TRYPANOSOMA-CONGOLENSE - B-LYMPHOCYTE RESPONSES DIFFER BETWEEN TRYPANOTOLERANT AND TRYPANOSUSCEPTIBLE CATTLE

Trypanosomiasis is a serious constraint to Livestock production in sub -Saharan Africa. Some breeds of cattle are genetically more resistant. to the pathogenic effects of trypanosome infection. We measured B-fel l activation and the quantity and isotype of antibody produced at the cellular level in six trypanotolerant N'Dama and five trypanosusceptib le Boran cattle. The frequencies of spleen cells secreting total and p arasite-specific IgM and IgG were measured prior to and 16, 28, and 35 days after a primary challenge with Trypanosoma congolense. Boran cat tle had higher frequencies of splenic cells secreting IgM specific for trypanosome-derived variable surface glycoprotein (VSG), cysteine pro tease (congopain, CP), and heat shock protein (hsp70/BiP) and the nonp arasite antigen, ovalbumin, than did N'Dama cattle. In contrast, the n umber of VSG-specific IgG-secreting cells was significantly greater in N'Dama than in Boran cattle. During infection, low titers of anti-VSC IgM were detected transiently in the serum of all animals. However, N 'Dama had significantly more VSG-specific Ige in blood than Boran duri ng infection. The peripheral blood mononuclear cell population of N'Da ma cattle contained a higher percentage of surface IgM-positive B-cell s prior to and throughout infection than were found in the blood of Bo ran. In addition, during infection N'Dama cattle had more circulating lymphocytes that could be activated in vitro to undergo differentiatio n into IgM- and IgG-secreting cells. These findings demonstrate differ ences in the frequency of trypanosome-specific antibody-secreting cell s in the spleen and in the activation state of B-cells in the blood be tween N'Dama and Boran cattle during a primary infection with T. congo lense. (C) 1996 Academic Press, Inc.