Remission of post-transfusion thrombocytopenic purpura with high dose intravenous corticosteroids

Immunoglobulin classes and subclasses of platelet antibodies in a case of post-transfusion purpura

A multiparous white woman developed severe thrombocytopenia following transfusion of red blood cells. Six ineffective platelet transfusions (a total of 42 random donor concentrates) were given from day 0 to day +6, high-dose steroids from day +1, progressively tapered until day +30, and a total of 150 g of intravenous immunoglobulins from day +2 to day +6. As platelet count had not increased significantly by day +8, four plasma exchange procedures, each consisting of 2,000 ml of plasma exchanged with 5% albumin solution, were performed on days +8, +10, +14 and +18. Platelet count was 5, 50, 100 and 234 x 10(9)/l on days +8, +14, +26 and +32 (discharge), respectively. The patient's acute phase serum contained increased levels of platelet alloantibodies with anti-HPA-1a (PlA1, Zwa) specificity and a titer of 3,200. IgG1, IgG2 and IgG3 subclasses of platelet-reactive antibodies in the patient's serum were elevated, whereas IgG4, IgM and IgA were within the reference values. Levels of IgG1, IgG2 and IgG3 of antiplatelet antibodies showed a marked and parallel reduction during treatment, but were still above the reference values at the end of treatment and 1 year later, when the patient platelet count was normal. Although a failure of intravenous immunoglobulins cannot be proven in this case, plasma exchange seems to have contributed more than intravenous immunoglobulins to clinical remission.

Post-transfusion purpura associated with alloimmunization against the platelet-specific antigen, Baka

Post-transfusion purpura (PTP) with severe thrombocytopenia occurred eight days after transfusion in a 28-year-old woman and responded to treatment with prednisone and plasma exchange. In contrast to nearly all previously studied cases of PTP, the patient's platelets were PlA1-positive and anti-PlA1 antibody could not be detected in serum obtained during the thrombocytopenic episode. Her serum was found to contain an antibody specific for a recently described platelet-specific alloantigen, Baka, in addition to multiple HLA-specific antibodies. The patient's platelets, typed following recovery, were Baka-negative. These findings indicate that post-transfusion purpura can occur in association with alloimmunization to platelet-specific antigens other than PlA1. In performing the serologic studies, a close relationship and possible identity between Baka and another recently reported platelet antigen, Leka, was observed. A method for analyzing mixtures of cytotoxic platelet-reactive antibodies without separating the individual antibodies is described.