title: CS1 (CRACC, CD319) induces proliferation and autocrine cytokine expression on human B lymphocytes.
abstract: CS1 (CRACC, CD319), a member of the CD2 family of cell surface receptors, is implicated in the activation of NK cell-mediated cytotoxicity. Previous studies showed that CS1 is also expressed on activated B cells. However, the functional role of CS1 in human B-lymphocytes is not known. Two isoforms of CS1, CS1-L and CS1-S, are expressed in human NK cells that differentially regulate NK cell function. CS1-L contains immunoreceptor tyrosine-based switch motifs in its cytoplasmic domain whereas CS1-S lacks immunoreceptor tyrosine-based switch motifs. In this study, we show that human B lymphocytes express only the CS1-L isoform, and its expression is up-regulated upon B cell activation with various stimulators. Moreover, anti-CS1 mAb strongly enhanced proliferation of both freshly isolated as well as activated B cells. The enhanced proliferation effects of CS1 were most prominent on B cells activated by anti-CD40 mAbs and/or hrIL-4. The effects of CS1 on B cell proliferation were shown on both naive and memory B cells. Human cytokine microarray and quantitative real-time PCR results indicated that CS1 activation enhanced mRNA transcripts of flt3 ligand, lymphotoxin A, TNF, and IL-14. Neutralizing Abs against lymphotoxin A, TNF-alpha, and/or flt3 ligand abolished the ability of CS1 on the B cell proliferation. These results suggest that activation of B lymphocytes, through surface CS1, may be mediated through secretion of autocrine cytokines and CS1 may play a role in the regulation of B lymphocyte proliferation during immune responses.
authors: Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.
authors: Jae Kyung
authors: JK
authors: Lee
authors: Stephen O
authors: SO
authors: Mathew
authors: Swapnil V
authors: SV
authors: Vaidya
authors: Pappanaicken R
authors: PR
authors: Kumaresan
authors: Porunelloor A
authors: PA
authors: Mathew
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D019898:Autocrine Communication / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D049109:Cell Proliferation; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D007113:Immunity, Innate; D007136:Immunoglobulins / Q000096:biosynthesis / Q000276:immunology; D007156:Immunologic Memory; D008213:Lymphocyte Activation; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D000071176:Signaling Lymphocytic Activation Molecule Family; D015854:Up-Regulation
chemical_list: D000911:Antibodies, Monoclonal; D016207:Cytokines; D007136:Immunoglobulins; D020033:Protein Isoforms; D011971:Receptors, Immunologic; C448987:SLAMF7 protein, human; D000071176:Signaling Lymphocytic Activation Molecule Family