Elevation of platelet-associated IgG in aplastic anemia.

We determined platelet-associated IgG (PAIgG) levels in patients with aplastic anemia, idiopathic thrombocytopenic purpura (ITP), iron deficiency anemia, and systemic lupus erythematosus (SLE), as well as in normal healthy adults as a control group. To determine PAIgG levels, we used a competitive micro enzyme-linked immunosorbent assay, which had excellent reproducibility, recovery, and dilution. We confirmed its reliability by comparing it to the immunoradiometric assay. Both the aplastic anemia group (n = 27, mean +/- SD = 218.6 +/- 244.6 ng/10(7) platelets) and the ITP group (n = 82, mean +/- SD = 212.5 +/- 327.8 ng/10(7) platelets) had higher PAIgG levels than the SLE group (n = 4, mean +/- SD = 38.4 +/- 22.4 ng/10(7) platelets), iron deficiency anemia group (n = 10, mean +/- SD = 16.1 +/- 3.6 ng/10(7) platelets), and normal control group (n = 69, mean +/- SD = 16.1 +/- 3.6 ng/10(7) platelets. The higher platelet-associated IgG levels in aplastic anemia suggest that autoimmune mechanisms are involved.