Immunogenicity of four sequential polypeptides in inbred guinea-pigs and their recognition at the T lymphocyte and antibody levels.

Four sequential polypeptides containing equimolar amounts of tyrosine, glutamic acid, alanine and glycine were shown to be T lymphocyte-dependent immunogens in inbred guinea-pigs. Poly (Glu-Ala-Tyr-Gly) was immunogenic only in strain 2 guinea-pigs; poly (Glu-Tyr-Ala-Gly) and poly (Ala-Tyr-Glu-Gly) were immunogenic only in strain 13 guinea-pigs; and poly (Ala-Glu-Tyr-Gly) was immunogenic in both inbred strains. The specificity of immune recognition was probed at the T lymphocyte and humoral levels with the heterologous polypeptides. Only a few cases of heterologous cross-stimulation or cross-reaction were observed, indicating the great selectivity of immune recognition. The results showed considerable variability in immune recognition from animal to animal. Nevertheless, at the T-cell level, cross-stimulation appears to necessitate that the antigen is itself immunogenic in that strain, whereas at the antibody level, cross-reaction is not similarly restricted. The structural basis for mutual recognition of immunogen and antigen at these levels is discussed.