MHC Class II Molecules Are Not Required for Survival of Newly Generated CD4+ T Cells, but Affect Their Long-Term Life Span

AbstractWe grafted fetal thymi from wild-type mice into immunodeficient RAG-2−/− or class II−/−RAG-2−/− (class II MHC−) recipients and followed the fate of naive CD4+ T cells derived from the grafts. In both types of recipients, newly generated CD4+ T cells proliferated to the same extent in the periphery and rapidly filled the empty T cell compartment. However, CD4+ T cells in class II− recipients gradually decreased in number over 6 months. These results show that interactions between the TCR and class II molecules are not required for newly generated CD4+ T cells to survive and proliferate, but are necessary to maintain the size of the peripheral T cell pool for extended periods