The effects of MHC and parasite clone on the course of disease symptoms. The mean parasitemia (log10-transformed) and the mean blood cell number (*109)/ml blood for MHC genotypes H-2ak (open triangles) and H-2bk (closed triangles), or pathogen clone AS (open diamonds) and clone CW (closed diamonds) are given over the course of the disease. Black symbols and lines refer to the data collected in this study on H-2ak and H-2bk mice, the green symbols and hatched lines refer to previously published results on homozygous H-2a and H-2b mice for comparison (Fig. 1 in . See Table 1 for statistics.