Infection of human macrophages with resistant or susceptible L. (V.) braziliensis or L. (L.) amazonensis isolates. Human Mφ from 3 healthy donors were infected with NO•-susceptible or NO•-resistant L. (L.)amazonensis or L. (V.) braziliensis and evaluated at the designated time points for the level of intracellular infection. After monolayers were stained with Giemsa, the level of infection was expressed as number of amastigotes per 100 Mφ (A, B), and as the percentage of infected Mφ (C, D) for L. (L.) amazonensis
(A, C) or L. (V.) braziliensis isolates (B, D). The data are expressed as the mean ± SEM from 3 separate experiments for L. (V.) braziliensis and the mean ± SEM from 4 experiments for L. (L.) amazonensis. Parasites were used in stationary phase of growth. Statistical analysis was performed using the paired t-test.