The establishment of the plasma cell survival niche in the bone marrow.

Antibodies continuously secreted by plasma cells play a central role in humoral immune protection of the organism. These plasma cells are generated during the germinal center reaction, and it is likely that they here acquire the potential to develop into long-lived cells. To achieve longevity, these cells require factors provided by the microenvironment. Indeed, only a few of the plasmablasts arising during an immune response will differentiate into mature plasma cells, which may survive for decades in specialized survival niches in the bone marrow. Here, we discuss how the survival niche in the bone marrow is established and what is known about the cell-cell interactions needed to support the long-term survival of plasma cells. A particular emphasis is put on the role of eosinophils, which have been shown to be key providers of plasma cell survival factors. The data suggest that the reticulum of bone marrow stromal cells supports a dynamic survival niche, in which long-lived plasma cells are provided with essential factors by a continuously turning over population of eosinophils and other cells.