IL-4 production by T depleted cells from Nippostrongylus brasiliensis infected mice.

Interleukin-4 (IL-4) is known to be involved in both the in vivo IgE response and the elevated B cell IgE Fc receptor (Fc epsilon R11) expression seen after a parasite infection. To further analyze the relationship between Fc epsilon R11 expression and IL-4 production, purified B cells from uninfected, Nippostrongylus brasiliensis (Nbr) infected and from goat anti-mouse IgD (GaM delta) injected mice were isolated on various days post-treatment. The Fc episolon R11 levels on purified B cells from normal mice decreased after an overnight culture in media alone and addition of IL-4 to these cultures resulted in a 4 to 13-fold enhancement of Fc epsilon R11 levels. In contrast, the Fc epsilon R11 levels on B cells from Nbr infected mice were elevated after an overnight culture in media alone and addition of IL-4 did not further enhance the already upregulated Fc epsilon R11 levels. Overnight culture of purified B cell blasts from Nbr infected mice in the presence of an anti-IL-4 monoclonal antibody (11B11) caused the elevated Fc epsilon R11 levels to return to levels seen in normal mice, without affecting the Fc epsilon R11 levels on purified Go or B cell blasts from uninfected mice or Go B cells from Nbr infected mice. 11B11 also inhibited the elevated Fc epsilon R11 levels on highly purified B cells obtained by FACS sorting the non-adherent spleen cell population for class II+ cells. In contrast to Nbr infection, the Fc epsilon R11 levels on B cells were downregulated in the GaM delta injected mice. However, analogous to the Nbr system, the Fc epsilon R11 levels were unresponsive to the addition of exogenous IL-4. This study indicates that IL-4 production is seen in T depleted splenocytes and that this alternate source of IL-4 serves to maintain the elevated Fc epsilon R11 levels on B cells.