Investigation of ability of the metal allergens cobalt chloride, nickel sulfate and potassium dichromate to give a mitogenic response in human thymocytes.

The metal allergens cobalt chloride, nickel sulfate and potassium dichromate were tested for the ability to give a mitogenic response in human thymocytes, both unseparated and Percoll-separated, including a fraction of low density, which has been shown to have characteristics of medullary cells (unsensitized, virgin T cells). With cobalt chloride and potassium dichromate, no stimulation occurred; instead, cobalt chloride at a concentration of 3.5 X 10(-5) M and potassium dichromate at 5.7 X 10(-7) M were inhibiting. After nickel sulfate addition, a small DNA synthesis stimulation was obtained in both unseparated cells and in fractionated cells of different densities. The results thus speak against that cobalt chloride and potassium dichromate are unspecific mitogens for human lymphoid cells, while an unspecific mitogenic effect is indicated for nickel sulfate.