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 f unctions 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 i mmune response (CMIR). Using the monoclonal antibody 5C6 as a pan NK phenot ype 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 th e control (unselected) pigs being higher (with respect to target cell bindi ng) 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 s ignificant negative correlation with antibody after secondary immunization with hen egg white lysozyme (HEWL). Therefore, simultaneous selection for a ntibody and CMIR altered the frequency and function of NK cells in pigs wit h C greater than or equal to H > L.