven bystander help using KLH-primed F1 T cells restricted to interact with cells on only one of the parental haplotypes by maturing them in parental bone marrow chimeras. It was hypothesized that bystander help was mediated by nonspecific uptake of antigen [(TG)-A--L or KLH] by SRBC-specific b cells and subsequent display of the antigen on the B cell surface in association with Ir of I-region gene products, in a fashion similar to the M0, where it was then recognized by helper T cells. Such an explanation was supported by the observation that high concentrations of antigen were required to elicit bystander help. This hypothesis raises the possibility of B cell processing of antigen bound to its immunoglobulin receptor and subsequent presentation of antigen to helper T cells.


Blood ◽  
1992 ◽  
Vol 79 (5) ◽  
pp. 1245-1254 ◽  
Author(s):  
N Chirmule ◽  
N Oyaizu ◽  
VS Kalyanaraman ◽  
S Pahwa

Abstract Despite the occurrence of hypergammaglobulinemia in human immunodeficiency virus (HIV) infection, specific antibody production and in vitro B-cell differentiation responses are frequently impaired. In this study, we have examined the effects of HIV envelope glycoprotein gp120 on T-helper cell function for B cells. In the culture system used, B-cell functional responses were dependent on T-B- cell contact, since separation of T and B cells in double chambers by Transwell membranes rendered the B cells unresponsive in assays of antigen-induced B-cell proliferation and differentiation. Cytokines secreted by T cells were also essential, since anti-CD3 monoclonal antibody (mAb)-activated, paraformaldehyde-fixed T-cell clones failed to induce B-cell proliferation and differentiation. Pretreatment of the CD4+ antigen-specific T cells with gp120 was found to impair their ability to help autologous B cells, as determined by B-cell proliferation, polyclonal IgG secretion, and antigen-specific IgG secretion. The gp120-induced inhibition was specific in that it was blocked by soluble CD4. Furthermore, only fractionated small B cells (which are T-cell-dependent in their function) manifested impaired responses when cultured with gp120-treated T cells. Antigen-induced interleukin (IL)-2 and IL-4, but not IL-6, secretion were markedly reduced in gp120-treated T-cell clones. Addition of exogenous cytokines failed to compensate for defective helper function of gp120-treated T cells. The findings in this study indicate that gp120 impairs helper functions of CD4+ T cells by interfering with T-B-cell contact- dependent interaction; the inhibitory effects of soluble envelope proteins of HIV may contribute to the immunopathogenesis of the HIV- associated disease manifestations.


Blood ◽  
2006 ◽  
Vol 107 (10) ◽  
pp. 3925-3932 ◽  
Author(s):  
Dong-Mei Zhao ◽  
Angela M. Thornton ◽  
Richard J. DiPaolo ◽  
Ethan M. Shevach

The suppressive capacity of naturally occurring mouse CD4+CD25+ T cells on T-cell activation has been well documented. The present study is focused on the interaction of CD4+CD25+ T cells and B cells. By coculturing preactivated CD4+CD25+ T cells with B cells in the presence of polyclonal B-cell activators, we found that B-cell proliferation was significantly suppressed. The suppression of B-cell proliferation was due to increased cell death caused by the CD4+CD25+ T cells in a cell-contact–dependent manner. The induction of B-cell death is not mediated by Fas–Fas ligand pathway, but surprisingly, depends on the up-regulation of perforin and granzymes in the CD4+CD25+ T cells. Furthermore, activated CD4+CD25+ T cells preferentially killed antigen-presenting but not bystander B cells. Our results demonstrate that CD4+CD25+ T cells can act directly on B cells and suggest that the prevention of autoimmunity by CD4+CD25+ T cells can be explained, at least in part, by the direct regulation of B-cell function.


Blood ◽  
1999 ◽  
Vol 94 (8) ◽  
pp. 2923-2930 ◽  
Author(s):  
Elie Haddad ◽  
Françoise Le Deist ◽  
Pierre Aucouturier ◽  
Marina Cavazzana-Calvo ◽  
Stephane Blanche ◽  
...  

