Immunodeficiency diseases and expression of HLA antigens.

The role of HLA antigens in lymphocyte differentiation is strongly suggested by the existence of a recently identified immunodeficiency associated with, and probably resulting from, the lack of expression of HLA-A, B, and C antigens as well as beta2 microglobulin on various cells of hematopoietic origin. This "bare lymphocyte syndrome" has been described in a family where the transmission appeared to be autosomal recessive, and the responsible gene was not borne by the sixth chromosome. Another infant with a severe combined immunodeficiency disease has been treated with fetal liver and thymus transplants (FLTT). A persisting chimerism has been documented: T cells derived from the donor and B cells from the host. Despite complete HLA-A, B, and DR mismatch, T and B cells did cooperate resulting in significant antibody production, and defense against viral infection has been normal. Such an observation may suggest that "allogeneic restriction" of T-cell effector functions can be circumvented.