Immunoregulatory abnormalities in Evans syndrome.

Immune function in six patients with Evans syndrome (Coombs-positive hemolytic anemia and immune thrombocytopenia) was compared to that in seven with chronic ITP. The two groups differed in measurements of T-cell subsets and immunoglobulin production. Evans syndrome patients had decreased T4 (T-helper) (P = 0.025), increased T8 (T-suppressor) (P = 0.008), and a decreased ratio of T4:T8 cells (P = 0.0009) when compared to controls. Results in chronic ITP patients were similar to those in controls. Serum IgG, IgM, and IgA levels and in vitro synthesis of IgG and/or IgM were decreased in most Evans syndrome patients. Diminished in vivo and in vitro immunoglobulin synthesis in Evans syndrome is consistent with the decreased T4:T8 ratio in these patients. The altered T4:T8 ratio may represent an unsuccessful response to an autoimmune process in which the trigger is unknown.