Natural killer (NK) activity and interferon (IFN) production by a fraction of spleen and blood lymphocytes in swine

Salmon, H.; Charley, B.; Labonnardiere, C.; Olivier, M.; Kelley, K.; Paraf, A.

After carbonyl iron treatment and gradient isolation, spleen and blood pig lymphocytes exhibited NK activity and produced IFN after viral induction. Removal of plastic-adherent cells, including the majority of B cells, did not change these activities. The plastic-non-adherent cells were further separated into two subsets of roughly similar size by panning using a monoclonal, anti-T, and anti-null cell antibodies (81+cells). NK activity and IFN production were found in the 81 − cell fraction. A significantly higher proportion of null lymphocytes from blood and of splenic Fc-gamma receptor-bearing lymphocytes was also found among the 81 − cell fraction as compared to the 81 + fraction, without any change among other subsets. Similar proportions of helper (PT4+), cytotoxic (PT8+) and total T cells (MSA4+) were found among lymphocytes bound to target K562 cells and among the whole lymphocyte population. In contrast, lymphocytes that bound K562 cells demonstrated a striking increase in the proportion of Fc-gamma receptor-positive cells of high affinity. These results show that NK cells and IFN-producing cells are mainly included in the same blood and spleen fraction, and suggest that among 81 − cells only those expressing an Fc-gamma receptor of high affinity are active.