The T-cell receptor recognizes nominal and self antigen independently. A theoretical alternative to the modified self concept

Mls and the helper T-cell repertoire. I. Mls as a regulator of T-helper cell activation

We provide evidence that the Mls reaction involves a broad cross-section of the helper cell population. In addition to those cells reacting overtly to Mls stimulatory spleen cells, there is a second large population of helper cells that are affected by an Mls difference. This latent Mls effect is manifested by either synergy or antagonism in mitogen-mediated, Ia-dependent T-cell activation, depending on Mlsa or Mlsb phenotypes of stimulator cells, respectively. Our data can be explained by attributing to Mls alleles the function of differential regulation of autoreactivity of T cells. The results show that the concept of the Mls exerting a negative signal deserves serious consideration.

Mls and the helper T-cell repertoire: II. Does the Mls gene product influence the formation of the T-cell repertoire? Studies with Mls tolerance

In the formation of a repertoire, T cells are selected through a window of autoreactivity which is defined by a low boundary representing the minimal autoreactivity required to enter the T-cell compartment and a high boundary which determines the highest admissible autoreactivity. We propose that the Mls gene product down regulates autoreactivity and thus modifies the formation of the T-cell repertoire. Given the polymorphism of Mls and the assumption that Mlsb is more inhibitory than Mlsd, it is conceivable that Mlsb (responder) mice admit into their T-cell compartment T cells with higher autoreactivity than Mlsd mice. We suggest that it is this highly autoreactive fraction of Mlsb T cells which responds in the overt Mls response. We show that Mls tolerance eliminates T cells responding in the overt Mls response but not T cells responding in the latent Mls response. This is consistent with the finding that T cells responding in the latent Mls response occur in Mlsb as well as in Mlsd mice.