Sorry, I really regret to stretch this thread even longer and to even correct such a highly accomplished contributor as Dr. Daskal, however, I think, his effort to compress a six hour lecture oversimplified some points: >I am not sure that you got it fully straight. So here ia a 6 hour >lecture block >condensed into 60 seconds: >HLA= Human Lymphocyte Antigens This is the equivalent to the mouse >(mammalian) MHC >( Major Histocompatibility Complex). MHC (all species if they have it), H-2 (mouse) and RT-1 (rat) refer to a gene cluster containing the (major) genes responsible for tumor and tissue rejection. As we know today many of the genes encode proteins which present peptide antigens to T-cells. These proteins are called HLA class I and class II in humans (or correspondingly in other species, like SLA in swine). In one sentence: MHC refers to genes, HLA to proteins. >The MHC contain three groups of genes: >class I, class II and clas III which control the following: >Class I & class II code for surface recognition molecules >class III codes for some complement components. I think a better definition for class III is the genes not involved in antigen presentation like TNF-a and some complement components. However, this definition is not perfect either, because it would exclude TAP-1 and LMP from class III, thus, a lot of people do not like the term MHC class III. (N.B. for non immunologists: TNF, LMP, TAP-1 are all encoded in the MHC, TNF-a is a cytokine, TAP-1 is peptide transporter to translocate peptides from the cytoplasma to the ER to be loaded on HLA class I molecules, LMP is involved in generating these peptides) >All nucleated cells express clas I MHC antigens on their surface >class II on some Bcells, and macrophages, acivated cells (Tcells) The list lacks the most prominent class II expressor: the dendritic cells. Also I was under the impression that most if not all B-cells express class II. (N.B. there are even more cell types expressing class II and class II expression is species dependent: activated mouse T-cells do not express class II) >In humans the HLA gene is located on chromosome #6. Class I genes code for >transplantation antigens A, B and C >Class II genes are DP,DQ, DR and DZ. Class III as we said are that >of the complement >system. >The difference between the mouse and the human "MHC" is that in the >human all the >genes are linerly arranged and uninterupted while in the mouse the >MHC the class I >genes are interupted by Class II and III. >Hope thatb his made is simple but not simpler. Good luck! > >Ierachmiel Daskal M.D. PhD. FCAP, FASCP >Chairman >Department of Pathology and Laboratory Medicine >(215) 456-6126 >Pager: 2-3559 >daskali@einstein.edu > > For all people still confused, I can recommend to go to the library and get Jan Klein's "Natural history of the MHC". Although clearly outdated (1986) this book is highly readable, covers all the questions discussed in this thread (in particular in the opening chapter about the discovery of the MHC) and is probably the most thorough work ever done about this topic (the list of references is virtually endless and all references are sorted according to topics). yours Ulrich Beutner -- ================================================ Ulrich Beutner, Ph.D. Chirurgische Universitaetsklinik Abt.: Exp. Transplantationsimmunologie (ETI) (University Hospital, Department of Surgery Unit for Experimental Transplantation Immunology) Josef-Schneider-Str. 2 97080 Wuerzburg Germany beutner@chirurgie.uni-wuerzburg.de Tel. ++49 931 201-2252 FAX: ++49 931 201-3448 (or 2249) =================================================
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