title: Inhibition of T- and B-lymphocyte functions by normal immunosuppressive protein.
abstract: Normal immunosuppressive protein (NIP) isolated from human plasma was studied in two well defined systems. (1) Spontaneous rosettes of sheep red blood cells with human peripheral blood lymphocytes and PHA-induced lymphocyte cytotoxicity as indicators for T-cell function. (2) Rosette formation tests of human lymphocytes with antibody-coated erythrocytes or erythrocytes coated with antibody and complement as well as antibody-induced lymphocyte-mediated cytotoxicity represented non-T-cell activity. While NIP did not inhibit the formation of any of the above mentioned rosettes, it practically prevented both PHA-induced and antibody-mediated lymphocyte cytotoxicity. Relatively small amounts of NIP inhibited PHA-induced cytotoxicity while higher doses were required for the inhibition of antibody-mediated lymphocyte cytotoxicity. Possible mechanisms of its suppressive activity are discussed. NIP was found to be heat-stable and did not show any species specificity, as NIP preparations from human plasma were immunosuppressive in human, mouse and guinea-pig systems.
mesh_terms: D000510:Alpha-Globulins; D000818:Animals; D000906:Antibodies; D001402:B-Lymphocytes / Q000187:drug effects*; D003601:Cytotoxicity Tests, Immunologic; D004912:Erythrocytes / Q000276:immunology; D006168:Guinea Pigs; D006801:Humans; D007104:Immune Adherence Reaction; D007114:Immunization; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D037102:Lectins; D051379:Mice; D012756:Sheep / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects*
chemical_list: D000510:Alpha-Globulins; D000906:Antibodies; D007166:Immunosuppressive Agents; D037102:Lectins