FIG 6.

The synthesis of IgG Abs specific for T. brucei VAT 10-26 or VAT x is affected by a deficiency of CD4⁺ T cells but not by a deficiency of CD8⁺ T cells. Groups of 4 CD4^−/− (△), CD8^−/− (□), or wild-type (●) BALB/c mice were infected with 10³ T. brucei VAT 10-26 parasites. Another group of 4 CD8^−/− mice (○) was infected with 10³ T. brucei VAT 10-26 parasites and was treated with 1, 0.5, 0.5, 0.5, and 0.5 mg of a rat anti-mouse CD4 MAb (clone GK1.5) on days −2, 1, 8, 15, and 22 after infection, respectively. Plasma samples were collected from the infected mice on days 0, 6, 17, 27, 38, and 45 after infection or at the terminal stages (T). The levels of Abs specific for T. brucei VAT 10-26 (A) or VAT x (B) in plasma were measured by ELISA. Data are presented as means ± SEM and are representative of results from two separate experiments.