Reduced ability of neonatal and early-life bone marrow stromal cells to support plasmablast survival.

In human infants (<1 year), circulating IgG Abs elicited in response to most T-dependent Ags rapidly decline and return to baseline within a few months after immunization for yet-unknown reasons. In mice immunized between 1 and 4 wk of age, a limited establishment of the bone marrow (BM) pool of long-lived plasma cells is observed. In this study, we show that tetanus toxoid (TT)-specific plasmablasts generated in the spleen are efficiently attracted in vitro and in vivo toward early-life BM stromal cells, which express adult levels of CXCL12.