Sex Differences in the Immune System Become Evident in the Perinatal Period in the Four Core Genotypes Mouse

We have used the four core genotypes (FCG) mouse model, which allows a distinction between effects of gonadal secretions and chromosomal complement, to determine when sex differences in the immune system first appear and what influences their development. Using splenic T cell number as a measure that could be applied to neonates with as yet immature immune responses, we found no differences among the four genotypes at postnatal day 1, but by day 7, clear sex differences were observed. These sex differences were unexpectedly independent of chromosomal complement and similar in degree to gonadectomized FCG adults: both neonatal and gonadectomized adult females (XX and XY) showed 2-fold the number of CD4+ and 7-fold the number of CD8+ T cells versus their male (XX and XY) counterparts. Appearance of this long-lived sex difference between days 1 and 7 suggested a role for the male-specific perinatal surge of testicular testosterone. Interference with the testosterone surge significantly de-masculinized the male CD4+, but not CD8+ splenic profile. Treatment of neonates demonstrated elevated testosterone limited mature cell egress from the thymus, whereas estradiol reduced splenic T cell seeding in females. Neonatal male splenic epithelium/stroma expressed aromatase mRNA, suggesting capacity for splenic conversion of perinatal testosterone into estradiol in males, which, similar to administration of estradiol in females, would result in reduced splenic T cell seeding. These sex steroid effects affected both CD4+ and CD8+ cells and yet interference with the testosterone surge only significantly de-masculinized the splenic content of CD4+ cells. For CD8+ cells, male cells in the thymus were also found to express one third the density of sphingosine-1-phosphate thymic egress receptors per cell compared to female, a male characteristic most likely an indirect result of Sry expression. Interestingly, the data also support a previously unrecognized role for non-gonadal estradiol in the promotion of intra-thymic cell proliferation in neonates of both sexes. Microarray analysis suggested the thymic epithelium/stroma as the source of this hormone. We conclude that some immune sex differences appear long before puberty and more than one mechanism contributes to differential numbers and distribution of T cells.

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Immune Dysfunction in Patients with MDS Is Partially Corrected in EPO-Treated Patients: Differences According to WHO Classification

Blood ◽

10.1182/blood.v128.22.3165.3165 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3165-3165

Author(s):

Howard S Oster ◽

Naamit Deshet-Unger ◽

Drorit Neumann ◽

Moshe Mittelman ◽

Nir Maaravi ◽

...

Keyword(s):

