Mixed lymphocyte cultures using automated blood cell counters.

We compared the standard mixed lymphocyte culture technique with a new technique based on cell count and size distribution in a series of histocompatibility tests on 24 patients and 39 potential donors for bone marrow transplantation. We found that suspensions in which lymphocytes were undergoing transformation could be distinguished from those in which they were not after a 10-day incubation period by measuring the leucocyte count and size distribution in a Coulter S+ IV automated counter. The leucocyte count was higher and the size distribution was wider in suspensions where the lymphocytes were transforming. The correlation between relative response indices calculated using tritiated thymidine uptake or total nuclear mass was close (r = 0.7; p less than 0.001) although there were major differences in the response as assessed by each of the two techniques in some individual cases. We feel this method is suitable to screen large numbers of unrelated donors.