We retrospectively analyzed the B-cell function and leukocyte chimerism of 22 patients with severe combined immunodeficiency with B cells (B+ SCID) who survived more than 2 years after bone marrow transplantation (BMT) to determine the possible consequences of BMT procedures, leukocyte chimerism, and SCID molecular deficit on B-cell function outcome. Circulating T cells were of donor origin in all patients. In recipients of HLA-identical BMT (n = 5), monocytes were of host origin in 5 and B cells were of host origin in 4 and of mixed origin in 1. In recipients of HLA haploidentical T-cell–depleted BMT (n = 17), B cells and monocytes were of host origin in 14 and of donor origin in 3. Engraftment of B cells was found to be associated with normal B-cell function. In contrast, 10 of 18 patients with host B cells still require Ig substitution. Conditioning regimen (ie, 8 mg/kg busulfan and 200 mg/kg cyclophosphamide) was shown neither to promote B-cell and monocyte engraftment nor to affect B-cell function. Eight patients with B cells of host origin had normal B-cell function. Evidence for functional host B cells was further provided in 3 informative cases by Ig allotype determination and by the detection, in 5 studied cases, of host CD27+ memory B cells as in age-matched controls. These results strongly suggest that, in some transplanted patients, host B cells can cooperate with donor T cells to fully mature in Ig-producing cells.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3078-3078
Author(s):  
Diane L Rossi ◽  
Edmund A Rossi ◽  
David M Goldenberg ◽  
Chien-Hsing Chang

Abstract Background Various formats of bispecific antibodies (bsAbs) to redirect effector T cells for the targeted killing of tumor cells have shown considerable promise both pre-clinically and clinically. The scFv-based constructs, including BiTE and DART, which bind monovalently to CD3 on T cells and to the target antigen on tumor cells, exhibit fast blood clearance and neurological toxicity due to their small size (∼55 kDa). Herein, we describe the generation of novel T-cell redirecting trivalent bsAbs comprising an anti-CD3 scFv covalently conjugated to a stabilized F(ab)2. The design was initially characterized with a prototype construct designated (19)-3s, which specifically targets CD19 on B cells. A panel of trivalent bsAbs was evaluated for their potential use in targeted T-cell immunotherapy of various B-cell malignancies. Potential advantages of this design include bivalent binding to tumor cells, a larger size (∼130 kDa) to preclude rapid renal clearance and penetration of the blood-brain barrier, and potent T-cell mediated cytotoxicity. Methods The DOCK-AND-LOCKTM (DNLTM) method was used to generate a panel of B-cell targeting bsAbs, (19)-3s, (20)-3s, (22)-3s, and (C2)-3s, which target CD19, CD20, CD22, and HLA-DR, respectively. This was achieved by combining a stabilized anti-X F(ab)2 with an anti-CD3-scFv, resulting in a homogeneous covalent structure of the designed composition, as shown by LC-MS, SE-HPLC, ELISA, SDS-PAGE, and immunoblot analyses. Each construct can mediate the formation of immunological synapses between T cells and malignant B cells, resulting in T-cell activation. At an E:T ratio of 10:1, using isolated T cells as effector cells, the bsAbs induced potent T-cell-mediated cytotoxicity in various B-cell malignancies, including Burkitt lymphomas (Daudi, Ramos, Namalwa), mantle cell lymphoma (Jeko-1), and acute lymphoblastic leukemia (Nalm-6). A non-tumor binding control, (14)-3s, induced only moderate T-cell killing at >10 nM. The nature of the antigen/epitope, particularly its size and proximity to the cell surface, appears to be more important than antigen density for T-cell retargeting potency (Table 1). It is likely that (20)-3s is consistently more potent than (19)-3s and (C2)-3s, even when the expression of CD19 or HLA-DR is considerably higher than CD20, as seen with Namalwa and Jeko-1, respectively. This is likely because the CD20 epitope comprises a small extracellular loop having close proximity to the cell surface. When compared directly using Daudi, (22)-3s was the least potent. Compared to CD19 and CD20, CD22 is expressed at the lowest density, is a rapidly internalizing antigen, and its epitope is further away from the cell surface; each of these factors may contribute to its reduced potency. Finally, sensitivity to T-cell retargeted killing is cell-line-dependent, as observed using (19)-3s, where Raji (IC50 >3 nM) is largely unresponsive yet Ramos (IC50 = 2 pM) is highly sensitive, even though the former expresses higher CD19 antigen density. Conclusions (19)-3s, (20)-3s, (22)-3s, and (C2)-3s can bind T cells and target B cells simultaneously and induce T-cell-mediated killing in vitro. The modular nature of the DNL method allowed the rapid production of several related conjugates for redirected T-cell killing of various B-cell malignancies, without the need for additional recombinant engineering and protein production. The close proximity of the CD20 extracellular epitope to the cell surface results in the highest potency for (20)-3s, which is an attractive candidate bsAb for use in this platform. We are currently evaluating the in vivo activity of these constructs to determine if this novel bsAb format offers additional advantages. Disclosures: Rossi: Immunomedics, Inc.: Employment. Rossi:Immunomedics, Inc.: Employment. Goldenberg:Immunomedics: Employment, stock options, stock options Patents & Royalties. Chang:Immunomedics, Inc: Employment, Stock option Other; IBC Pharmaceuticals, Inc.: Employment, Stock option, Stock option Other.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 295-295
Author(s):  
Teresa Sadras ◽  
Mickaël Martin ◽  
Lauren Kim-Sing ◽  
Jevon Cutler ◽  
Gal Lenz ◽  
...  