T Cells ◽

Immune System ◽

T Cell ◽

Cd8 T Cells ◽

Healthy Subjects ◽

Advanced Disease ◽

Fold Increase ◽

Refractory Anemia ◽

Cd8 Cells ◽

Cell Numbers

Abstract Background: The immune system has been shown to be involved in the pathogenesis of myelodysplastic syndromes (MDS), and is also affected by the disease. Recombinant erythropoietin (rHuEPO), or in general, erythroid stimulating agents (ESAs) have become a standard treatment for anemic patients with MDS. They were found to improve anemia, quality of life, and possibly survival. We have previously demonstrated that EPO has effects on cellular and humoral immunity and specifically, on immune function in patients with multiple myeloma (MM). Here we report our findings demonstrating the effect of ESAs on T cell (CD4+, CD8+ and CD4+CD25+) number and function in patients with MDS. Patients and Methods: We examined three groups: healthy subjects ('Control', 20 participants), MDS patients without ESA treatment ('MDS', 13), and MDS patients treated with an ESA ('MDS+EPO', 17). All diagnosed patients gave informed consent as approved by our IRB. Cell numbers were evaluated with flow cytometry. In a subset of patients, cell activation was assessed in response to phytohemagglutinin (PHA) by examining CD69 expression in both CD4+ and CD8+ cells. The co-stimulatory marker, CD28, and the inhibitory marker CTLA-4 (CD152) were evaluated as well. We also examined World Health Organization (WHO) subgroups, refractory anemia (RA) and RA with ringed sideroblasts (RARS) versus more advanced disease. Results: CD4+ and CD8+ T cell levels are reduced and increased respectively in MDS patients compared to control, and these changes are reversed in MDS+EPO (Table 1, CD4+, p<0.01; CD8+, p=0.05). The CD4+:CD8+ ratio (Table 1) is reduced and nearly equalized in MDS (1.16), but approaches that of the control (2.24) in MDS+EPO (1.94). CD4+CD25+ T cell numbers (including regulatory T cells), were lower in MDS patients and improve in the MDS+EPO group (Table 1). In vitro activation of T cells (CD4+CD69+ and CD8+CD69+) achieves an approximately 15-fold increase in healthy subjects. MDS patients without EPO sustained only a 7.17 fold increase in CD4+ activation versus 13.64 fold for the MDS+EPO group (p<0.01); for CD8+ T cells, 10.20 fold (MDS) versus 18.56 fold (MDS+EPO, p<0.01). The expression of the co-stimulatory marker CD28 was decreased in both CD4+ and CD8+ T cells in MDS, and approached normal in MDS+EPO in CD4+ T cells (Table 1). There was no significant change in inhibitory CTLA-4 (CD152) expression among the groups (not shown). Subgroup analysis demonstrated that ESA has a similar effect on CD4+ and CD8+ cells and their ratio in both RA/RARS and more advanced disease, similar to those of the whole cohort (Table 2, green). On the other hand, some parameters were affected by ESA only in one subgroup (Table 2, blue): The ESA effect on CD4+CD25+ cells was evident only in patients with advanced disease (Table 2, blue). ESA affected CD4+ and CD8+ cell stimulation (CD69) in RA/RARS, similar to that seen in the whole cohort (Table 2, blue). Of note, in more advanced disease, CD4+ and CD8+ cells achieved stimulation in the MDS group not treated with ESA, with no difference between MDS and MDS+EPO. This finding needs to be further addressed in larger cohorts and with additional markers of activation. Conclusions: MDS patients display T-cell abnormalities that are improved upon EPO treatment. MDS is a heterogeneous disease where the immune system both affects and is affected by the disease. As such, treatment with ESAs might ameliorate not only the anemia, but also the immune deficiencies and perhaps the disease itself. Future studies will clarify the immunomodulatory role of ESA in the various stages of MDS. Disclosures No relevant conflicts of interest to declare.

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Synthetic mycobacterial diacyl trehaloses reveal differential recognition by human T cell receptors and the C-type lectin Mincle

Scientific Reports ◽

10.1038/s41598-021-81474-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Josephine F. Reijneveld ◽

Mira Holzheimer ◽

David C. Young ◽

Kattya Lopez ◽

Sara Suliman ◽

...

Keyword(s):

T Cells ◽

Fatty Acid ◽

Immune System ◽

T Cell ◽

Cross Reactivity ◽

Lipid Binding ◽

Human Immune System ◽

Human T Cell ◽

Human T Cells ◽

Pure Compounds

AbstractThe cell wall of Mycobacterium tuberculosis is composed of diverse glycolipids which potentially interact with the human immune system. To overcome difficulties in obtaining pure compounds from bacterial extracts, we recently synthesized three forms of mycobacterial diacyltrehalose (DAT) that differ in their fatty acid composition, DAT1, DAT2, and DAT3. To study the potential recognition of DATs by human T cells, we treated the lipid-binding antigen presenting molecule CD1b with synthetic DATs and looked for T cells that bound the complex. DAT1- and DAT2-treated CD1b tetramers were recognized by T cells, but DAT3-treated CD1b tetramers were not. A T cell line derived using CD1b-DAT2 tetramers showed that there is no cross-reactivity between DATs in an IFN-γ release assay, suggesting that the chemical structure of the fatty acid at the 3-position determines recognition by T cells. In contrast with the lack of recognition of DAT3 by human T cells, DAT3, but not DAT1 or DAT2, activates Mincle. Thus, we show that the mycobacterial lipid DAT can be both an antigen for T cells and an agonist for the innate Mincle receptor, and that small chemical differences determine recognition by different parts of the immune system.

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Interleukins and Interleukin Receptors Evolutionary History and Origin in Relation to CD4+ T Cell Evolution

Genes ◽

10.3390/genes12060813 ◽

2021 ◽

Vol 12 (6) ◽

pp. 813

Author(s):

Norwin Kubick ◽

Pavel Klimovich ◽

Patrick Henckell Flournoy ◽

Irmina Bieńkowska ◽

Marzena Łazarczyk ◽

...

