Frequency of circulating iNKT cells among Iranian healthy adults.

BACKGROUND Invariant natural killer T cells (iNKT) are a small subset of T lymphocytes which are involved in a wide variety of immune responses. Human studies have reported a wide variation in the number of circulating iNKT cell among healthy donors as well as in some immunologic disorders while there is no or little data about the factors which affect the pool of circulating iNKT cells in human. Given the importance of iNKT cells in immunologic responses and variation in the number and phenotype of iNKT cells, the aim of this study was to evaluate the frequency of circulating iNKT cells in a cohort of healthy Iranian adults. METHODS The number of circulating iNKT cells was measured among PBMC in a group of healthy Iranian adults by flow cytometry. iNKT cells were identified by using 6B11 monoclonal antibody or by coexpression of TCR Valpha24 and Vbeta11 chain. RESULTS The mean frequency of 6B11-iNKT cells and Valpha24-Vbeta11 iNKT cells among T lymphocytes, were 0.54% and 0.31%, respectively. Forty-five percent of 6B11-iNKT cells were CD4 positive, and there was a weak but significant inverse correlation between total 6B11-iNKT cells and their CD4-positive subset. There was no significant difference in the frequency of iNKT cells between males and females. CONCLUSIONS Results of this study show that the frequency of iNKT cells is fairly high among the Iranian population and suggest matching of study population for age, sex, and ethnic background in iNKT-related research. More studies are necessary to understand the factors that can affect the variation in the number of iNKT cells in healthy humans.