Induction of calcium flux and enhancement of cytolytic activity in natural killer cells by cross-linking of the sheep erythrocyte binding protein (CD2) and the Fc-receptor (CD16)

• Published in: The Journal of immunology (1950) Vol. 139; no. 6; pp. 1772 - 1779
• Main Authors: Anasetti, C, Martin, PJ, June, CH, Hellstrom, KE, Ledbetter, JA, Rabinovitch, PS, Morishita, Y, Hellstrom, I, Hansen, JA
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Assoc Immnol 15.09.1987; American Association of Immunologists
• Subjects: Antibodies, Monoclonal - immunology; Antigens, Differentiation, T-Lymphocyte; Antigens, Surface - immunology; Applied sciences; Calcium - physiology; Cell Line; Cytotoxicity, Immunologic; Exact sciences and technology; Humans; Immunity, Cellular; Immunity, Innate; Immunologic Capping; Killer Cells, Natural - physiology; Other techniques and industries; Receptors, Fc - immunology; Receptors, IgG
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.139.6.1772

Binding of the anti-cluster of differentiation (CD) 2 monoclonal antibody 9-1 causes an increase in the concentration of cytoplasmic-free calcium ([Ca2+]i) in cultured CD3-/CD16+ natural killer (NK) cells. This response did not occur in cultured CD3+/CD16- cytotoxic T lymphocytes (CTL). Anti-CD16 antibodies could partially block the calcium response when NK cells were stimulated with intact antibody 9-1, and antigen-binding fragment F(ab')2 of antibody 9-1 did not produce a calcium response. Thus an interaction of the 9-1 antibody with CD16 Fc receptors was required for the functional effect. The dual interaction of antibody 9-1 with both CD2 and CD16 was demonstrated by comodulation experiments. The cytolytic activity of cultured NK cells was increased by antibody 9-1 but not by F(ab')2 fragments of antibody 9-1. The enhanced lytic activity was blocked by anti-CD16 antibody, anti-CD18 antibody, and anti-CD2 antibodies that do not block the binding of antibody 9-1. This pattern was distinct from antibody-dependent cell-mediated cytotoxicity which was blocked only by the anti-CD16 antibody. Thus antibody 9-1 enhanced cytotoxicity by activating effector cells. There was no enhancement of lytic activity when F(ab')2 of antibody 9-1 were cross-linked with a polyclonal antiglobulin, even though [Ca2+]i was increased. These results show that induction of a [Ca2+]i response is not sufficient to enhance lytic activity in NK cells, and suggest that signals delivered through CD16 are necessary.