The Importance of Equilibrium Constant and Heterogeneity Index on Anti‐Rho(D) Quantitation Using the Auto‐Analyser¹

Thermodynamic and kinetic considerations, based on a standard bromelin/methylcellulose method for anti‐Rh o (D) quantitation using the Auto‐Analyser, have shown that the proportion of antibody bound at equilibrium and its rate of attainment is dependent on the mean equilibrium constant and heterogeneity index of the particular antibody preparation. Also, upon dispersal of the deliberately induced rouleaux, a new state of equilibrium is defined, the rate of attainment of which is related to the equilibrium constant. The principle of anti‐Rh o (D) quantitation using the Auto‐Analyser depends on individual antisera behaving in an identical manner to that of the standard preparation against which they are assayed. Evidence is presented in this paper that this premise cannot be substantiated unless the test and standard antisera have the same equilibrium constant and heterogeneity index.