A Model Implicating Altered Macrophage Function in H-2 Linked Nonresponsiveness to Hen Lysozyme

Abstract

Studies on the basis of differential responsiveness of H-2 mice to gallinaceous lysozymes suggest T cell involvement and active T cell suppression with those lysozymes not responded to. Results from other laboratories suggesting a directive role for macrophages through limited presentation are summarized. A model is presented proposing that suppressors (recognizing a determinant only on lysozymes not responded to) are present in all strains; that suppression requires antigen bridging between suppressor determinant and positive T determinant; that this bridge is disrupted in all strains but H-2^b; and that this failure to disrupt the antigen bridge is a result of a genetically (la) controlled loss of a normal macrophage processing step.

It was found in our laboratory (Hill and Sercarz, 1975; Sercarz, et al. 1978) that in mice there is an H-2-1inked genetic control of the ability to differentially respond to a set of closely related gallinaceous egg-white lysozymes. In H₁-2^b animals, no response is found with lysozymes from chicken (HEL), bobwhite, Gambol or Valley quail and guinea hen; a good response obtained with lysozymes from Japanese Quail and ring-neck pheasant (REL); and a limited response with turkey and peafowl lysozymes. Using mice with other H-2 haplotypes essentially equal responsiveness is obtained with all the above lysozymes. Comparison of the sequences of these lysozymes, indicates that the only consistent difference is the presence of tyrosine at position 3 in those lysozymes responded to by H-2^b mice, with phenylalanine being present at position 3 in other lysozymes. Because of the limited response to turkey and peafowl, it would appear that in addition to the dominant effect of tyrosine-3, other substituents can have a modifying influence.

Responsiveness has been assayed in several ways: primary or secondary production of anti-lysozyme plaques; production of anti-lysozyme serum antibody; provision of help for an anti-TNP response; and through generation of T cells showing a proliferative response to antigen.