Lymphoid tissue inducer cells in adaptive CD4 T cell dependent responses.

Lymphoid tissue inducer cells (LTi) are known for their role in embryonic lymphoid tissue development. We have identified LTi in adult tissues including spleen and thymus, and provide evidence here for their presence in the submucosa of the intestine. From these observations it is clear that LTi play multiple roles in the adaptive immune system, notably the ability to recruit and sustain primed CD4 T cells in environments where they provide help to other cells. We speculate that their human equivalents could be potential targets for HIV infection and their destruction explains the pattern of loss of CD4 T cells.