Strains of Toxoplasma gondii used for tachyzoite antigens to stimulate spleen cells of infected mice in vitro affect cytokine responses of the cells in the culture.

Cytokine responses of lymphocytes against Toxoplasma gondii are usually studied by stimulating the cells from infected animals with tachyzoite lysate antigens (TLA) in vitro. We examined whether strains (genotypes) of the parasite used for TLA affect the production of IL-2, IL-4, IL-10 and IFN-gamma in the culture of spleen cells obtained from mice infected with the ME49 (type II) strain. The amounts of IL-2 and IL-4 detected in the culture supernatants following stimulation with TLA of the RH (type I) strain were significantly greater than those detected following stimulation with TLA of the ME49 strain at 2 and 4 weeks after infection, respectively. These results suggest that antigen variations among the strains of T. gondii affect cytokine production of lymphocytes of infected mice. Therefore, to obtain accurate information on cytokine production by immune lymphocytes of infected hosts, it is important to use the identical strain of T. gondii for both infection of animals and preparation of TLA to stimulate the lymphocytes in vitro.