Keyword(s):

T Cells ◽

Immune System ◽

T Cell ◽

Positive Selection ◽

Cd4 T Cells ◽

Cell Function ◽

Single Gene ◽

Ancestral Reconstruction ◽

Critical Function ◽

Interleukin Receptors

Understanding the evolution of interleukins and interleukin receptors is essential to control the function of CD4+ T cells in various pathologies. Numerous aspects of CD4+ T cells’ presence are controlled by interleukins including differentiation, proliferation, and plasticity. CD4+ T cells have emerged during the divergence of jawed vertebrates. However, little is known about the evolution of interleukins and their origin. We traced the evolution of interleukins and their receptors from Placozoa to primates. We performed phylogenetic analysis, ancestral reconstruction, HH search, and positive selection analysis. Our results indicated that various interleukins' emergence predated CD4+ T cells divergence. IL14 was the most ancient interleukin with homologs in fungi. Invertebrates also expressed various interleukins such as IL41 and IL16. Several interleukin receptors also appeared before CD4+ T cells divergence. Interestingly IL17RA and IL17RD, which are known to play a fundamental role in Th17 CD4+ T cells first appeared in mollusks. Furthermore, our investigations showed that there is not any single gene family that could be the parent group of interleukins. We postulate that several groups have diverged from older existing cytokines such as IL4 from TGFβ, IL10 from IFN, and IL28 from BCAM. Interleukin receptors were less divergent than interleukins. We found that IL1R, IL7R might have diverged from a common invertebrate protein that contained TIR domains, conversely, IL2R, IL4R and IL6R might have emerged from a common invertebrate ancestor that possessed a fibronectin domain. IL8R seems to be a GPCR that belongs to the rhodopsin-like family and it has diverged from the Somatostatin group. Interestingly, several interleukins that are known to perform a critical function for CD4+ T cells such as IL6, IL17, and IL1B have gained new functions and evolved under positive selection. Overall evolution of interleukin receptors was not under significant positive selection. Interestingly, eight interleukin families appeared in lampreys, however, only two of them (IL17B, IL17E) evolved under positive selection. This observation indicates that although lampreys have a unique adaptive immune system that lacks CD4+ T cells, they could be utilizing interleukins in homologous mode to that of the vertebrates' immune system. Overall our study highlights the evolutionary heterogeneity within the interleukins and their receptor superfamilies and thus does not support the theory that interleukins evolved solely in jawed vertebrates to support T cell function. Conversely, some of the members are likely to play conserved functions in the innate immune system.

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Neonatal lymphocyte subpopulations analysis and maternal preterm premature rupture of membranes: a pilot study

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2021-0375 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Margherita Amadi ◽

Silvia Visentin ◽

Francesca Tosato ◽

Paola Fogar ◽

Giulia Giacomini ◽

...

Keyword(s):

T Cells ◽

Immune System ◽

T Cell ◽

T Helper Cells ◽

Lymphocyte Subpopulations ◽

T Helper ◽

Premature Rupture Of Membranes ◽

Premature Rupture ◽

Preterm Premature Rupture ◽

Helper Cells

Abstract Objectives Preterm premature rupture of membranes (pPROM) causes preterm delivery, and increases maternal T-cell response against the fetus. Fetal inflammatory response prompts maturation of the newborn’s immunocompetent cells, and could be associated with unfavorable neonatal outcome. The aims were to examine the effects of pPROM (Mercer BM. Preterm premature rupture of the membranes: current approaches to evaluation and management. Obstet Gynecol Clin N Am 2005;32:411) on the newborn’s and mother’s immune system and (Test G, Levy A, Wiznitzer A, Mazor M, Holcberg G, Zlotnik A, et al. Factors affecting the latency period in patients with preterm premature rupture of membranes (pPROM). Arch Gynecol Obstet 2011;283:707–10) to assess the predictive value of immune system changes in neonatal morbidity. Methods Mother-newborn pairs (18 mothers and 23 newborns) who experienced pPROM and controls (11 mothers and 14 newborns), were enrolled. Maternal and neonatal whole blood samples underwent flow cytometry to measure lymphocyte subpopulations. Results pPROM-newborns had fewer naïve CD4 T-cells, and more memory CD4 T-cells than control newborns. The effect was the same for increasing pPROM latency times before delivery. Gestational age and birth weight influenced maturation of the newborns’ lymphocyte subpopulations and white blood cells, notably cytotoxic T-cells, regulatory T-cells, T-helper cells (absolute count), and CD4/CD8 ratio. Among morbidities, fewer naïve CD8 T-cells were found in bronchopulmonary dysplasia (BPD) (p=0.0009), and more T-helper cells in early onset sepsis (p=0.04). Conclusions pPROM prompts maturation of the newborn’s T-cell immune system secondary to antigenic stimulation, which correlates with pPROM latency. Maternal immunity to inflammatory conditions is associated with a decrease in non-major histocompatibility complex (MHC)-restricted cytotoxic cells.

