Cutting Edge: BAFF Regulates CD21/35 and CD23 Expression Independent of Its B Cell Survival Function

• Published in: The Journal of immunology (1950) 2004-01, Vol.172 (2), p.762-766
• Main Authors: Gorelik, Leonid, Cutler, Anne H, Thill, Greg, Miklasz, Steven D, Shea, Dianna E, Ambrose, Christine, Bixler, Sarah A, Su, Lihe, Scott, Martin L, Kalled, Susan L
• Format: Article
• Language: English
• Subjects: Animals; B-Cell Activating Factor; B-Cell Activation Factor Receptor; B-Lymphocyte Subsets - cytology; B-Lymphocyte Subsets - immunology; B-Lymphocyte Subsets - metabolism; Cell Differentiation - genetics; Cell Differentiation - immunology; Cell Survival - genetics; Cell Survival - immunology; Cells, Cultured; Female; Humans; Immunoglobulin D - biosynthesis; Immunoglobulin M - biosynthesis; Membrane Proteins - antagonists & inhibitors; Membrane Proteins - biosynthesis; Membrane Proteins - deficiency; Membrane Proteins - genetics; Membrane Proteins - physiology; Mice; Mice, Inbred BALB C; Mice, Knockout; Mice, Transgenic; Receptors, Complement 3b - biosynthesis; Receptors, Complement 3d - biosynthesis; Receptors, IgE - biosynthesis; Receptors, Tumor Necrosis Factor - biosynthesis; Spleen - cytology; Spleen - immunology; Spleen - metabolism; Tumor Necrosis Factor-alpha - antagonists & inhibitors; Tumor Necrosis Factor-alpha - deficiency; Tumor Necrosis Factor-alpha - genetics; Tumor Necrosis Factor-alpha - physiology; Up-Regulation - genetics; Up-Regulation - immunology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.172.2.762

Herein we demonstrate that B cell-activating factor of the TNF family (BAFF), a B cell survival factor, also regulates CD21/35 and CD23 expression. BAFF blockade in wild-type mice down-modulates CD21/35 and CD23 on B cells while survival remains intact, and BAFF exposure causes elevated CD21/35 and CD23 expression. Similar down-modulation is observed in bcl-2-transgenic mice treated with a BAFF inhibitor. This is the first evidence that BAFF has a function independent of B cell survival. Reports using CD21/35 and CD23 expression to assess splenic B cell subsets in BAFF-null mice concluded a lack of B cells beyond the immature stage. Since CD21/35 and CD23 are inadequate for delineating B cell subpopulations in BAFF-null mice, we used expression of BAFF-R and several B cell markers to identify more mature splenic B cells in these mice. These data broaden our understanding of BAFF function and correct the view that BAFF-null mice lack mature B cells.