Protection and capsule reactivity of subclass switch families of mAbs F24F2 and F26G3.

<p>A – Protection afforded by passive immunization. Mice (n = 8–10 mice/group) were treated with the indicated dose of mAb and challenged 18 h later via the intratracheal route with 10 LD₅₀ of <i>B. anthracis</i> spores (Ames). Statistical comparison of survival of mAb-treated mice vs. control mice given DPBS alone was done with Fisher exact test; * <i>P</i><0.05. B – Capsule reaction produced by incubation of <i>B. anthracis</i> vegetative cells with mAbs of each subclass (75 µg/ml). Red arrow – outer rim produced on binding of IgG3 mAb; blue arrow – inner binding reaction of IgG3 near the cell wall.