NEW MONOCLONAL ANTIBODIES TO THE PROSTATE-SPECIFIC ANTIGEN: OBTAINING AND STUDYING BIOLOGICAL PROPERTIES

Abstract

Original set of 15 clones of hybridomas producers of monoclonal antibodies (mAbs) to prostate-specific antigen (PSA) (using as a source of lymphocytes of mice of inbred strains NZB and Balb/c) was obtained. The activity in ELISA, affinity constant and titer in the culture fluid of the mAbs obtained from NZB mice are higher compared to the mAbs obtained from the Balb/c mice splenocytes. Conjugates of obtained mAbs with horseradish peroxidase were synthesized, and it allowed performing comparative epitope characterization of the resulting set of mAbs. Studied mAbs are directed to 4 epitopes of PSA molecule: 2 mAbs interacting with one of the epitopes showed cross-activity with PSA-related protein – human kallikrein 2; 2 mAbs of the same epitope specificity blocked the enzymatic activity of PSA; mAbs of the remaining two epitopes either did not affect PSA chymotrypsin activity at all, or this inhibitory effect was not significant. The obtained mAbs recognize antigenic determinants that are not screened when interacting with α1-antichymotrypsin, as well as those that are localized in the places where α1-antichymotrypsin interacts with PSA. Within each of the given two mAbs groups, there are antibodies belonging to different epitopes, which give prospects for the further use of the obtained mAbs in immunoassay and immunobiotechnology. Two alternative methods for determining of the mAbs constants of affinity (by Friguet and Scatchard) are comparable (for determination of the affinity constants of anti-PSA antibodies): coefficient of linear correlation between the affinity constants defined by different methods was 0.90.