B-cells are under intense selective pressure to eliminate autoreactive or premalignant clones. B-cell receptor (BCR) signals are required for survival, however, BCR-signaling exceeding maximum thresholds often reflects signaling from an autoreactive BCR or a transforming oncogene and triggers negative selection and cell death. The tyrosine kinase SYK initiates BCR-downstream signaling in B-cells while its close relative ZAP70 is almost exclusively expressed in T-cells. Interestingly, the segregation of SYK to B-cells and ZAP70 to T-cells is less confined in malignant lymphopoiesis suggesting that the balance of these related kinases may alter signaling output in disease and contribute to development of leukemia. As previously shown in B-cell chronic lymphocytic leukemia (B-CLL), we identified aberrant ZAP70 expression as a frequent feature in multiple other B-cell malignancies that depend on survival signals from a functional (pre-) BCR (E2A-PBX1+ pre-B ALL, and mantle cell lymphoma) or harbor oncogenic mimics of the BCR (BCR-ABL1+ B-ALL). Studying SYK and ZAP70 expression by single-cell Western blot, co-expression of the two tyrosine kinases was extremely rare in normal B- and T-cell populations. In contrast, &gt;50% of tumor B-cells in mantle cell lymphoma, pre-B ALL and CLL co-expressed SYK and ZAP70. Despite their structural similarities, genetic deletion and engineered reconstitution of SYK and ZAP70 in human B-cell lymphoma cells revealed striking functional differences. Proximity-dependent biotin identification (BioID) analyses identified that SYK, but not ZAP70, engaged the PI3K pathway via interaction with CD19. Consistent with this, reconstitution with SYK and SYK-ZAP70 but not ZAP70 alone promoted survival and proliferation. Detailed analysis of BCR-mediated cascades in lymphoma cells expressing SYK, ZAP70 or SYK-ZAP70 established that ZAP70 is only weakly efficient at propagating BCR-mediated calcium and downstream pathway activation in B-cells. Strikingly, co-expression of ZAP70 with SYK resulted in re-wired BCR-signaling of intermediate strength: compared to cells expressing only SYK, SYK-ZAP70 co-expressing cells had markedly reduced activation of the BLNK-BTK-PLCγ pathway, further reflected in BCR-induced Ca2+ signaling with delayed onset, lower amplitude but longer duration. In this way, we speculated that SYK and ZAP70 may be present within close proximity at the apex of BCR-initiated interactions, and hence compete for downstream substrates resulting in a re-wiring of classic signaling programs propagated normally by SYK. To explore this, we utilized proximity ligation assays (PLA) to monitor the proximity of SYK and ZAP70 in resting or BCR-stimulated B-cells, and found that SYK and ZAP70 co-exist within close proximity consistent with the view that varying levels of these kinases may alter B-cell signaling output. Functional experiments further showed that phosphomimetic activation of SYK, but not ZAP70, induced hyperactivation of PI3K-signaling and acute BTK-mediated cell death in pre-B ALL cells. In line with altered BCR-signaling strength and quality in SYK and ZAP70 co-expressing cells, over-expression of Zap70 in pre-B ALL cells rescued auto-immune checkpoint activation induced by hyper-activation of BCR-associated signaling. To study functional consequences of SYK-ZAP70 co-expression during normal B-cell development, we generated a novel knock in Zap-70+/Mb1-Cre+mouse model, to induce conditional expression of Zap70 in the B cell compartment from the proB stage. Consistent with compromised central tolerance checkpoints, Syk-Zap70 co-expressing pro/pre-B and immature B-cells had reduced spontaneous apoptosis rates and gave rise to autoantibody production against multiple self-antigens. Importantly, our findings highlight a previously unrecognized role for ZAP70 in oncogenic BCR-signaling and we conclude that the co-expression of ZAP70 mitigates the ability of SYK, downstream of an autoreactive BCR or a transforming oncogene, to trigger negative B-cell selection and cell death (Figure 1). Disclosures Weinstock: Celgene: Research Funding. Meffre:AbbVie: Consultancy, Other: Grant.


