Different mice inbred strains humoral immune response against human prostate-specific antigen

The aim of the study was an investigation of humoral immune response to prostate-specific antigen (PSA) of different mice inbred strains for further development of recommendations for appropriate immunization schemes for monoclonal antibodies (McAbs) obtaining. The study was conducted using: Balb/c and NZB mice; PSA from human sperm (as immunogen). In case of booster immunization immunogen was previously diluted to the desired concentration (10 or 30 µg per 100 µl) in saline, and injected in the tail vein or intraperitoneally. In case of other immunizations, we prepared emulsion solution of immunogen with adjuvant to final concentration of 10 or 30 µg per 100 µl: PSA was dissolved in saline, the same volume of adjuvant was added, and mixture was thoroughly mixed to form a stable emulsion. When subcutaneous administration, total dose of 100 µl was divided into two equal parts and injected in the hind paw of mice. Intraperitoneal immunization was performed by single administration of 100 µl of emulsion. The level of specific antibodies was determined by titration of blood sera from animals in indirect ELISA. Series of experiments were conducted to determine the level of humoral response of mice of different inbred strains (Balb/c and NZB) for multi-stage immunization with different duration with different amounts of PSA (10 and 30 μg), with different immunoglobulin administration (intraperitoneal and subcutaneously), and with different adjuvants (Freund’s complete and incomplete adjuvants, FCA/FIA). Final booster immunization at a dose of 30 μg was performed either in the same manner as the previous administration of the immunogen, or intravenously in the physio­logical saline solution. Dependencies of the humoral immune response of Balb/c and NZB mice against PSA on the route of administration of immunogen, the dose and duration of immunization were established. It was shown that intraperitoneal administration provided formation of higher titers of specific antibodies in case of both mice strains. Balb/c mice lines more rapidly responded to PSA, than an NZB mice (for all investigated schemes immunization). It was shown that the most effective immunization scheme was three times intraperitoneal administration with 10 µg of PSA for 8 weeks (the first immunization with FCA, and the rest – with FIA) and booster immunogen intravenous administration in saline solution.