Expression of interferon-gamma receptors on bladder cancer cells: does it correlate with biological response?

Previously we have shown a differential biological response of three human bladder cancer cell lines (RT4, RT112 and MGH-U1) to gamma interferon (IFN-gamma). The present study examines the relationship between the biological response and the expression of the interferon-gamma receptor on the tumour cell surface. Using a competitive radioligand binding assay and Scatchard analysis, we measured the number and affinity of the IFN-gamma receptors on each of the above cell lines. Individual cells from each line expressed large numbers (29,100-41,800) of high-affinity receptors (kd = 2.4-3.9 x 10(10) M). There was no statistically significant difference in either of these parameters between the three lines. We therefore conclude that the biological response of these bladder lines to IFN-gamma does not relate to the number or affinity of its receptor on the plasma membrane of these tumour cells.