Pep34, a synthetic peptide whose sequence corresponds to the intracytoplasmic domain of the epstein-barr virus receptor (CR2, CD21), regulates human B lymphocyte proliferation triggered through CR2.

CR2 is involved in regulation of human B lymphocyte proliferation by interacting, through distinct domains, with extracellular, cell surface or intracellular components. Contribution of CR2 intracytoplasmic domain in CR2 regulatory functions remains unclear. Thus, we used pep34, a 34 amino acid synthetic peptide whose sequence corresponds to CR2 intracytoplasmic domain. Pep34 was incorporated into B lymphocytes which were then activated by EBV or C3d through CR2. Our data demonstrate that pep34 inhibits 100 % B lymphocyte proliferation triggered by EBV or C3d. Irrelevant peptide had no effect. When B lymphocyte proliferation was triggered by a multipotent B cell activator as SAG, pep34 did not exert any inhibitory effect. Our data demonstrate that pep34 inhibits B lymphocyte proliferation only when lymphocytes are triggered through CR2. Thus, this strongly supports that despite its short length, CR2 intracytoplamic domain participates to regulatory functions of this receptor.