CS1, a novel member of the CD2 family, is homophilic and regulates NK cell function

Pappanaicken R. Kumaresan, Wayne C. Lai, Samuel S. Chuang, Michael Bennett, Porunelloor A. Mathew

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107 Scopus citations


CS1 is a novel member of the CD2 subset of immunoglobulin superfamily (IgSF) expressed on NK, T and stimulated B cells. The cytoplasmic domain of CS1 contains immunoreceptor tyrosine-based switch motif (ITSM) which is present in 2B4, SLAM and CD84. The signaling adaptor molecule SAP/SH2D1A, the defective gene in X-linked lymphoproliferative disease (XLPD), binds to ITSM and regulates immune cell function. However, recent studies indicate that CS1 may be regulated by a SAP-independent mechanism. In this study, we have examined the ligand specificity of CS1 and the effect of CS1 interaction with its ligand on the cytolytic activity of YT, a human NK cell line. Recombinant fusion protein, CS1-Ig, containing the CS1 extracellular domain and Fc portion of the human IgG bound cells transfected with CS1. CS1-Ig did not show any binding to cells expressing other members of the CD2 family. The cytolytic activity of YT was enhanced in presence of soluble CS1-Ig fusion protein. These results demonstrate that CS1 is a self-ligand and homophilic interaction of CS1 regulates NK cell cytolytic activity.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalMolecular Immunology
Issue number1-2
StatePublished - 15 Sep 2002


  • CD2 subfamily
  • Cytotoxicity
  • Homophilic interactions
  • NK cells


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