DETERMINATION OF KI-67 DEFINED GROWTH FRACTION BY MONOCLONAL-ANTIBODYMIB-1 IN FORMALIN-FIXED, PARAFFIN-EMBEDDED PROSTATIC-CANCER TISSUES

The applicability of MIB-1, a monoclonal antibody directed against the Ki-67 antigen, was studied in the PC-82 and LNCaP prostatic tumor mod els at various levels of proliferative activity. Statistically signifi cant correlations were found in LNCaP cultures between Ki-67 and MIB-1 scores (r = 0.84, P < 0.001), and in PC-82 tumors between MIB-1 score s and paraffin tissue Ki-67 (pKi-67) (r = 0.90, P < 0.001), frozen tis sue Ki-67 (fKi-67) (r = 0.86, P < 0.001), and BrdU uptake (r = 0.70, P < 0.001), respectively. pKi-67 scores were double the fKi-67 scores, which may be due to methodological differences. MIB-1 scores exceeded both the fKi-67 and pKi-67 scores. The affinity of MIB-1 for the antig en is much higher than the affinity of Ki-67, which may explain the di fferences. MIB-1 is a promising means of evaluating the presence of on ly minute amounts of the Ki-67 antigen in paraffin-embedded human tumo r material, especially in relatively slowly growing tumors. (C) 1995 W iley-Liss, Inc.