KB cells for antinuclear antibody determination: comparison with HEp-2 cells and the Crithidia luciliae assay.

Fifty-seven sera from 53 patients were assayed simultaneously on KB and HEp-2 cells and compared with regard to pattern and titer. Additionally, KB cell fluorescent antinuclear antibody (FANA) titer and pattern in 310 sera from 194 patients were compared with regard to the presence of antinative DNA antibodies (anti-nDNA ab) as determined by the Crithidia luciliae assay. Sixty-five percent (37/57) of the sera had the same titer on both KB and HEp-2 cells; the remainder had higher titers using KB cells. Regression analysis yielded a highly significant, unbiased correlation between the substrates. Forty-four percent (25/57) of these sera gave identical patterns on both substrates, another 25 of the 57 sera (44%) gave different patterns on the two substrates and 12% (7/57) could not be compared because they were negative on HEp-2 cells. KB cells detected positive FANA in 30 of 30 (100%) diagnosed cases of systemic lupus erythematosus; HEp-2 cells detected 29/30 (97%). From the standpoint of sensitivity, these data indicate a slight advantage to the use of KB over HEp-2 cells. Seventeen percent (53/310) of the sera were positive for anti-nDNA ab. The highest percentage of these positive sera occurs at reciprocal FANA titers between 320 and 1280. No association was found between KB FANA patterns and a positive Crithidia luciliae assay.