Antibodies and Measurement of Taxol in Serum Characterization of Polyclonal and Monoclonal Anti-Taxol

Anti-taxol antibodies were generated in the rabbit using a taxol-bovine serum albumin conjugate prepared from 2'-succinyltaxol using a mixed anhydride procedure. Immunization with 2'-succinyltaxol-bovine serum albumin gave rise to polyclonal anti-taxol antibodies. By a radioimmunoassay using [JH]taxol, a standard curve gave a 50% inhibitory concen tration of 1.0 MM. Taxol levels in human serum could be measured, with the lower limit of detection and measurement being 0.1 n\i or 0.085 ng/ml. Two mouse monoclonal anti-taxol antibodies were isolated by immu nizing ItM HA mice with the same antigen. One was an immunoglobulin G, (69E4A8E) and the other was immunoglobulin M (29B7B3C). The specificity of these antibodies was determined by a competitive enzymelinked immunosorbent assay with laxol and 10 different related deriva tives and analogues. 29B7B3C had higher binding affinities for biologi cally active derivatives and markedly lower affinities for inactive derivatives; i.e.. the specificity was consistent with the results of tubulin disassembly and cytotoxicity studies using the same taxol derivatives, making it suitable for screening for taxol or taxol-like compounds in extracts of natural products. 69E4A8E recognized the benzamidocarbamyl group at the C-3' position of taxol and had a lower affinity for other active compounds with different substitutions. Taxol levels in human se rum could be detected and measured by 69E4A8E using a competitive enzyme-linked immunosorbent assay. The lower limit of measurement was about 50 MMor approximately 42 ng/ml. Similar measurements could be made by radioimmunoassay.