Genetic characterization of FLA, the cat major histocompatibility complex.

Abstract

The major histocompatibility complex (MHC) of the domestic cat (termed FLA) has been refractile to genetic and serological definition largely because of repeated failure to detect cytotoxic antibodies in multiparous cats or to elicit antibody following allogeneic lymphocyte immunization. We have developed a protocol for producing cytotoxic alloantisera in the cat following rejection of multiple surgical skin grafts. Of 59 cats subjected to grafting, 13 produced lymphocytotoxic antisera which had varying specificities among a panel of outbred cat cells. A population cluster analysis of the 13 alloantisera permitted the identification of six clusters of overlapping FLA specificities. The major histocompatibility complex (MHC) is a multigene cluster in mammals encoding two distinct classes of molecules involved in the presentation of foreign antigen to the T-cell receptor (1-5). Class I genes encode a 45-kDa glycoprotein that is noncovalently linked with an invariant light chain, P2-microglobulin (f82m), on the surfaces of virtually all nucleated cells (4, 6). Class II genes encode the heavy (32-35 kDa) and light (25-28 kDa) subunits of the noncovalently associated af3 heterodimeric glycoproteins expressed on the surfaces of antigen-presenting cells and activated T cells (5). By serological analysis, both class I and class II antigens are abundantly polymorphic in most outbred species. DNA restriction analysis has also revealed extensive polymorphism of the MHC of mice, humans, and several other species (7,8). The function of both class I and class II antigens is to present foreign, often viral, antigen to the T cell receptor. In this way, the cellular immune response is directed to parasitized cells instead of free virus particles (9,10).The domestic cat is an important model for at least two viral diseases of the immune system in humans, human T cell leukemia and acquired immunodeficiency syndrome (AIDS) (11,12). The characterization of the feline MHC as a prerequisite for the study of disease progression has been difficult because of an apparent inability to raise typing alloantisera in the cat (13 MATERIALS AND METHODSDetails of allograft transplantation are described elsewhere (ref. 21; C.W. and S.O., unpublished data). Briefly, split thickness skin grafts were surgically exchanged between selected cats at 21-day intervals. In some cases, intraperitoneal booster injections of peripheral blood lymphocytes (PBLs) from 15 ml of blood were performed at 4-day intervals after grafting (21). Serum was collected from graft cats weekly and used in a cat complement-dependent cytotoxicity assay. A modification of a two-stage assay using 51Cr release as an indicator ofcell death was used to detect alloantibodies against donor cat lymphocytes. The monoclonal antibody W6/32 (23), specific for human class I heavy chain, and the monoclonal antibodies IB5 (human DR and DQ specific) (24) and ISCR3 (mouse I-EK specific) (25) were used as positive controls in immunoprecipitation experiments.Interleukin 2-stimulated or fr...

DNA variation of the mammalian major histocompatibility complex reflects genomic diversity and population history.

“…The first species group included mouse and human, species with abundant functional MHC variability (12). The second group comprised 16 random-source domestic cats (Felis catus), a species that displays antigenic diversity at the MHC, termed FLA, but less than that observed in mouse or man (25). The third group included two populations of African cheetah subspecies, A. jubatus jubatus (South African) and A. jubatus raineyi (East African).…”

“…Conversely, species that have abundant MHC antigenic variability (mouse, pig, rat, and mole rat) show appreciable DNA variation. The domestic cat, which has an intermediate level of functional MHC polymorphism (25) After transfer, nitrocellulose filters were hybridized with MHC class I molecular clones derived from homologous species, i.e., 5'Db for mouse (21), HLAB7 for human (22), and pFLA24 for cat and cheetah (23). Cheetah diversity than 10 species of felids or other mammals similarly typed with 50 allozyme markers (26,27).…”

Comparative Genome Organization of Human, Murine, and Feline MHC Class II Region

“…2, 3). Loss of the DQ and DP genes may be the reason for a remarkable immunological "tolerance" seen in cats from several perspectives, including: (1) the lack of cytotoxic antibody production (including IgE) in multiparous cats (Pollack et al 1982;Winkler et al 1989), (2) very inefficient antibody induction; only 13 of 59 domestic cats (22%) produced detectable levels of antibodies following allogenic lymphocyte immunization and skin graft transplantation (Winkler et al 1989), and (3) a remarkable tolerance for allogenic bone marrow and tissue transplants among noninbred cats used in gene therapy protocols (Simonaro et al 1999;Sun et al 1999). The critical role of class II gene families in antibody production would support the notion that DP/DQ loss in domestic cats contributes to quantitative diminution of antibody recognition and induction.…”

Effects of Genotype Matching of Feline Major Histocompatibility Complex (FLA) Class II DRB on Skin-allograft Transplantation in Cats.

“…Winkler et al [20] have reported that skin-grafts transplanted between unrelated cats could not survive longer than 10 days. The cats used in the present study were all unrelated, so that we considered that the duration of skin-allograft survival might be prolonged by matching the types of DRB subgroups with the RT-PCR-RFLP method.…”