In vitro evaluation of porcine lymphocyte response to phytohaemagglutinin using a modified "whole blood" technique.

The purpose of these investigations was to develop a modified whole blood technique for measuring quantitatively the responsiveness of pig peripheral blood lymphocytes to phytohemagglutinin (PHA) in vitro. Washed blood cells from a fixed volume of blood were suspended in culture medium supplemented with foetal calf serum and stimulated with a pure mitogenic PHA preparation. The stimulation was measured by the incorporation of 3H-thymidine. Data are presented to show the effect of different variables on the culture system. The transformation response was measured at different levels of PHA and the reproducibility of the different responses from repeated investigations was used to evaluate the usefulness of the test. The best reproducibilities of the stimulation response were found at the high PHA concentrations. Also the calculated PHA concentration giving maximum stimulation response had a relatively high reproducibility and indicates that this value is a convenient and reliable alternative measure of the functional capacity of the lymphocytes.