Immunoglobin M and malarial antibody levels in hyper-reactive malarial splenomegaly

In a study of chronic splenomegaly in Kenya, hyper-reactive malarial splenomegaly, our preferred name for tropical splenomegaly syndrome, was diagnosed in 38 patients. This diagnosis was based on exclusion of other conditions and observations of hepatic sinusoidal lymphocytosis on liver biopsy. To assess the previously recommended diagnostic criterion of elevation of serum IgM, to two standard deviations (s.d.) above the local mean, serum IgM levels were measured in patients and in 90 geographically matched controls. Patients with IgM levels 2 s.d. above the local mean were compared with those with lower levels. No differences were found other than higher malarial antibody titres in the group with higher IgM levels. Agreement is required concerning diagnostic criteria for hyper-reactive malarial splenomegaly; other features of the syndrome may occur in the absence of marked IgM elevation.