ACTH adrenal cell bioassay: Improved sensitivity (12 ng/L) achieved by immunoextraction of ACTH from human plasma by a monoclonal antibody

R. Mitchell, A. Lambert, S. R. Crosby, A. White, W. R. Robertson

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We have previously reported a bioassay for human plasma ACTH based upon trypsin dispersed guinea-pig adrenal cells which was sensitive to 100 ng/L ACTH in unextracted human plasma when measured against human pituitary ACTH (1-39) standard 74/555. We now present a bioassay of increased sensitivity (12 ng/L) which incorporates three major changes. The trypsin/trypsin inhibitor step in the cell dispersion protocol has been replaced with collagenase, donor calf serum (3%) has been incorporated into the standard curve and ACTH has been extracted from human plasma and dilutions of standard hormone by a sephacryl bound monoclonal antibody (2A3) directed towards the 25-39 sequence. The extracted standard curve has a detection limit of 6 ng/L and the cells can tolerate up to 50% plasma equivalent concentration. Thus, the improved assay has a detection limit of 12 ng/L ACTH in plasma. The assay can now measure bioactive plasma ACTH levels reliably in the normal range.
    Original languageEnglish
    Pages (from-to)59-64
    Number of pages5
    JournalAnnals of Clinical Biochemistry
    Volume27
    Issue number1
    Publication statusPublished - 1990

    Keywords

    • collagenase
    • Trypsin

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