Autoantibodies and anti-mouse antibodies in thrombocytopenic patients as assessed by different MAIPA assays.

Two MAIPA (monoclonal antibody [MAb] immobilization of platelet antigen) assays were performed to determine (a) autoantibodies to platelet glycoproteins (GP) and (b) serum antibodies recognizing mouse MAbs used in the assay. In MAIPA I, control platelets were incubated simultaneously with human serum and a mouse MAb to a platelet glycoprotein (GP IIb-IIIa, Ib-IX, Ia-IIa, IV and p24). In MAIPA II, the control platelets were incubated first with the human serum and then, after washing, with the selected mouse MAb. A series of 25 patients with autoimmune thrombocytopenic purpura (ATP) associated or not with other autoimmune states were examined. Autoantibodies (both MAIPA I and MAIPA II positive) or anti-mouse Abs (MAIPA I positive and MAIPA II negative) were frequent in both groups of patients. Statistically significant differences existed in the incidence of anti-mouse Abs between patients (56.5%) and healthy donors (10%). This suggests that their production may be related to thrombocytopenias associated with autoimmune disease. We speculate that the presence of anti-mouse antibodies could reflect an abnormality in the immunological modulation of the idiotypic network.