engleski

Determination of antigen and antibody concentrations by microgravimetry.

The methods widely used for the determination of antibody (Ab) and antigen (Ag) levels in body fluids are still based on Ab/Ag interactions. Since these methods require the use of standards, the Ab/Ag avidities of both standard and system to be analysed, must be identical. In practice, this condition is usually not fulfilled and the quantitation of Ab or Ag is, to a greater or lesser degree, inaccurate. In order to overcome this problem, a method, based on microgravimetric analysis of at least two Ab/Ag precipitates of different stoichiometric compositions,is proposed. The method enables simultaneous determination of both Ab and Ag concentrations. The Ab/Ag precipitates should be prepared at equivalence and allowed to reach the equilibrium state. The method is tested so that the concentrations of human serum albumin (HSA) are determined using rabbit antibodies of various avidities. The precipitations, carried out in buffers of various pHs, enable the preparation of the Ab/Ag precipitates of different stoichiometric compositions. Isolation, purification and labelling of immune components, as well as using of standards, are not required. The minimal precision of the method is ą0.2 microgram of protein. The coefficients of variations are 0.09 to 0.21% for Ag and 0.01 to 0.06% for Ab concentrations. The results obtained are independent of the avidity of the Ab/Ag system to be analysed.

antigen; antibody; immunoprecipitation; microgravimetry; concentrations

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