g and incubated for four hours at 37 u00b0 c in a 5 5 co 2 atmosphere plates were centrifuged again and 100 ul aliquots of supernatant were collected and counted percentage of 51 cr release was calculated as follows equ1 where er is observed experimental 51 cr release sr is spontaneous release measured by incubating 10 3 labeled cells in 200 ul of medium alone and mr is maximum release obtained by adding 100 ul 0 3 triton x 100 to target cells those mononuclear blood samples which showed high ctl activity were expanded and cloned via limiting dilution and were screened again using the same methodology these experiments led to the isolation of several ctl clones from patient mz2 including ctl clone 34 81 12 34 the experiment was repeated as described using both cell line mz2 mel 3 0 and mz2 mel 3 1 the results indicated that clone 81 12 recognized both mz2 mel 43 and mz2 mel 3 0 but not mz2 mel 3 1 the antigen being recognized by 81 12 is referred to hereafter as 34 antigen bb 34 in view of prior work as summarized supra it was of interest to determine the hla class 1 profile for patient mz2 this was determined following standard methodologies which are now set.