Frequencies of lymphoid T-follicular helper cells obtained longitudinally by lymph node fine-needle aspiration correlate significantly with viral load in SIV-infected rhesus monkeys

Background T-follicular helper (T-FH) cells are an important population in lymph nodes (LNs) contributing to the generation of highly specific B cells. For SW studies in rhesus macaques (RM.), analysis of LN is necessary, but restricted due to invasive sampling. We applied the minimally invasive LN fine-needle aspiration (LN-FA) and examined dynamics of T-FH cells during SW infection. Materials and methods LN-FNA and LN resection were carried out on uninfected RM. Lymphocytes were analyzed by flow cytometry. Additionally, cells obtained by LN-FNA over time from SIV-infected RM were analyzed. Results Percentages of lymphocyte subsets were similar in LN aspirates and whole LNs. Analysis of LN aspirates from SIV-infected RM demonstrated a decrease of CD4(+) T cells, while T-FH cell frequencies increased over time and correlated significantly with plasma viral load. Conclusions By applying LN-FNA, we showed that T-FH cell expansion in chronic Sly infection is associated with viral load.