964 ENHANCED LYMPHOKINE-ACTIVATED CELLULAR CYTOTOXICITY IN CORD MONONUCLEAR CELLS

Abstract

Various forms of cellular cytotoxicity have been noted by us and others to be decreased in newborn whole mononuclear cells (WMC) as compared with adult WMC. Diminished cord spontaneous natural killer (NK) cell activity against K562 targets has been observed. However, after incubation for 5–7 days with purified recombinant interleukin-2 (IL-2) cord WMC cytotoxicity against K562 cells increased from 16 ± 2% (SEM) to 74 ± 5% (n=9). Killing of Raji cells increased from 7 ± 1% to 38 ± 4% (n=9). Similarly activated adult WMC also increased their killing against K562 from 31 ± H% to 68 ± 7% and against Raji cells from 7 ± 1% to 40 ± 7% (n=10). Dose-dependent responses were observed with the optimal IL-2 concentration at 50–100 units/cc. Increased cytotoxicity was also observed against other cell targets (Molt 4F and EL-4). Cold target inhibition of Molt and Raji killing was equally inhibited in adult and cord lymphokine-activated killer cells (LAK) by K562, Molt or Raji cells. However, cold target inhibition of cord LAK activity against K562 was less than adult LAK, suggesting less specificity and more potent cytotoxic potential. Unlabelled K562 cells decreased cytotoxicity by 44 ± 5% for adult LAK (n=7) and 27 ± 9% for cord LAK (n=4). Unlabelled Raji cells decreased K562 cytotoxicity by 34% for adult cells and 12 ± 3% for cord cells (p<0.01). This substantial lymphokine-activated cytotoxicity suggests the possibiltiy of therapeutic intervention in neonatal viral infections and neoplastic disorders with purified lymphokines.