Complement activation in patients with Gambian sleeping sickness.

Low levels of complement components C3, C4 and factor B were found in the sera of most patients with early and advanced Gambian trypanosomiasis. C3 levels increased after treatment with melarsoprol (Mel B). Nearly all patients had high serum IgM levels and a significants correlation was found betwen high serum IgM levels and low serum C3 levels. High concentrations of cryglobulins, which contained IgM and C3, were found in most of sera tested. Formation of large molecular weight IgM complexes may play an important part in producing the low C3 levels found in patients with Gambian sleeping sickness.