Periparturient reduction in buffalo of mitogen-induced lymphocyte proliferation and antibody to Toxocara vitulorum.

Lymphocyte and antibody reactivity were examined during the periparturient period in buffalo cows naturally infected with Toxocara vitulorum. Titres of antibodies to an extract of T. vitulorum larvae increased about 3 months before parturition. Antibody titres declined at about the time of parturition and remained low for up to 3 months into lactation. Lowered titres were found in the IgG class and not the IgM class of immunoglobulins. Levels of lymphocyte transformation induced by the mitogens concanavalin A and pokeweed mitogen declined markedly from one to 2 weeks before until one to 2 weeks after parturition. The relationship between this suppressed immunological reactivity and vertical transmission of T. vitulorum larvae is discussed.