Detection of Interleukin 1 with Human Dermal Fibroblasts

Abstract

A fibroblast proliferation assay was developed for the detection of interleukin 1 (IL 1).Proliferation was measured by thymidine incorporation and by staining of cellular proteins with crystal violet. Response of fibroblasts was optimal at cell numbers of 4,000 to 9,000 cells/ culture and an incubation period of four days. Serum content of the culture medium, ranging from 1 to 10 % fetal calf serum (FCS), enhanced the proliferative response in a concentrationdependent manner, while higher concentrations of FCS did not lead to further increase. Both detection methods were equally suitable for the measurement of IL 1 biological activity in purified and crude preparations. In contrast to the conventional thymocyte comitogenic assay, the fibroblasts in this assay did not proliferate in response to IL 2 or IL 6. Fibroblasts were weakly stimulated by recombinant (rec) tumor necrosis factor (rec TNF-α); they did, however, not proliferate in response to mitogens, lipopolysaccharide, rec granulocyte-macrophage colony stimulating factor (rec GM-CSF), macrophage-CSF, rec interferon-γ, insulin or transferrin. The detection of IL 1 activity by crystal violet staining of human dermal fibroblasts was easier and faster than by measurement of thymidine incorporation of fibroblasts or mouse thymocytes; without loss of sensitivity, the sample capacity of the IL 1 assay could be enhanced, and the use of experimental animals was avoided.