Differential responsiveness of immature- and mature-stage murine B cells to anti-IgM reflects both FcR-dependent and -independent mechanisms

Lipopolysaccharide prevents apoptosis and induces responsiveness to antigen receptor cross‐linking in immature B cells

“…This result, which confirms our previous observations using partially purified cells, 23 contrasts with other reports suggesting that anti-immunoglobulin antibodies generate negative signals that inhibit the response to LPS. 28,29 The reasons for the discrepancy between these studies and our own remain unclear.…”

“…Preliminary studies indicated that pretreatment of immature B cells with anti-m had little effect on their responsiveness to LPS (R. Wechsler-Reya & J. G. Monroe, unpublished observations). 23 On the other hand, as shown here, pretreatment of these cells with LPS allowed them to mount a significant proliferative response to subsequent stimulation with anti-m. Induction of responsiveness to anti-m required exposure to LPS for at least 8 hr, and was not due to the mitogenic effects of LPS, since cells pretreated with LPS for 8 hr and then washed showed little increase in thymidine incorporation unless they were restimulated with anti-m.…”

T cell control of the gut IgA response against commensal bacteria

“…11 Neonates, including human infants, are essentially unresponsive to microbial polysaccharide Ags until up to about 18 months in the case of humans 16. This unresponsiveness is not predicted by the MacPherson/Zinkernagel hypothesis but is generally considered to reflect a mechanism of peripheral tolerisation operative in “virgin” T independent B cells 17. The anergy developing in these cells can be antagonised by or prematurely prevented by encounters of B cells with lipopolysaccharide 18.…”

Differential signaling via surface IgM is associated with VH gene mutational status and CD38 expression in chronic lymphocytic leukemia

“…We used goat IgG antibody because this binds poorly to human Fc receptors 17 and has been shown previously to behave similarly to F(abЈ) 2 fragments in CLL signaling assays. 13 For stimulation of CD79␣, we used the mouse monoclonal antibody (mAb) ZL7-4 16 and the supernatant boiled in sample buffer.…”