Abstract

Indirect platelet suspension immunofluorescence test was performed in sixty-seven patients with thrombocytopenia. Clinical diagnoses were idiopathic thrombocytopenic purpura (ITP) in 17, multiple transfusion in 16, systemic lupus erythematosus in 8, rheumatoid arthritis in 2, autoimmune hemolytic anemia in 1, malignant lymphoma in 1, multiple myeloma in 1, neonatal thrombocytopenia in 1, and non-immune thrombocytopenia in 20. The results are as follows: 1) Antiplatelet antibodies were positive in 2 of 17 cases with ITP (12%) 2) Of 13 cases with autoimmune thrombocytopenia other than ITP, antiplatelet antibodies could be detected in 4 cases (31%). 3) Antiplatelet antibodies were detected in 5 out of 16 cases with multiple transfusions. HLA antibodies were detected in 3 and platelet-specific antibodies in 2 among 5 cases with positive antinlatelet antibodies. 4) Among 11 cases with positive antiplatelet antibodies, IgG antibodies were detected in 8 (73%), IgM antibodies in (18%), and IgG puls IgM in (9%). 5) In one case of SLE with positive antiplatelet antibody, an increase in platelet count was observed, being antiplatelet antibody negative during therapy with prednisolone. 6) Of 20 cases with non-immune thrombocytopenia, all were negative in indirect platelet suspension immunofluorescence test. On the basis of these findings, it was considered that the indirect platelet suspension immunofluorescence test would be a useful method for detection of platelet autoantibodies and alloantibodies. IgM agglutinins, IgG non-agglutinating antibodies, platelet-specific antibodies, and HLA antibodies were also detectable with this method.