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721 AT1412, a patient-derived CD9 antibody in preclinical development promoting tumor immune infiltration and inducing tumor rejection

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0721 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A763-A763

Author(s):

Remko Schotte ◽

Julien Villaudy ◽

Martijn Kedde ◽

Wouter Pos ◽

Daniel Go ◽

...

Keyword(s):

T Cells ◽

Immune System ◽

T Cell ◽

Tumor Cells ◽

Tumor Rejection ◽

Human Immune System ◽

Preclinical Development ◽

High Affinity ◽

Human Immune ◽

A375 Melanoma

BackgroundAdaptive immunity to cancer cells forms a crucial part of cancer immunotherapy. Recently, the importance of tumor B-cell signatures were shown to correlate with melanoma survival. We investigated whether tumor-targeting antibodies could be isolated from a patient that cured (now 13 years tumor-free) metastatic melanoma following adoptive transfer of ex vivo expanded autologous T cells.MethodsPatient‘s peripheral blood B cells were isolated and tested for the presence of tumor-reactive B cells using AIMM’s immmortalisation technology. Antibody AT1412 was identified by virtue of its differential binding to melanoma cells as compared to healthy melanocytes. AT1412 binds the tetraspanin CD9, a broadly expressed protein involved in multiple cellular activities in cancer and induces ADCC and ADCP by effector cells.ResultsSpontaneous immune rejection of tumors was observed in human immune system (HIS) mouse models implanted with CD9 genetically-disrupted A375 melanoma (A375-CD9KO) tumor cells, while A375wt cells were not cleared. Most notably, no tumor rejection of A375-CD9KO tumors was observed in NSG mice, indicating that blockade of CD9 makes tumor cells susceptible to immune rejection.CD9 has been described to regulate integrin signaling, e.g. LFA-1, VLA-4, VCAM-1 and ICAM-1. AT1412 was shown to modulate CD9 function by enhancing adhesion and transmigration of T cells to endothelial (HUVEC) cells. AT1412 was most potently enhancing transendothelial T-cell migration, in contrast to a high affinity version of AT1412 or other high affinity anti-CD9 reference antibodies (e.g. ALB6). Enhanced immune cell infiltration is also observed in immunodeficient mice harbouring a human immune system (HIS). AT1412 strongly enhanced CD8 T-cell and macrophage infiltration resulting in tumor rejection (A375 melanoma). PD-1 checkpoint blockade is further sustaining this effect. In a second melanoma model carrying a PD-1 resistant and highly aggressive tumor (SK-MEL5) AT1412 together with nivolumab was inducing full tumor rejection, while either one of the antibodies alone did not.ConclusionsThe safety of AT1412 has been assessed in preclinical development and is well tolerated up to 10 mg/kg (highest dose tested) by non human primates. AT1412 demonstrated a half-life of 8.5 days, supporting 2–3 weekly administration in humans. Besides transient thrombocytopenia no other pathological deviations were observed. No effect on coagulation parameters, bruising or bleeding were observed macro- or microscopically. The thrombocytopenia is reversible, and its recovery accelerated in those animals developing anti-drug antibodies. First in Human clinical study is planned to start early 2021.Ethics ApprovalStudy protocols were approved by the Medical Ethical Committee of the Leiden University Medical Center (Leiden, Netherlands).ConsentBlood was obtained after written informed consent by the patient.

