LEUKOCYTE PHENOTYPIC CHANGES IN AN IN-VITRO MODEL OF ABO HEMOLYTIC TRANSFUSION REACTION

BACKGROUND: ABO antigen-antibody interaction in the presence of periph eral blood leukocytes (white cells) results in the production of a var iety of proinflammatory cytokines. However, although tumor necrosis fa ctor cr has been shown to be derived al least primarily from monocytes , the range of cells activated by this process has not previously been reported. Therefore, changes in mononuclear cell surface antigen expr ession were studied, to determine which subsets of white cells appeare d to be activated in the setting of ABO incompatibility.STUDY DESIGN A ND METHODS: Group O peripheral blood mononuclear cells (PBMCs) were in cubated in autologous plasma with group A or O red cells (RBCs) for up to 24 hours. White cell expression of activation and adhesion markers was measured at 2 and 24 hours by flow cytometry, using direct or ind irect fluorescein or phycoerythrin labeling. RESULTS: Expression of ly mphocyte activation markers CD25, GDw108, and CD109 was equivalent whe n PBMCs incubated with group A and O RBCs were compared. However, afte r 2 hours, mean fluorescence of CD14 on PBMCs incubated with group A R BCs was 65 percent of that on PBMCs incubated with group O RBCs and re mained similarly decreased at 24 hours. CD44 expression was upregulate d on PBMCs exposed to both group A and O RBCs, but it was increased si gnificantly more on monocytes exposed to group A RBCs. The ability to bind hyaluronic acid was induced in approximately 42 percent of CD14monocytes exposed to group A RBCs but in no cells exposed to group O R BCs. CONCLUSION: Downregulation of CD14 and increased binding of hyalu ronic acid reflects monocyte activation in this model. No evidence of lymphocyte activation was found, supporting the hypothesis that ABO tr ansfusion reactions primarily activate monocytes.