The production of high affinity monoclonal antibodies to progesterone.

Using different immunisation regimens and the antigens 6 beta-hydroxyprogesterone hemisuccinate and 11 alpha-hydroxyprogesterone hemisuccinate conjugated to bovine serum albumin, we have produced 35 monoclonal antibodies against progesterone with a wide range of specificities and affinities (Ka = 8 x 10(7)-3 x 10(10) M-1). The 10 antibodies raised against the 6 beta-antigen showed no advantage in terms of specificity when compared with those raised against the 11 alpha-antigen. The four antibodies with the best binding characteristics were all derived from fusion experiments performed after long (5 booster injections) immunisation with the 11 alpha-antigen. Although the specificities of these monoclonal antibodies were similar to those of a high affinity rabbit antiserum raised against the same antigen, a measurable improvement in sensitivity was obtained when one of these four antibodies was used for radioimmunoassay.