GROWTH-HORMONE AND INSULIN-LIKE GROWTH-FACTOR-I AUGMENT ESCHERICHIA COLI-KILLING ACTIVITY OF MURINE PERITONEAL EXUDATIVE CELLS

Effects of growth hormone (GH) and insulin-like growth factor (IGF)-I on Escherichia coli-killing activity of murine peritoneal exudative ce lls (PECs) were investigated, Plasma from the mice, injected subcutane ously with saline, GH (4.8 mg/kg/day), or IGF-I (24 mg/kg/day) for 6 d ays, was mixed with E. coli and pooled murine PECs. Plasma from GH- an d IGF-l-treated mice modestly but significantly augmented the E. coli- killing activity of PECs, as compared with that from saline controls. Plasma from IGF-l-treated mice also enhanced PEC interleukin 1 product ion. In the next experiment, PECs preincubated with medium, GH (10-100 0 ng/ml), or IGF-I (50-5000 ng/ml) for 3 h were investigated for E. co il-killing activity. Preincubation of PECs with all concentrations of GH and IGF-I significantly enhanced the E. coil-killing activity of PE Cs, as compared with the medium control. These results indicate that G H and IGF-I enhance phagocytosis and the E. coli-killing activity of P ECs, via a modestly increased plasma capacity to support these activit ies, as well as by a strong direct action.