Immunization induces activation of bone marrow eosinophils required for plasma cell survival.
, Berek C
Deutsches Rheuma Forschungszentrum, Berlin Ein Institut der Leibniz Gemeinschaft.
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Eosinophils have multiple functions as effector cells of the innate immune system but also as modulators of immune responses. As producers of cytokines required for plasma cell survival, they are essential for the long-term maintenance of plasma cells in the bone marrow (BM). Here we show that activation of eosinophils both in vitro and in vivo enhances expression of the plasma cell survival factors APRIL, IL-6, IL-4, IL-10 and TNF-α. The in vivo activation of eosinophils is independent of the type of adjuvant used for primary immunization. Although eosinophils are activated by adjuvant itself, a stable activation and a constant increase in BM eosinophils is observed only in the presence of antigen. Thus, the numbers and the quality of eosinophils are dependent on priming the adaptive immune system. With secondary immunization and re-activation of antigen dependent memory cells, the ability of eosinophils to promote plasma cell survival is further increased. These findings suggest that in T cell-dependent immune responses eosinophils are conditioned so as to support the long-term survival of plasma cells in the BM. It implies that through accelerated numbers of eosinophils stable plasma cell survival niches are established and the long term survival of plasma cells is ensured.
PMID: 22057654 [PubMed - as supplied by publisher]