Expansion of cytotoxic CD4 T-cell clusters in lymph nodes of patients with Common Variable Immunodeficiency

Methods

Sorted TFH cells from CVID lymph nodes and healthy control tonsils were analyzed by bulk-RNA-sequencing. Altered protein expression was verified by flow cytometry and CyTOF analysis. Tissue localization of cells was determined by multi-fluorescence imaging.

Results: Transcriptome analysis of sorted TFH cells revealed an enrichment of cytotoxicity-associated gene sets in CVID patients. Extended immune phenotyping identified different cytotoxic CD4 memory populations expressing T-bet, EOMES, CRTAM, Perforin, and Granzyme A and B. Two clusters co- expressing markers of TFH differentiation such as CXCR5, ICOS, and PD1 were expanded in CVID lymph nodes. One of them additionally expressed high levels of FoxP3.

Histological sections confirmed the increase in Granzyme-B+EOMES+ CD4 cells in GCs of patients’ lymph nodes. Only few of these cells circulate in peripheral blood. Discussion: Our study reports for the first time that the previously reported type 1 polarization in lymph nodes of CVID patients is associated with an expansion of two distinct cytotoxic CD4 TFH cell clusters within GCs which were very rare in peripheral blood.

Further investigations directly in secondary tissues are required to explore their role in the GC failure in CVID.