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

The therapeutic value of HPA-1a-negative platelet transfusion in post-transfusion purpura complicated by life-threatening haemorrhage

Post-transfusion purpura (PTP) was diagnosed in a female patient 1 week after transfusion for hysterectomy. Despite treatment with oral steroids and intravenous immunoglobulin, platelet counts remained low, and the patient developed profuse rectal bleeding. Random platelet transfusion is reported to be ineffective in PTP. We report a case in which the transfusion of HPA-la negative platelets provided good increment and clinical haemostasis before intravenous immunoglobulin could have had an effect.

Frozen platelet plates for platelet antibody detection and cross-match

We performed 2 studies aimed at developing a frozen platelet panel suitable for platelet cross-matching. The stability of the most important platelet membrane glycoproteins and the reactivity of antigens of the human platelet antigen (HPA) and of the human leukocyte antigen (HLA) systems were evaluated with the platelet suspension immunofluorescence test (PSIFT) in a panel of platelets frozen in microplates with 6% dimethylsulfoxide. In study No. 1 we evaluated platelet reaction with a broad-spectrum weak anti-HLA and a potent anti-HPA-1a antiserum and the expression of glycoproteins Ib and IIb/IIIa complex on platelet membrane before freezing and after 0.5, 1, 2, 3, 4, 5, 6 and 12 months of storage at -80 degrees C. In study No. 2 we examined platelet reactivity with anti-HPA-1b, -HPA-2a, -HPA-3a, -HLA-A2, -HLA-A3 of platelets stored frozen for 12 months in parallel with fresh platelets from the same donors. Study No. 1 showed that glycoprotein expression was stable and that the weak anti-HLA and the potent anti-HPA-1a antibodies were clearly detected during 12 months at -80 degrees C. Of the 35 paired PSIFT performed in study No. 2 with fresh and frozen/thawed platelets incubated with anti-HPA-1b, -HPA-2a, -HPA-3a, -HLA-A2, -HLA-A3 antisera and AB serum, concordant reactions were obtained in all cases with the exception of 1 case of HLA-A3-positive platelets incubated with anti-HLA-A3 antiserum, that was reactive with frozen/thawed platelets but nonreactive with fresh platelets from the same donor.(ABSTRACT TRUNCATED AT 250 WORDS)

Post-transfusion purpura: a survey of 12 Danish cases with special reference to immunoglobulin G subclasses of the platelet antibodies

The clinical and immunological data of 12 Danish cases of post-transfusion purpura (PTP) are summarized. All patients but one were women. All except one had thrombocytopenic purpura which occurred 4-11 days after transfusion, usually with a nadir of the platelet count below 10 x 10(9) 1(-1). The typical haemorrhagic symptoms were cutaneous bleedings, melena and haematuria lasting from 3 to 12 days. The time until normalization of platelet count varied from 3 to 50 days after onset. One patient had recurrence of PTP and one patient died due to intracranial haemorrhage. Ten of the HPA-1a negative patients (83%) had platelet-specific HPA-1a antibodies and two HPA-1a positive individuals had anti-HPA-1b antibodies. In 10 patients, HLA antibodies were also detectable and in one patient a delayed haemolytic transfusion reaction due to anti-E was seen. All of seven patients investigated had anti-HPA antibodies of both IgG1 and IgG3 subclasses during the thrombocytopenic period while all of 10 patients had anti-HPA of only the IgG1 subclass after recovery from PTP. Thus, the destruction of autologous platelets in PTP seems to be associated with the presence of anti-HPA of the IgG3 subclass which may be of importance in the pathogenesis of PTP.