Direct and indirect nickel-specific stimulation of T lymphocytes from patients with allergic contact dermatitis to nickel.

Fourteen T lymphocyte clones (TLC) specific for the contact allergen nickel were prepared either from lesional tissue biopsies or from peripheral blood of patients with allergic nickel-contact dermatitis. Two nickel-specific TLC, obtained from lesional tissue, responded to nickel without the participation of antigen-presenting cells (APC). This direct stimulation by nickel was not restricted by major histocompatibility complex-encoded molecules, since antibodies against HLA class I and II molecules did not block nickel-specific proliferation. Proliferation of other nickel-specific TLC was dependent on the presence of APC and was diversely restricted by HLA class II molecules. With one exception, the restriction determinants were present on HLA-DR and HLA-DQ molecules. Four TLC recognized nickel in association with subtypes of these serologically defined molecules. Five TLC seemed to recognize nickel in the context of highly unusual restriction determinants, since their restrictions could not be explained by the function of single polymorphic HLA class II epitopes. The absence of HLA class II restrictions and the occurrence of deviant HLA class II restrictions in part of the nickel-specific TLC are suggested to result from direct interactions of nickel with critical immune response molecules.