Clinical value of a direct platelet suspension immunofluorescence test in adult idiopathic thrombocytopenic purpura.

109 adult patients with ITP were tested with the direct platelet suspension immunofluorescence test (PSIFT) for platelet-associated immunoglobulins (PAIg). 88 patients (81%) had a positive direct PSIFT. The mean platelet level at the time of the test was 45.2 X 10(9)/l [corrected] (SD = 28.8) with no difference between PSIFT-positive and -negative groups. The results of direct PSIFT were of limited value in predicting patient outcome. The overall better prognosis of patients with a negative direct PSIFT compared to those with a positive result was statistically significant. The PSIFT negatives achieved complete remission more often than PSIFT positives; and they also showed a tendency for a better response to splenectomy and therapy with high-dose i.v.Ig. Moreover, all the 21 patients refractory to therapy with corticosteroids, splenectomy or i.v.Ig, were PAIg positives.