Binding characteristics of radioiodinated crystal-induced chemotactic factor to human neutrophils.

TL;DRAbstract

The binding of radiolabeled crystal-induced chemotactic factor (CCF) to human neutrophils is characterized. Binding of 125I-CCF to the cells was higher at 4 degrees C than at 24 degrees or 37 degrees C and was found to be independent of CA2+ and Mg2+ ion concentration. The binding showed a pH optimum of 6.0. Tosylamido phenylethyl chloromethyl ketone at 100 mumol/L concentration inhibited 20% of 125I-CCF binding, but phenylmethylsulfonyl fluoride at 200 mumol/L had no effect. Approximately 50% of cell-associated 125I-CCF was released after treatment with proteases. The nonspecific uptake by the cells, as measured by the uptake of 3H-sucrose and 14C-inulin in the presence of CCF, was negligible. After the steady-state binding of 125I-CCF to the cells, approximately 15% of the cell-associated radioactivity at 4 degrees C and 40% to 50% at 24 degrees and 37 degrees C was released into the medium after 60 minutes of incubation in medium alone. Dissociation of the radioactive material was n

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