Immunosuppressive properties of rabbit antibodies against a major glycoprotein restricted to rat leukocyte membranes.
The role of antibodies to the rat leukocyte-common (LC) antigen in the immunosuppression induced by antilymphocyte serum (ALS) was tested in two ways. First, two batches of rabbit antisera to purified rat LC antigen and a conventional rabbit anti-rat thoracic duct lymphocyte serum (ALS) were compared for their ability to suppress the rejection of LEW (RT1l) kidney grafts transplanted to DA (RT1a) recipients. All three sera were able to suppress rejection completely. However, when the amount of lymphocyte-binding immunoglobulin necessary for effective immunosuppression was compared, the anti-LC sera were found to be 10-fold weaker than the conventional ALS. In the second experiment the conventional ALS was depleted of its anti-LC antibodies by incubating with pure LC antigen, and this was found not to diminish its immunosuppressive potency. It was concluded that anti-LC antibodies do not contribute significantly to the immunosuppressive potency of conventional ALS. This is despite the fact that anti-LC antibodies constituted 48% of the antibodies in the ALS used in the immunosuppression experiments, and in six other batches of ALS the proportion of anti-LC antibodies ranged from 25 to 49%. Because only a small component of the nonanti-LC antibodies are directed at leukocyte-specific antigens, it is concluded that the immunosuppressive properties of ALS are mediated by a minor component of the serum directed at as yet undefined antigens. In additional experiments, a mouse monoclonal antibody to the rat LC antigen, a mouse monoclonal antibody (W3/13) to a rat T lymphocyte-brain-granulocyte antigen, and rabbit antisera to pure rat Thy-1 were tested for their ability to suppress kidney graft rejection, but none had any effect at all, even in large doses.
Fabre
J W
JW
Nuffield Department of Surgery, John Radcliffe Hospital, Headington, Oxford OX3 9DU, England.
Sunderland
C A
CA
Williams
A F
AF
D000818:Animals; D000961:Antilymphocyte Serum / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D006085:Graft Survival / Q000187:drug effects / Q000502:physiology; D016030:Kidney Transplantation / Q000276:immunology*; D017493:Leukocyte Common Antigens / Q000276:immunology; D007962:Leukocytes / Q000187:drug effects / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000276:immunology; D051379:Mice; D011817:Rabbits; D051381:Rats; D011917:Rats, Inbred Lew; D014184:Transplantation, Homologous; D014508:Urea / Q000097:blood
D000961:Antilymphocyte Serum; D008562:Membrane Glycoproteins; D014508:Urea; D017493:Leukocyte Common Antigens