Figure 5
Role of heavy chain isotype in protection. Naive BALB/c mice were injected i.p. with 10 μg mAb 14C2 of G1 (triangles pointing down), G2b (diamonds) or G2a (triangles pointing up) isotype. The control group (open squares) received PBS i.p. One day later, mice were exposed to a total respiratory tract challenge with PR8 (4 LD50 in 50 μl) and monitored for weight loss. Pooled data from two independent experiments are shown, each performed with 4–5 mice/group. A. Symbols show mean % body weight and SEM (relative to day 0) of 9–10 mice/group. Differences between treatment groups were tested for statistical significance at individual days. Mice treated with G2a showed significantly (p < 0,05, ANOVA) less weight loss than those treated with G1 or G2b at days 6 to 13 p.i. B. Survival. Death was defined as >30% weight loss, at which stage mice were euthanized. Differences between survival curves were tested for statistical significance by log rank test.