Mls allo-determinants are recognized in an MHC class II antigen-dependent but unrestricted fashion by a discrete set of T cells.

Blocking studies carried out with anti-H-2 class II antigen antibodies show that H-2 class II molecules are intimately involved in the recognition of Mlsa determinants by unprimed, specifically responsive T cells. The blocking of the anti-Mlsa response by these antibodies were not due to inhibition of IL-1 production by H-2 class II antigen positive macrophages. A strain analysis indicates that the response to Mlsa is regulated by H-2-linked genes and that this effect is exerted at the level of the stimulator cells; however, the response to Mls epitopes does not appear to be H-2 restricted. Finally, the ability of spleen cells from Mls-incompatible mice to induce a state of Mls-specific, clonal deletion type tolerance by neonatal injection, shows that Mls determinants exist in qualitatively allelic forms and suggests that these determinants are recognized by specific clones of T cells.