Variant class II molecules from H-2 haplotypes in wild mouse populations: Functional characteristics of closely related class II gene products

Independently derived haplotypes found in wild populations of mice often express class II molecules antigenically related to specific alleles of the A molecules defined in laboratory mice. Tryptic peptide fingerprint comparisons of these antigenically related molecules indicate that they have similar, or possibly identical, primary structures in the A(α), A(β), or both subunits. By using the A(k) and A(p) families of independently derived, antigenically related A molecules, the authors examined the effect that minor structural variations in the A molecule have on allorecognition by T lymphocytes. Data obtained indicate that a) minor structural variations in the A molecule can effect, although not always, major functional changes in allorecognition, b) changes in allorecognition are always detected when the A(β) subunit contains structural variations, but not necessarily when the A(α) subunit contains structural variations, and c) more than one site in the A molecule can be recognized by alloreactive T lymphocytes. These results can be interpreted as indicating that specific sites within the A molecule are critically involved in allorecognition and that structural variations must affect these sites to elicit major changes in allorecognition.