Effect of Streptococcus uberis on Gamma Delta T Cell Phenotype in Bovine Mammary Gland

In this study, we focused analyzing γδ T cells during bovine mammary gland inflammation induced by Streptococcus uberis. A mammary gland cell suspension was obtained using lavage 24, 48, 72, and 168 h after intramammary-induced infection. The proportion of lymphocytes increased during the entire week in which inflammation was present. The γδ T cells were also elevated during inflammation, reaching their peak at 72 h following induced inflammation. The percentage of apoptotic lymphocytes continually increased, with the highest proportion occurring 168 h after S. uberis infection. The results show that γδ T cells may be involved in the resolution of inflammation in bovine mammary glands, with the apoptosis of those cells potentially playing an important role.

Primary Cutaneous Gamma-Delta T Cell Lymphomas: A Case Series and Overview of the Literature

Primary cutaneous gamma-delta T cell lymphomas (PCGDTCLs) are rare and aggressive cutaneous malignancies that have been diagnostically challenging for dermopathologists and clinicians since their first published descriptions in 1991. Since then, the availability of immunostaining for T cell receptors γ and δ in formalin-fixed paraffin-embedded samples has greatly increased our knowledge of the gamma-delta phenotype by showing that it may also be present in the context of indolent entities, such as mycosis fungoides (MFs) and lymphomatoid papulosis, and this has raised questions concerning its diagnostic and prognostic implications. We here describe the histological and clinical differences between the dermo-epidermal and subcutaneous sub-groups of PCGDTCL observed in a cohort of 20 patients attending a single experienced centre, with particular focus on cases with an MF-like presentation, which are still less well defined than those of classic MF.

EXTH-25. ENHANCING GLIOBLASTOMA CELL STRESS RESPONSE TO IMPROVE GAMMA DELTA T-CELL IMMUNOTHERAPY

Glioblastoma (GBM) is an aggressive cancer that has been largely intractable to novel therapies, however, enhancing the efficacy of immunotherapy could potentially overcome immunosuppression and potentially improve patient outcomes. The cellular stress induced by Temozolomide (TMZ) increases innate immune ligands, which could be exploited to promote immune recognition. TMZ-induced DNA damage can activate the stress response pathway, increasing the expression of NKG2D ligands (NKG2DL) on tumor cells. This leads to an increase in NKG2DL recognition by NKG2D receptors on both natural killer and cytotoxic T-cells to elicit a cytotoxic effect. The lymphodepleting effect of TMZ, however, can limit the ability of these cells to recognize and kill tumor cells. TMZ was shown to induce NKG2DL in gliomas both in vitro and in vivo, providing the basis for clinical trials of TMZ in combination with genetically engineered TMZ-resistant gamma delta T-cells (NCT04165941). To further promote immune recognition, we sought to augment the TMZ-induced stress response by exploring the combination of DNA alkylation with either PARP (Niraparib) or ATM Kinase inhibition (AZD1390). Combinatorial therapy significantly, but heterogeneously, increased differential subsets of NKG2DL genes in comparison to TMZ alone in GBM cells isolated from patient derived xenografts (PDX): 1) MICA and MICB were increased at least 10-fold in D456 (proneural) cells; 2) ULBP1 and ULBP2 were increased at least 2-fold in JX39 (classical) cells; and 3) minimal increases in NKG2DLs were observed in JX22 (mesenchymal) cells. Repression of NKG2DLs by hypoxia/low glucose was also heterogeneous, being observed in two of three GBM models tested. We are currently determining whether these combinatorial treatments improve gamma delta T-cell cytotoxicity against GBM cells and in vivo tumor models. Taken together, our data suggest that enhancing cell stress responses induced by chemotherapies may permit novel immunotherapy therapeutic interventions for brain tumor patients.

Bartonella henselae masquerading as possible gamma–delta T-cell lymphoma in a paediatric patient with 22q11.2 deletion syndrome

A 14-year-old boy with 22q11.2 deletion syndrome and a right ventricular to pulmonary artery xenograft conduit presented to an Australian tertiary children’s hospital with prolonged fevers, weight loss, splenomegaly and a high proportion of gamma–delta T cells in peripheral blood and bone marrow, concerning for possible gamma–delta T-cell lymphoma. However, investigations did not reveal evidence of lymphoma or autoimmune disease. After 5 months of intermittent fever episodes and ongoing symptoms, he was found to have an extremely high Bartonella henselae titre (8192) on serological testing, with the organism also detected on blood PCR. After 6 months of oral azithromycin and rifampicin, with complete resolution of his symptoms 3 months into treatment, his blood PCR was negative and gamma–delta T cells in peripheral blood were decreasing. The B. henselae titre remained unchanged for some time, but decreased to 2048 around 1 year after treatment was started.