The in vitro assessment of various types of interferons for urological tumors by the human tumor clonogenic assay

The direct antitumor effects of various types of interferons (IFNs) were compared against urological malignancies, in particular the renal tumor using the human tumor clonogenic assay (HTCA). The concentrations of each IFN were 50 and 500 IU/ml, respectively, and the exposure time was continuous (2-4 weeks). IFN alpha A, beta, gamma, (recombinant type) and alpha (human lymphoblastoid type) were investigated in 37 specimens of urological primary tumors. Each tumor was judged to be sensitive to IFN by 70% colony inhibition when compared to the colonies of the controls. Eight (22%) of the 36 trials were sensitive to IFN. On the other hand, 3 cases (8%) were augmented cases defined as a colony increase of more than two times the standard error of control colony growth. The renal tumor had a tendency to be more sensitive to IFN than the other urological tumors (P less than 0.1). The order of the colony inhibition against the renal tumor was IFN gamma greater than alpha greater than alpha A, beta. This order was statistically significant (P less than 0.025, Wilcoxon's test). These results corresponded with the results reported by others. We recommend the HTCA as an adequate method for assessing the direct antitumor effect of IFN.