Functional versus quantitative comparison of IL‐1β from monocytes/macrophages on biomedical polymers

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Abstract
Studies utilizing a quantitative assay, radioimmunossay, and a biological activity assay, the murine thymocyte proliferation assay, to analyze IL‐1β cytokine production by monocytes/macrophages on biomedical polymers have been carried out. Results indicate that the quantitative analysis of IL‐1β on biomedical polymers and protein‐adsorbed biomedical polymers is not indicative of and does not correlate with the results of the biological activity assay. IL‐1β secreted from human monocytes/macrophages on Biomer, polydimethylsiloxane (PDMS), Dacron, polyethylene, expanded polytetrafluoroethylene, and control polystyrene with and without the preadsorption of physiological concentrations of human IgG, fibrinogen, and/or fibronectin was assayed. Quantitative levels of IL‐1β suggest a greater functional response than that observed in the biological thymocyte proliferation assay when the polymers were studied directly or preadsorbed with IgG. On the other hand, preadsorption with fibrinogen or fibronectin resulted in high functional activity for IL‐1β with low quantitative levels of IL‐1β. The lack of correlation between the functional and biological activity assays suggests the presence of other cytokines or antagonists which modulate the biological activity of IL‐1β. © 1993 John Wiley & Sons, Inc.