Lymphocyte transformation with cobalt in hard metal asthma

Lymphocyte transformation tests with cobalt were done in 9 hard metal asthma patients diagnosed on the basis of a positive bronchial provocation test with cobalt. Positive lymphocyte proliferation in response to the metal was defined statistically from the results of 18 controls comprising 12 hard metal-exposed and 6 non-exposed controls. Out of the 4 patients who had been reported to have IgE antibody specific to cobalt, the lymphocytes of 2 proliferated with metal: one showed positive lymphocyte transformation to free cobalt, the other to both free cobalt and cobalt-conjugated human serum albumin. These results suggest that cobalt-sensitized lymphocytes play a role in some hard metal asthmatics. However, the mechanism underlying the hard metal asthma in the other 5 asthmatics who had neither cobalt-specific IgE antibody nor cobalt-sensitized lymphocytes remain to be elucidated.