Mitogenic stimulation of bovine peripheral blood mononuclear cells by Theileria sergenti antigen and inhibition by antibody from experimentally infected cattle.

Stimulation with a lysate of Theileria sergenti-parasitized red blood cells (PRBC) resulted in marked proliferation of normal bovine peripheral blood mononuclear cells (PBMC) in vitro. Partial inhibition of the proliferation was demonstrated by the addition of immunoglobulin (Ig) obtained from experimentally infected cattle when they revealed high levels of parasitemia and antibody titres. A mouse monoclonal antibody recognizing a 32 kDa antigen also showed inhibitory activity against the in vitro proliferation of bovine PBMC, but complete inhibition could not be achieved.