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CD28 Costimulation Is Required for In Vivo Induction of Peripheral Tolerance in CD8 T Cells

Journal of Experimental Medicine ◽

10.1084/jem.20021429 ◽

2002 ◽

Vol 197 (1) ◽

pp. 19-26 ◽

Cited By ~ 27

Author(s):

Melanie S. Vacchio ◽

Richard J. Hodes

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Tolerance Induction ◽

Peripheral Tolerance ◽

Cd8 Cells ◽

Costimulatory Signal ◽

Cd28 Costimulation

Whereas ligation of CD28 is known to provide a critical costimulatory signal for activation of CD4 T cells, the requirement for CD28 as a costimulatory signal during activation of CD8 cells is less well defined. Even less is known about the involvement of CD28 signals during peripheral tolerance induction in CD8 T cells. In this study, comparison of T cell responses from CD28-deficient and CD28 wild-type H-Y–specific T cell receptor transgenic mice reveals that CD8 cells can proliferate, secrete cytokines, and generate cytotoxic T lymphocytes efficiently in the absence of CD28 costimulation in vitro. Surprisingly, using pregnancy as a model to study the H-Y–specific response of maternal T cells in the presence or absence of CD28 costimulation in vivo, it was found that peripheral tolerance does not occur in CD28KO pregnants in contrast to the partial clonal deletion and hyporesponsiveness of remaining T cells observed in CD28WT pregnants. These data demonstrate for the first time that CD28 is critical for tolerance induction of CD8 T cells, contrasting markedly with CD28 independence of in vitro activation, and suggest that the role of CD28/B7 interactions in peripheral tolerance of CD8 T cells may differ significantly from that of CD4 T cells.

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Keratinocyte growth factor enhances DNA plasmid tumor vaccine responses after murine allogeneic bone marrow transplantation

Blood ◽

10.1182/blood-2008-05-155697 ◽

2009 ◽

Vol 113 (7) ◽

pp. 1574-1580 ◽

Cited By ~ 20

Author(s):

Robert R. Jenq ◽

Christopher G. King ◽

Christine Volk ◽

David Suh ◽

Odette M. Smith ◽

...

Keyword(s):

Bone Marrow ◽

T Cells ◽

T Cell ◽

Keratinocyte Growth Factor ◽

Allogeneic Bone Marrow Transplantation ◽

Allogeneic Bone ◽

Effector Cells ◽

Cd8 Cells ◽

T Cell Reconstitution ◽

Dna Plasmid

Abstract Keratinocyte growth factor (KGF), which is given exogenously to allogeneic bone marrow transplantation (allo-BMT) recipients, supports thymic epithelial cells and increases thymic output of naive T cells. Here, we demonstrate that this improved T-cell reconstitution leads to enhanced responses to DNA plasmid tumor vaccination. Tumor-bearing mice treated with KGF and DNA vaccination have improved long-term survival and decreased tumor burden after allo-BMT. When assayed before vaccination, KGF-treated allo-BMT recipients have increased numbers of peripheral T cells, including CD8+ T cells with vaccine-recognition potential. In response to vaccination, KGF-treated allo-BMT recipients, compared with control subjects, generate increased numbers of tumor-specific CD8+ cells, as well as increased numbers of CD8+ cells producing interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α). We also found unanticipated benefits to antitumor immunity with the administration of KGF. KGF-treated allo-BMT recipients have an improved ratio of T effector cells to regulatory T cells, a larger fraction of effector cells that display a central memory phenotype, and effector cells that are derived from a broader T-cell–receptor repertoire. In conclusion, our data suggest that KGF can function as a potent vaccine adjuvant after allo-BMT through its effects on posttransplantation T-cell reconstitution.

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Vigorous Premalignancy-specific Effector T Cell Response in the Bone Marrow of Patients with Monoclonal Gammopathy

Journal of Experimental Medicine ◽

10.1084/jem.20031030 ◽

2003 ◽

Vol 198 (11) ◽

pp. 1753-1757 ◽

Cited By ~ 131

Author(s):

Madhav V. Dhodapkar ◽

Joseph Krasovsky ◽

Keren Osman ◽

Matthew D. Geller

Keyword(s):

T Cells ◽

Immune System ◽

T Cell ◽

Cell Response ◽

Direct Evidence ◽

Human Cancer ◽

T Cell Response ◽

Immune Recognition ◽

Effector T Cell ◽

Specific Effector

Most approaches targeting the immune system against tumors have focused on patients with established tumors. However, whether the immune system can recognize preneoplastic stages of human cancer is not known. Here we show that patients with preneoplastic gammopathy mount a vigorous T cell response to autologous premalignant cells. This preneoplasia-specific CD4+ and CD8+ T cell response is detected in freshly isolated T cells from the BM. T cells from myeloma marrow lack this tumor-specific rapid effector function. These data provide direct evidence for tumor specific immune recognition in human preneoplasia and suggest a possible role for the immune system in influencing the early growth of transformed cells, long before the development of clinical cancer.

