Cutting Edge: Egress of Newly Generated Plasma Cells from Peripheral Lymph Nodes Depends on β2 Integrin

Abstract

During humoral immune responses, naive B cells differentiate into Ab-secreting plasma cells within secondary lymphoid organs. Differentiating plasma cells egress from their sites of generation and redistribute to other tissues, predominantly the bone marrow and mucosal tissues. In this study, we demonstrate that within peripheral lymph nodes newly generated plasma cells localize to medullary cords which express the β2 integrin ligand ICAM-1. In β2 integrin-deficient mice plasma cells accumulate inside the lymph nodes, resulting in severely reduced plasma cell numbers in the bone marrow. Since plasma cells isolated from β2 integrin-deficient animals migrate efficiently into the bone marrow when transferred i.v., our findings provide profound evidence that β2 integrins are required for the egress of plasma cells from peripheral lymph nodes.