FIELD: medicine, medicinal immunology. SUBSTANCE: invention relates to the field of preparing highly purified and highly active protein preparations of the immune system of body that can be used in medicine and biochemistry for development of test-systems and for research aims. Method involves precipitation of blood serum euglobulins by dialysis against distilled water followed by dialysis of dissolved precipitate of euglobulin fraction against solution at pH 8.6-9.0 containing 1 mM of ε-aminocaproic acid and 0.01 M of EDTA. After removal of precipitated impurities supernatant is saturated with Na2SO4, formed precipitate is dissolved in solution at pH 6 containing 11% of Na2SO4, 0.005 M of Na2HPO4 and 0.01 M of EDTA and C3 component of complement is precipitated from the formed solution by dialysis against distilled water. Method provides preparing the complement of C3 component at the yield 60%. Obtained preparation has a single precipitation band with antiserum to all human serum proteins and has no impurities by immunoelectrophoresis and electrophoresis in polyacrylamide gel data. EFFECT: simplified method, high purity of preparation, absence of impurities, increased yield. 1 ex
