Effectiveness of Splenectomy and Platelet Autoantibodies.

The role of the spleen in pathophysiology of Idiopatic Thrombocytopenic Purpura (ITP) remains incompletely defined. Splenectomy has a fairly favourable initial response rate of 60% to 80%, and the longer the follow-up, the lower the success rate. As yet, there is no consistently effective method of predicting an individual response to splenectomy. So far not many observations have been published and if so, they were based on very small groups of ITP.

The aim of this work was to evaluate the response to splenectomy in 151 patients with ITP in relation to the detection of platelet autoantibodies. 151 ITP patients before and after splenectomy were observed for a period of 16 years.

Autoantibodies were examined by the platelet immunofluoresce test (PIFT) and/or by the monoclonal antibody immunobilization of platelet antigen (MAIPA) assay, sometimes in addition the HPA genotyping was performed using the PCR.

The response to splenectomy was regarded to be very good if platelet count was >150 G/l during at least 6 months follow-up. However, some patients were followed-up even for 15 years. Overall, platelet antibodies were detected in 34.3% (52/151) of patients. In 76% out of 52 patients the antibodies were detected by PIFT, in 63% by MAIPA; both tests were positive in 27% of patients. Most antibodies reacted with GPIIbIIIa.

Splenectomy was effective in 57% (30/52) of patients with antibodies and in 75.8% (75/99) of patients without detectable antibodies (p<0.01). In the effective splenectomy and antibodies group, in 23 patients the antibodies were examined during a follow-up and in 10 of them (43.5%) were not detected. In the uneffective splenectomy group only in 4 out of 18 (22.2%) examined patients the antibodies were not found. The differences between these groups were not significant.

Our data show that autoantibody platelet examination is not very helpful for predicting the effectiveness of splenectomy.