Automated reading of the microcytotoxicity test

From studies of 16,993 reactions in the microlymphocyte cytotoxicity test, we concluded that automatic fluorescent readings are comparable to those produced by visual readings with eosin dye exclusion. The r values (counting only strong reactions as positive) were as follows: 0.94 fluorescence machine versus visual fluorescence reading; 0.96 eosin visual reading, reader 1 versus reader 1; 0.97 eosin visual reading, reader 2 versus reader 2; 0.91 eosin visual reading, reader 1 versus reader 2; 0.98 fluorescence machine 1 versus machine 1; 0.98 fluorescence machine 2 versus machine 2; 0.96 fluorescence machine 1 versus machine 2; 0.92 fluorescence machine versus eosin visual reading; It was further shown that there was 93% concordance in assignment of HLA specificities between machine-assigned specificities and assigned by an experienced technologist. Most of the extra reactions obtained by fluorescence were in the crossreactive groups. Thus, the extra positive reactions obtained by the machine were likely to be the result of greater sensitivity than detection of random extraneous reactions.