Natural killer cell frequency and function in Yorkshire pigs selectively bred for high or low antibody and cell-mediated immune response.

Porcine NK cells are small to medium-size lymphocytes having a variety of functions that may include the regulation of immune response. Thus frequency and function of NK cells were examined in generations 6 and 8 (G6, G8) of pigs selectively bred for high (H) and low (L) antibody and cell-mediated immune response (CMIR). Using the monoclonal antibody 5C6 as a pan NK phenotype marker and target cell binding and lysis as assays of function, it was found that H and L immune response pigs had high and low NK cell frequency, respectively, at G6 and G8. Function of NK cells differed by line, with the control (unselected) pigs being higher (with respect to target cell binding) or similar (with respect to lytic activity) to H which were higher than the L line pigs. Frequency of NK cells after primary immunization was in significant negative correlation with antibody after secondary immunization with hen egg white lysozyme (HEWL). Therefore, simultaneous selection for antibody and CMIR altered the frequency and function of NK cells in pigs with C > or = H > L.