Diagnostic and prognostic significance of platelet-bound IgG measurement in immune thrombocytopenic purpura.

Abstract

The test proposed by Dixon et al. is an important contribution to the technique for detection of platelet-associated antibody. This test measures platelet-associated IgG by a complement-mediated red blood cell lysis-inhibition technique. We have used the direct Dixon test to study 44 cases of immune thrombocytopenic purpura and 90 controls, including subjects with nonimmune thrombocytopenic purpura and healthy subjects. Increased PAIgG was noted in 86.3% of ITP patients. However, the pretreatment values of PAIgG were not helpful for predicting the therapeutic response to either prednisone or splenectomy. Six patients in long-term clinical remission had normal platelet counts and distinctly abnormal PAIgG values. This condition was associated with qualitative platelet functional defects. This latter finding seems to be of diagnostic interest and deserves further investigations.