Description
IL21 stimulates proliferation of B-cell stimulated by crosslinking of the CD40 antigen. It inhibits proliferation stimulated by IL4 plus anti- IgM. IL21 augments stimulation of the proliferation of naive CD45RA (+) but not memory CD45R0 (+) T-cells mediated by engagement of CD3. IL21 stimulates the proliferation of bone marrow progenitor cells and the expression of the NK-cell marker CD56 in the presence of IL15. The Interleukin-21 receptor is closely related to human IL2 beta receptor. The receptor contains a WSXWS motif in the extracellular region, typical of type 1 cytokine receptors. The receptor is expressed on NK-cells, T- cells, and B-cell line.The functional signaling complex activates Janus kinases JAK1, JAK3, and the STAT proteins STAT1, and STAT3