Standardisation of the mixed lymphocyte reaction.

The mixed lymphocyte reaction has been optimised with Ficoll--Triosil separated lymphocytes: 100,000 responding cells with 100,000 mitomycin-C-blocked stimulating cells, in 0.2 ml of TC 199 with 10% AB-negative known normal serum in Cook microplates. After incubation at 37 degree C for 120 h, 2 muCi of [3H]thymidine was added, harvesting after a further 15 h at 37 degree C. A pool of stimulating cells, freshly separated from 5 normal subjects (usable up to 36 h if kept at 4 degree C), produced a Gaussian normal range of increment in CPM from 17,000--88,000, with a between-batch coefficient of variation for triplicates of 22%. For tests against stimulating cells from a single donor a transformation index above 1.64 was significant.