Human recombinant interleukin-2 augments porcine natural killer cell cytotoxicity in vivo

Immunological parameters of porcine peripheral blood mononuclear cells after in vivo injections of human recombinant interleukin-2(125) (HrIL-2) were studied. Eighteen pigs (6 pigs/group) were injected with either 10(4) or 10(5) units/kg body weight of human rIL-2 or an equivalent volume of sterile physiological saline (control) on days 0 through 4. All pigs were immunized with an E coli J5 bacterin on day 0. Cytolytic activity to porcine fibroblasts (PK-15) was increased (P less than 0.02) in pigs treated with HrIL-2 when compared to control animals. Cytotoxicity to K-562 cells also showed a tendency (P less than 0.08) towards increased cytolytic activity in the HrIL-2-treated pigs. Lymphocyte blastogenesis, IL-2 production, and serum iron concentrations did not differ between treatment groups. Antibody concentrations to E coli J5 antigens increased significantly (P less than 0.05) in all groups after immunization, but there were no differences between treatment groups. These data suggest that in vivo injections of Hr-IL-2 increase natural cytotoxic cell activity in pigs without influencing other immune activities.