Specificity of human lymphocytes primed against allogeneic cells in vitro. 1. Optimalization of culture conditions for detection of HLA--D specificity.

The specificity of lymphocytes primed against allogeneic cells in vitro has been examined in order to find the optimal conditions for detection in the restimulating response of HLA--D specificity, as defined by homozygous cell typing. It was found that reducing the number of stimulating cells to less than the number of responding cells (ratio R/S = 4 : 1) in the priming culture, and increasing the number of stimulating cells at restimulation gave better discrimination. Priming with HLA--D heterozygous stimulating cells, where the responding and stimulating cells shared the other HLA--D determinant, rendered the primed cells somewhat more discriminatory than priming with HLA--D homozygous cells. The optimal length of the secondary culture was found to be about 38 h.