The comparison between normal and Epstein-Barr virus-transformed homozygous typing cells and their use for MLC, PLT and serological detection of human Ia-type alloantigens.

Normal human lymphocytes isolated from freshly drawn blood were repeatedly stimulated (up to five times) in mixed lymphocyte cultures (MLC) with five different Epstein-Barr virus (EBV)-transformed homozygous typing cells (HTC-LCL). Each time, the same WDW-specificity was used for the restimulation. The first and the second stimulations resulted in an 2.4- to 3.1-fold increase of the original responder cell number. But after the third, fourth and fifth stimulation decreasing amounts of specifically primed lymphocytes were recovered. Primed lymphocyte typing (PLT) showed significant differences in the intensity of the stimulation depending on whether homozygous typing cells (HTC) or HTC-LCL were used as stimulators. Except for one cell type, the PLT-response was significantly stronger with HTC-LCL than with HTC. The time needed to reach the maximal PLT-response got shorter and shorter the more often the cells were reprimed by the same stimulator cell. Further differences between HTC and HTC-LCL were observed in the complement-dependent cytotoxicity assay: HTC-LCL were more sensitive towards rabbit complement and they showed an enhanced binding of anti-Ia-alloantibodies but HTC reacted more specifically with the antibodies.