Fig. 5

Ratios of the indicated IgG-subclasses in surviving C57BL/6 (a) and BALB/c (b) mice and antigen-specific IgG2c titers in respective C57BL/6 (c). Seven infected BALB/c and 8 C57BL/6 mice with a distinct antibody answer to R. pneumotropicus antigen (Fig. 4) were chosen for the determination of IgG subclasses in (a) and (b), respectively. In BALB/c mice the ratios between IgG2a to IgG1 and IgG2b to IgG1 were determined. As C57BL/6 mice lack IgG2a, only IgG1 and IgG2b were measured. Medians are marked by the horizontal line. Differentiation of a Th1 and Th2 immune response is indicated by the dashed line. IgG2c-titers in C57BL/6 mice against whole cell extract of R. pneumotropicus (c). Titers were determined as indicated either in experimentally infected survivors or respective controls (fbl = final bleeding). A serum pool from C57BL/6 mice naturally infected with R. pneumotropicus was used as reference serum. The non-parametric Mann-Whitney test was used for statistical analysis. The P-values are indicated