Trypanosome non-specific IgM antibodies detected in serum of Trypanosoma congolense-infected cattle are polyreactive

Serum Ig from Trypanosoma congolense-infected cattle were affinity-purified using immobilised trypanosome or non-trypanosome antigens (beta-galactosid ase, cytochrome C and ferritin). The bound and unbound IgG and IgM fraction s were collected and tested in ELISA for reactivity to each antigen. The re sults indicated that the presence of reactivity to non-parasite antigens in serum of infected cattle is due to polyreactive IgM antibodies. However, t he IgG fraction only bound to trypanosome antigens and was only present in post-infection sera, indicating that it was induced by the infecting trypan osomes. Since the polyreactive IgM antibodies were also present in preinfec tion sera, it is probable that they were natural antibodies that were not i nduced but only amplified by the trypanosome infection. (C) 1999 Elsevier S cience B.V. All rights reserved.