Analysis of Ia-antigen(s) positive macrophages in experimental murine toxoplasmosis

Abstract The present study has demonstrated marked increase in the relative percentage of Ia-positive macrophages among the peritoneal macrophage population(s) of BALB/c mice infected intraperitoneally with Toxoplasma gondii or when chronically infected mice were rechallenged with Toxoplasma . The observed increase in Ia-positive peritoneal macrophage numbers coincided with the appearance of interferon-gamma (IFN-γ) in the sera of infected mice. The appearance of elevated serum IFN-γ titer was a temporary event but the increased percentage of Ia-positive macrophages persisted. The data presented have documented that antigen-specific proliferation response of vigorously purified Toxoplasma -sensitized T-cells is dependent upon Ia-bearing macrophages. This model is useful for future studies into various aspects of the interaction(s) between parasite antigens and Ia-antigen(s) at the macrophage surface for successful recognition of antigen-specific T-cells.