ASSOCIATION CONSTANTS OF MONOCLONAL-ANTIBODIES FOR HAPTEN - HETEROGENEITY OF FREQUENCY-DISTRIBUTION AND POSSIBLE RELATIONSHIP WITH HAPTEN MOLECULAR-WEIGHT

Using published data, we have investigated the relationship of the association constant (K-a) of 265 MAbs for haptens with molecular weights ranging from 111 to 1202 Da. The study indicates that: (1) differences of a factor 10(3)-10(5) are frequently found between the lowest and the highest value of K-a for the same hapten; (2) the relationship between log K-a and the hapten molecular weight of either the native drug or the molecular entity used for the K-a determination is described by a hyperbolic function; (3) beyond a critical molecular weight of approximately 300-325 Da, the log K-a reaches a plateau at a maximal value near 10(-12) M(-1)