The aim of the study was to develop methodological approaches for the production of heterogeneous antigens common to humans, animals (guinea pig) and microorganisms (pathogens of plague and brucellosis), and antibodies to them using magnetic affinity sorbents. Materials and methods: isolation of tissue (parenchymal organs) and bacterial water-soluble antigens, preparation of immune rabbit sera, creation of antigenic and antibody affinity sorbents, creation of immunofluorescence and immunoenzyme antigens for control reactions, purification of antigens and antibodies using magnoimmunosorption methods, developed by us. Results and conclusion. Mimicry antigens common in humans and guinea pig with pathogens of plague and brucellosis and antibodies to them were determined and isolated. The control immunochemical reactions at the stage of isolation of purified tissue heterogeneous antigens, the test samples exceeded the control by 2–3 times using immunosorbents prepared from commercial brucellosis and plague antisera, and by 3–5 times – from experimental brucellosis antisera.