CD4+CD25(hi) regulatory T cells in healthy males and females mediate gender difference in the prevalence of autoimmune diseases.

It is generally acknowledged that autoimmune diseases are more prevalent in females worldwide. These diseases are caused by interaction of genetic and environmental factors that result in the failure of immune mechanisms responsible for self-tolerance. One of these mechanisms includes regulatory T cells which play an essential role in maintaining peripheral tolerance. These cells are a subset of CD4+ helper T cells which express high levels of CD25 on their surface. These cells suppress cells of both innate and adaptive immune systems in an antigen nonspecific manner through cell-cell contact and production of cytokines. As females have a higher incidence of autoimmune diseases and regulatory T cells play a crucial role in preventing autoimmunity, it was reasonable to hypothesize that the females might have a lower number of T(reg) as compared to males.50 apparently healthy males and 47 females aged 19 - 26 years were recruited for the study. The percentage of regulatory T cells in their peripheral blood was determined using flow cytometery. Mann Whitney rank sum test was applied to estimate the significance of gender related difference in their frequency.Significant difference was observed in regulatory T cells percentages of males and females, p < 0.02 showing that there is a lower regulatory T cell percentage in females than in males (2.89 +/- 1.46% vs. 3.32 +/- 1.39%).This study shows a significant difference in the frequency of regulatory T cells among males and females which could be one of the reasons for increased predisposition of females to autoimmune diseases.