CD4 and Autoimmunity: In addition to the conventional CD4+ subsets of Th1 and Th2 cells, additional subsets of Th17 and CD25+FOXP3+Tregulatory cells were discovered initially in models of autoimmunity[9] followed subsequently in various human diseases including autoimmune states[10] and infectious diseases caused by mycobacteria [11], respiratory syncitial virus [12] and HIV [13].