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HLA‐DR expression by platelets in acute idiopathic thrombocytopenic purpura
Author(s) -
Boshkov Lynn K.,
Kelton John G.,
Halloran Philip F.
Publication year - 1992
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1992.tb02991.x
Subject(s) - thrombocytopenic purpura , platelet , medicine , immunology , human leukocyte antigen , purpura (gastropod) , biology , antigen , ecology
Induction of expression of MHC class II antigens on the surface of cells that do not ordinarily express these proteins has been implicated in the pathogenesis of autoimmunity in diabetes mellitus and autoimmune thyroiditis. Platelets express class I but not class II HLA antigens. In this report, we describe a child with acute idiopathic thrombocytopenic purpura who at the time of the thrombocytopenic episode had class II (HLA‐DR) antigens on his platelets. Following recovery, the HLA‐DR antigens were no longer present on the platelets. We postulated that class II had been induced on his megakaryocytes by a cytokine such as interferon gamma, and that the induced expression of class II antigens contributed to the autoimmune disorder. To substantiate this possibility we next studied class I and II antigen expression on an erythroleukaemia cell line (HEL), which has many megakaryocytic features. Following treatment of HEL cells with interferon gamma, class I expression was increased and HLA‐DR antigens were induced. These observations suggest that cytokine‐mediated induced HLA‐DR expression may contribute to the pathogenesis of a subset of thrombocytopenias.