V beta selective elements: self and non-self

Over the last four years, a number of potent T cell responses have been shown to be determined by that portion of the T cell receptor encoded in the V beta gene segment. Responses are essentially uninfluenced by junctional sequences in the beta-chain or by the nature of the alpha-chain. These responses also involve the class II MHC molecule expressed on a stimulating antigen presenting cell. The principle stimuli that have been studied are the polymorphic Mls loci in the mouse and a series of toxic proteins secreted by bacteria, now known as superantigens. Here, some aspects of stimulation by what we call V beta selective elements will be analyzed. The nature of stimulation by self V beta selective elements will be discussed and compared to that of non-self V beta selective elements. It will be shown that the similarities are extensive, including a preference for murine I-E molecules and a hierarchy in the effectiveness of murine I-A molecules in presenting V beta selective elements to certain T cell receptors.