In the present study, we performed a detailed analysis of the B cell response to infection and found that although total numbers of B cells were expanded to similar extents in susceptible and resistant mice, the outcome of these expansions were different in terms of production of total and specific IgG ASC, activation status by CD69, CD86, Fas/FasL expression, and B cell subset expansion (Fig 5–, 7). This evidence concerns the gene CD86 and infection.