2021 ◽  
Vol 12 ◽  
Author(s):  
Claire Germain ◽  
Priyanka Devi-Marulkar ◽  
Samantha Knockaert ◽  
Jérôme Biton ◽  
Hélène Kaplon ◽  
...  

The presence of tertiary lymphoid structures (TLS) in the tumor microenvironment is associated with better clinical outcome in many cancers. In non-small cell lung cancer (NSCLC), we have previously showed that a high density of B cells within TLS (TLS-B cells) is positively correlated with tumor antigen-specific antibody responses and increased intratumor CD4+ T cell clonality. Here, we investigated the relationship between the presence of TLS-B cells and CD4+ T cell profile in NSCLC patients. The expression of immune-related genes and proteins on B cells and CD4+ T cells was analyzed according to their relationship to TLS-B density in a prospective cohort of 56 NSCLC patients. We observed that tumor-infiltrating T cells showed marked differences according to TLS-B cell presence, with higher percentages of naïve, central-memory, and activated CD4+ T cells and lower percentages of both immune checkpoint (ICP)-expressing CD4+ T cells and regulatory T cells (Tregs) in the TLS-Bhigh tumors. A retrospective study of 538 untreated NSCLC patients showed that high TLS-B cell density was even able to counterbalance the deleterious impact of high Treg density on patient survival, and that TLS-Bhigh Treglow patients had the best clinical outcomes. Overall, the correlation between the density of TLS-Bhigh tumors with early differentiated, activated and non-regulatory CD4+ T cell cells suggest that B cells may play a central role in determining protective T cell responses in NSCLC patients.


Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2085-2085
Author(s):  
Rao H Prabhala ◽  
Srikanth Talluri ◽  
Megan Stekla ◽  
Andreea Negroiu ◽  
Michael Buonopane ◽  
...  

