Fig 6.

F₁ hybrid crossetween a silver-resistant (H-2^f) and -susceptible (H-2^s) genotype are resistant to silver, but not to mercury. Groups of F₁ hybrid crosses between silver-susceptible, A.SW (H-2^s) and its H-2 congenic silver-resistant A.CA (H-2^f) mice [(A.SW × A.CA) F₁ and/or (A.CA × A.SW) F₁ hybrids] were treated continuously with mercury (filled circles), silver (filled squares) or as controls, with saline (open squares) for 4 weeks. Thereafter, the mice were bled and killed. The sera were tested for the presence of IgG1 (a) and IgG2a (b) ANolA by using an indirect immunofluorescence (IIF) method. Hep-2 cell line was used as the substrate. Data are shown as mean + 1 s.e. Significant differences between the parameters in mercury-, silver- and saline-injected mice were calculated by Wilcoxon–Mann–Whitney test. **P < 0·01. n.s.: Not significant.