Figure 2.

Resistance in Ii −/− mice represents control of parasite growth in tissues. Cohorts of C57BL/6 Ii −/− or Ii +/− mice, together with class II −/− and susceptible BALB/c mice, were infected with L. major and, after 8 wk, the popliteal lymph nodes and spleens were homogenized in equivalent volumes of media and serially diluted into growth media that supported the conversion of intracellular organisms to the extracellular promastigotes. Wells were examined 2 wk later for motile promastigotes using inverted microscopy.