CD8 T_FR induces T_FH apoptosis via HLA-E.

<p>Human tonsil cells were sorted to isolate CD8 T_FR, CD8 conv, and T_FH, spinoculated with R5-tropic HIV, and cultured for 2 days. (A) Representative flow plots showing the percent of Annexin-V+ T_FH in co-culture at 1:1 ratio with CD8 T_FR or CD8 conv 2 days after R5-spinoculatoin. (B) Results from a total of 6 tonsil for mock-, X4-, and R5-spinoculation (isotype n = 3) in A. Co-cultures were also performed with HLA-E blocking antibody or isotype controls (500 ng/μl). (C) Number of T_FH per microliter on day 0 and day 2 when cultured alone (circle, triangle), 1:1 with CD8 T_FR (square), or 1:1 with conventional CD8 T cells (upside down triangle) (n = 6). Statistical significance was determined by Wilcoxon matched-pairs tests and is displayed as * = p<0.05 and ** = p<0.01.