Abstract One of the most prominent features of multiple myeloma (MM) has been immune deficiency which predisposes patients to infectious complications and suppresses development of anti-MM immune responses. We and others have previously described the T cell dysfunction in Th1, Treg and Th17 cells, plasmacytoid dendritic cells and myeloid-derived suppressor cells (MDSC). However, the most fundamental and long identified deficiency is in the humoral immune response. Suppression of uninvolved immunoglobulins (UIgs) have been well described (i.e. suppression of serum IgA and IgM in IgG myeloma); and antibody responses to vaccination have been inadequate. However, very limited information is available regarding B cell function and how UIgs are suppressed in myeloma. We have now evaluated six different B cell subsets (B1a, B1b, B2, Breg, IRA-B, and MZ) in peripheral blood (PBMC) and bone marrow (BM) to understand alterations in B cell immune function in MM. We have observed significantly lower ratio of B2 (normal B cell-subset) and B1a (natural antibody-producing cells) subsets (10±4 vs 57±17; p < 0.05) and B2 and Breg (regulatory B cell-subset) subsets (14±4 vs 45±13; p< 0.05) in PBMC from MM patients (N=19) compared with healthy donor (N=33) respectively. Similar results were observed in BM samples from MM patients (N=18) compared with healthy donors (N=12); B2/B1a subset (2.4±0.6 vs 8±1.3; p < 0.05) and B2/Breg subset (8±1.4 vs 43.7±8.4; p< 0.05) respectively. To understand whether MM cells directly or indirectly alter B cell-subsets, we incubated myeloma cells (N=4) with healthy donor PBMCs, and analyzed B cell subsets after 3 days. We observed significant elevation in B1 subset (2.5 fold of control) and reduced B2 subset (89±3% of control). When we incubated PBMCs with IL-17A over-expressing MM cells (N=3), we observed further significant reduction in B2 subset (74% of control). When normal PBMCs are cultured in IL-17A (N=4) we observed significantly increased IL-10-producing Breg subset (28% of control). Similarly, co-culture of healthy B cells with MDSC led to significant increase (3.8 times) in Breg cell- population (N=3) compared with control group. To study the impact of B cell dysfunction on T cell function in MM, we activated normal PBMC via anti-CD3 antibody, in the presence or absence of B cells, and measured intra-cellular IFN-γ levels in CD69+ cells. We observed that the absence of B cells significantly inhibited interferon-producing T cells compared to control (by 43%; p<0.05). Importantly, following removal of CD25+ cells (Tregs and activated memory T cells), with or without B cells, we did not observe any difference in the inhibition of IFN-γ, indicating that B cells influence memory T cells rather than naïve T cells for the production of IFN-γ. To evaluate impact of lenalidomide on this interaction, we stimulated purified normal donor CD45RO memory T cells with Th1 polarizing cocktail in the presence or absence of purified normal B cells or B cells from MM patient (MM-B) in presence of lenalidomide and observed thatlenalidomide significantly improved MM-B cell-mediated IFN-γ-producing Th1 responses (by 32%, p<0.05) compared to normal B cell-mediated Th1 responses. In an effort to evaluate whether any therapy may improve the B cell function, we cultured normal PBMCs in the presence of lenalidomide (N=9) and observed reduction in Breg subset by 40% of control. To evaluate the effect of therapy on B cell-subsets in MM, we analyzed B cell subsets in PBMC from newly-diagnosed and lenalidomide-treated MM patients and observed that lenalidomide-treated group showed significant (p<0.05) improvement in B cell subsets (increased B2 and lower B1 cells) even before clinical response. These results suggest that immunomodulatory agents may be able to re-program humoral immunity in these patients. In summary, we report that the myeloma cell driven skewed B cell subset distribution with consequent B cell dysfunction drives the observed abnormalities in humoral/cell mediated immunity. The current therapeutic interventions, besides providing deep clinical responses, may also improve B cell function with impact on long term outcome. Disclosures No relevant conflicts of interest to declare.


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