Production and characterization of monoclonal antibodies against two haptenic derivatives of 1 alpha,25-dihydroxyvitamin D3 conjugated with bovine serum albumin through the C-3 or C-24 position

Monoclonal anti-idiotype antibodies recognizing the variable region of a high-affinity antibody against 11-deoxycortisol. Production, characterization and application to a sensitive noncompetitive immunoassay

Anti-idiotype antibodies recognizing the variable regions of a particular anti-hapten antibody are valuable tools, which can be used in sensitive hapten immunoassays based on a noncompetitive format. Here, we describe the production and characterization of monoclonal anti-idiotype antibodies against idiotopes on the variable regions of an antibody showing high affinity and specificity to 11-deoxycortisol (11-DC). 11-DC is the biosynthetic precursor of cortisol and a diagnostic index for the assessment of pituitary-adrenal function. BALB/c or A/J mice were repeatedly immunized with the anti-11-DC antibody conjugated with keyhole limpet hemocyanin and their spleen cells were then fused with P3/NS1/1-Ag4-1 myeloma cells. Seven kinds of anti-idiotype antibodies were generated, one of which was a beta-type antibody recognizing the paratope and others which were alpha-type antibodies recognizing the framework region. A noncompetitive ELISA based on idiotype-anti-idiotype reactions was established using one of these alpha-type antibodies in combination with the beta-type antibody and with the anti-11-DC antibody. This noncompetitive assay system provided improved sensitivity (detection limit: 1.0 pg=2.9 fmol), which is approximately 10 times higher than the corresponding competitive enzyme immunoassay, and offered a practical specificity for clinical use. Appropriate serum 11-DC levels were obtained for normal subjects [0.16+/-0.09 (S.D.) microg/l (n=6), ranging from 0.086 to 0.316 microg/l] using the present assay system.

Generation of a novel monoclonal antibody against cortisol-[C-4]-bovine serum albumin conjugate: application to enzyme-linked immunosorbent assay for urinary and serum cortisol

Measurement of cortisol levels in body fluids is important for monitoring pituitary gland and adrenal functions. To develop a specific and standardized enzyme-linked immunosorbent assay (ELISA), a novel monoclonal anti-cortisol antibody has been generated using a reasonably designed haptenic derivative. Spleen cells were prepared from the BALB/c or A/J mouse, which had repeatedly been immunized with a conjugate of 4-(2-carboxyethylthio)cortisol (CET) and bovine serum albumin, to be fused with P3/NS1/1-Ag4-1 myeloma cells. After four fusion experiments, one hybridoma clone secreting a practical antibody has been established. The resulting monoclonal antibody CS#38 (isotype gamma1, kappa) showed an affinity constant (K(a)) for cortisol of 1 x 10(9) M(-1) and provided a practical calibration curve (detection limit, 0.26 ng per assay) in a homologous ELISA system employing horseradish peroxidase-labeled CET as a labeled antigen. Cross-reactivities with related C-21 steroids were acceptably low: 11-deoxycortisol (4.3%), cortisone (4.0%), corticosterone (1.9%), progesterone (1.6%), 17alpha-hydroxyprogesterone (12%), 6beta-hydroxycortisol (8.4%), and tetrahydrocortisol (< 0.1%). Urinary and serum cortisol levels of healthy volunteers were determined by this method after methylene chloride extraction to be 39.0 +/- 17.0 microg/day (n = 7) and 80.8 +/- 38.9 ng/mL (n = 10), respectively, both of which are in the reference range.