Natural killer like – T cells regulate induction of short- and long- lived plasma cells (134.12)

Abstract

Abstract Sustained serum antibody (Ab) titers are in large part maintained by bone marrow-resident long-lived plasma cells (LLPC). Although several factors governing the survival of LLPC have been identified, the mechanisms by which LLPC are induced are not fully understood. We observed that natural killer like - T (NKT) cells made substantial contributions to vaccination-induced antigen-specific Ab responses. The Ab titers were sustained and correlated with the persistence of PC in the bone marrow. In CD1d-/- mice lacking NKT cells, the PC numbers were diminished but persistent, indicating a role for NKT cells in PC induction rather than survival. We therefore used an in vivo-labeling approach with 5-bromo-2-deoxyuridine, a nucleoside analogue that labels dividing cells. In conjunction with a flow cytometric analysis of bone marrow PC we observed that CD1d-/- mice had a reduced induction of CD138+/B220lo/CD44+ precursor cells as well as BrDU+/CD138+ short-lived PC (SLPC) and BrDU-/CD138+ LLPC. Our data show that NKT cells act at a stage of induction prior to the emergence of SLPC and LLPC. Efforts are underway in our laboratory to understand how NKT cells achieve their effects on PC induction. This work was supported by NIH Grant 5P20RR015564-07 from the National Center for Research Resources.