Lipopolysaccharide Stimulates the Proliferation of Human CD56 super(+) CD3 super(-) NK Cells: A Regulatory Role of Monocytes and IL-10

• Published in: The Journal of immunology (1950) Vol. 165; no. 1; pp. 139 - 147
• Main Authors: Goodier, M R, Londei, M
• Format: Journal Article
• Language: English
• Published: 01.07.2000
• Subjects: CD56 antigen; killer cell inhibitory receptors
• ISSN: 0022-1767

NK cells recognize and kill tumor cells and normal cells, and these play an important role in immune defense in cancer, infectious disease, and autoimmunity. NK killing is regulated by positive or negative signals derived from the interaction of surface receptors with ligands on the target cells. However, the mechanisms controlling the proliferation and maintenance of NK cells in normal human individuals are less clearly defined. In this study, using an entirely autologous system, we demonstrate that human peripheral blood CD3 super(-) CD56 super(+), killer cell-inhibitory receptor (KIR)-expressing cells proliferate and expand in response to LPS. These responses are enhanced in the presence of anti-IL-10 receptor-blocking Abs or on the removal of CD14 super(+) cells from the cultures. This enhancement is also reflected in substantial increases in cytolytic activity and IFN- gamma production. The negative effect of CD14 super(+) cells may also be IL-10 mediated, IL-10 being lost from the culture supernatants of CD14-depleted PBMC and rIL-10 reversing the effect of this depletion. On the other hand, mRNA for the p35 and p40 subunits of IL-12 is still induced in CD14-depleted cultures. The expansion of CD3 super(-) CD56 super(+) cells was also inhibited by CTLA4-Ig, indicating a role for CD80/86. B lymphocytes were not required for the expansion of CD3 super(-) CD56 super(+) cells, whereas removal of MHC class II super(+) cells from CD14-depleted cultures resulted in a complete abrogation of these responses. Expansion of CD3 super(-) CD56 super(+) cells was reconstituted in MHC class II-depleted cell cultures by adding back monocyte-derived dendritic cells. These results indicate that the responses of CD3 super(-) CD56 super(+) NK cells to LPS may be driven by a MHC class II super(+) B7 super(+) CD14 super(-) peripheral population, most likely blood dendritic cells.