title: Recipient humoral immunity against leukoreduced allogeneic platelets is suppressed by aminoguanidine, a selective inhibitor of inducible nitric oxide synthase.
abstract: Leukoreduced allogeneic platelet transfusions have been previously shown to initially stimulate an in vitro cellular cytotoxicity and subsequently Induce the formation of immunoglobulin G (IgG) antidonor alloantibodies. To further characterize these responses and determine if they are related, recipient BALB/c H-2d mice were treated with aminoguanidine (AMG), a selective inhibitor of inducible nitric oxide synthase (iNOS), and transfused weekly with 2 x 10(8) C57BL/6 H2b platelets. In control, non-AMG-treated mice, transfusion significantly (P < .01) increased serum levels of interferon-gamma (IFN-gamma) by day 1 posttransfusion (PT). IFN-gamma returned to pretransfusion levels by day 3 PT, and its production was not affected by AMG treatment. Serum interleukin-4 (IL-4), on the other hand, was undetectable before and during the transfusion protocol. By day 3 PT, recipient spleen cells could mediate in vitro anti-P815 (auto), anti-EL4 (allo), and anti-R1.1 (third-party MHC) cytotoxicity, and these responses were maximal by day 7 PT. Concurrently, a significant reduction in the vitro ability of recipient splenocytes to respond to Concanavalin A (ConA) was observed; this was not seen with lipopolysaccharide (LPS) stimulation. Elevated levels of NO2- were found in the ConA culture supernatants from transfused mice at day 3 PT. Serum antidonor alloantibodies were detected by the fifth platelet transfusion. AMG treatment of recipient mice significantly inhibited the transfusion. Induced cytotoxicity and ConA-stimulated NO2- production, and restored ConA-induced proliferation to normal levels. AMG appeared to selectively inhibit platelet-induced alloantibody production in that it did not affect antibody production induced by transfusions with 10(5) allogeneic leukocytes or by immunization with a foreign protein antigen, human gamma globulin, in adjuvant therapy. These results indicate that an in vivo AMG-sensitive mechanism is essential for recipients to initiate a humoral IgG immune response against allogeneic platelets.
authors.affiliation: Division of Hematology, St Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Bang
authors.forename: E R
authors.initials: ER
authors.lastname: Speck
authors.forename: V S
authors.initials: VS
authors.lastname: Blanchette
authors.forename: J
authors.initials: J
authors.lastname: Freedman
authors.forename: J W
authors.initials: JW
authors.lastname: Semple
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D001792:Blood Platelets / Q000276:immunology*; D003208:Concanavalin A / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic; D004306:Dose-Response Relationship, Immunologic; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D006146:Guanidines / Q000494:pharmacology*; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis* / Q000276:immunology; D016756:Immunoglobulins, Intravenous / Q000276:immunology; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007371:Interferon-gamma / Q000097:blood; D015847:Interleukin-4 / Q000097:blood; D007518:Isoantibodies / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008212:Lymphocyte Depletion; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D017713:Platelet Transfusion; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology
chemical_list: D004791:Enzyme Inhibitors; D006146:Guanidines; D007074:Immunoglobulin G; D016756:Immunoglobulins, Intravenous; D007166:Immunosuppressive Agents; D007518:Isoantibodies; D008070:Lipopolysaccharides; D003208:Concanavalin A; D015847:Interleukin-4; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; C004479:pimagedine