Lymphocyte transformation in patients with cobalt dermatitis

A lymhocyte transformation test with cobalt chloride was performed in 14 patients who had positive cobalt patch tests and eczema compatible with a cobalt induced contact dermatitis and in 9 controls. Eight of the patients had strongly positive patch tests, while 6 had weakly positive patch tests. Patients and controls showed equivalent responses to the mitogens, phytohaemagglutinin, pokeweed mitogen, and concanavalin A, as well as to the recall antigens, purified protein derivative and Candida albicans. A 1:5000 dilution in RPMI-1640 medium of a 1% aqueous solution of cobalt chloride proved optimal in distinguishing patients from controls. With this dilution, a significantly higher lymphocyte transformation was found in patients with strongly positive cobalt patch tests than in the controls. No significant difference was detected when the results for patients with weakly positive patch tests were compared with those of the controls.