1011 DECREASED NATURAL AND ANTIBODY DEPENDENT CELLULAR CYTOTOXICITY IS ASSOCIATED WITH DECREASED PRODUCTION OF NATURAL KILLER CYTOTOXIC FACTORS AND INTERFERON IN NEONATES

Abstract

Cord blood lymphocytes (CBL) were compared with adult peripheral blood lymphocytes (aPBL) for their: 1) natural killer (NK) and antibody dependent cellular cytotoxic (ADCC) activities, 2) target binding capacity, 3) ability to induce soluble natural killer cytotoxio factor (NKCF), 4) interferon (IFNα) and interleukin 2 (IL2) induced augmentation of NK activity and 5) capacity to produce IFN against tumor targets in vitro. For the NK assay, K562 cells were used as targets whereas in the ADCC assay, antibody coated SB cells were used in a 4 hr 51Cr release assay. CBL depleted of adherent cells and Percoll separated NK enriched subpopulations demonstrated significantly lower NK and ADCC activities compared to aPBL. However the target binding ability of CBL was comparable to aPBL. CBL produced significantly lower levels of NKCF in response to K562 tumor targets compared with aPBL. Although the NK activity of CBL was not stilmulated by either IFN or IL2 to the same levels shown by aPBL, the percent enhancement of cytotoxicity of CBL by IFN and IL2 was greater than aPBL. The ability of CBL to produce IFN in vitro against K562 target cells was significantly lower than aPBL, Our results suggest that decreased NK and ADCC activities and NKCF production by CBL may be associated with diminished IFN production, thereoy predisposing neonates to an increased susceptibility to infection.