title: Participation of class II alloantigens in in vivo regulation of K/D region disparate thyroid graft rejection in mice.
abstract: Class I and II molecules preferentially activate cytotoxic T cells and helper T cells, respectively, in primary in vitro alloactivation of T lymphocytes. Collaboration between these subpopulations leads to an efficient anti-class I specific cytotoxic response. We tested whether the presence of class II, in addition to class I, alloantigens on thyroid allografts in vivo induces augmentation of anti-class I antigen immune response and leads to rejection of K/D region disparate grafts which otherwise would have been accepted. Different pairs of K or D region disparate mouse strains were selected in which transplantation across a class I antigen disparity alone resulted in long-term graft acceptance. In some pairs of mouse strains, co-transplantation of recipient mice with a second thyroid graft sharing the K/D region of the first, but additionally expressing an allo class II molecule, led to accelerated K/D region disparate thyroid graft rejection. Transplantation of thyroid allografts expressing both class II and I alloantigens did not induce increased host anti-class I antigen cytotoxic response, or affect the frequency of specific precursor cytotoxic T cells. In one pair of congenic mouse strains, acute rejection of K/D region disparate thyroid grafts occurred in the absence of class II alloantigen stimulation; in other strains, co-transplantation of class I and II alloantigen disparate thyroid allografts was not sufficient to induce K/D region disparate graft rejection. The results thus demonstrate that a class II alloantigen on a thyroid graft may augment the rejection response directed against the graft class I alloantigens. The class II alloantigen stimulation was not always essential or sufficient for induction of class I antigen disparate thyroid graft rejection, and was dependent on the specific I region and/or K/D region gene allele.
authors.forename: N
authors.initials: N
authors.lastname: Isakov
authors.forename: F H
authors.initials: FH
authors.lastname: Bach
mesh_terms: D000818:Animals; D003602:Cytotoxicity, Immunologic; D005802:Genes, MHC Class II; D006084:Graft Rejection; D006183:H-2 Antigens / Q000235:genetics* / Q000276:immunology; D064532:Histocompatibility Antigen H-2D; D008211:Lymphocyte Cooperation; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D011995:Recombination, Genetic; D013601:T-Lymphocytes / Q000276:immunology*; D013961:Thyroid Gland / Q000637:transplantation*
chemical_list: D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D