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The impact of body mass index on adaptive immune cells in the human bone marrow

10.21203/rs.2.22852/v2 ◽

2020 ◽

Author(s):

Luca Pangrazzi ◽

Erin Naismith ◽

Carina Miggitsch ◽

Jose’ Antonio Carmona Arana ◽

Michael Keller ◽

...

Keyword(s):

Body Mass Index ◽

Bone Marrow ◽

T Cells ◽

Immune System ◽

T Cell ◽

Immune Cells ◽

Memory T Cells ◽

T Cell Subsets ◽

Adaptive Immune ◽

Adaptive Immune Cells

Abstract Background. Obesity has been associated with chronic inflammation and oxidative stress. Both conditions play a determinant role in the pathogenesis of age-related diseases, such as immunosenescence. Adipose tissue can modulate the function of the immune system with the secretion of molecules influencing the phenotype of immune cells. The importance of the bone marrow (BM) in the maintenance of antigen-experienced adaptive immune cells has been documented in mice. Recently, some groups have investigated the survival of effector/memory T cells in the human BM. Despite this, whether high body mass index (BMI) may affect immune cells in the BM and the production of molecules supporting the maintenance of these cells it is unknown.Methods. Using flow cytometry, the frequency and the phenotype of immune cell populations were measured in paired BM and PB samples obtained from persons with different BMI. Furthermore, the expression of BM cytokines was assessed. The influence of cytomegalovirus (CMV) on T cell subsets was additionally considered, dividing the donors into the CMV- and CMV+ groups.Results. Our study suggests that increased BMI may affect both the maintenance and the phenotype of adaptive immune cells in the BM. While the BM levels of IL-15 and IL-6, supporting the survival of highly differentiated T cells, and oxygen radicals increased in overweight persons, the production of IFNγ and TNF by CD8+ T cells was reduced. In addition, the frequency of B cells and CD4+ T cells positively correlated with BMI in the BM of CMV- persons. Finally, the frequency of several T cell subsets, and the expression of senescence/exhaustion markers within these subpopulations, were affected by BMI. In particular, the levels of bona fide memory T cells may be reduced in overweight persons.Conclusion. Our work suggests that, in addition to aging and CMV, obesity may represent an additional risk factor for immunosenescence in adaptive immune cells. Metabolic interventions may help in improving the fitness of the immune system in the elderly.

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Prolonged activation of nasal immune cell populations and development of tissue-resident SARS-CoV-2 specific CD8 T cell responses following COVID-19

10.1101/2021.04.19.21255727 ◽

2021 ◽

Author(s):

Anna H.E. Roukens ◽

Marion König ◽

Tim Dalebout ◽

Tamar Tak ◽

Shohreh Azimi ◽

...

Keyword(s):

T Cells ◽

Immune System ◽

T Cell ◽

Nasal Mucosa ◽

Immune Cell ◽

Inflammatory Responses ◽

Upper Airway ◽

Effector Memory ◽

Long Term Effects ◽

Activated T Cells

AbstractThe immune system plays a major role in Coronavirus Disease 2019 (COVID-19) pathogenesis, viral clearance and protection against re-infection. Immune cell dynamics during COVID-19 have been extensively documented in peripheral blood, but remain elusive in the respiratory tract. We performed minimally-invasive nasal curettage and mass cytometry to characterize nasal immune cells of COVID-19 patients during and 5-6 weeks after hospitalization. Contrary to observations in blood, no general T cell depletion at the nasal mucosa could be detected. Instead, we observed increased numbers of nasal granulocytes, monocytes, CD11c+ NK cells and exhausted CD4+ T effector memory cells during acute COVID-19 compared to age-matched healthy controls. These pro-inflammatory responses were found associated with viral load, while neutrophils also negatively correlated with oxygen saturation levels. Cell numbers mostly normalized following convalescence, except for persisting CD127+ granulocytes and activated T cells, including CD38+ CD8+ tissue-resident memory T cells. Moreover, we identified SARS-CoV-2 specific CD8+ T cells in the nasal mucosa in convalescent patients. Thus, COVID-19 has both transient and long-term effects on the immune system in the upper airway.

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