Elution of anti-Zwa (-PIA1) from autologous platelets after normalization of platelet count in post-transfusion purpura.

In two patients suffering from post-transfusion purpura, anti-Zwa was demonstrated in either eluates from autologous platelets harvested during the remission phase and after normalization of the platelet count. In both patients, platelet-associated immunoglobulin (PAIg) was demonstrated during the acute phase. PAIg disappeared concomitantly with recovery and, thus, seems to be associated with the thrombocytopenia. These data support the assumption that immunocomplexes are adsorbed nonspecifically to the platelets and cause destruction of autologous platelets lacking the corresponding antigen. An association between the IgG3 subclass of anti-Zwa antibodies and the destruction of autologous platelets was also seen.