A new 'total' activin B enzyme-linked immunosorbent assay (ELISA): development and validation for human samples

There are currently no sensitive and specific assays for activin B that could be utilized to study human biological fluids. The aim of this project was to develop and validate a 'total' activin B ELISA for use with human biological fluids and establish concentrations of activin B in the circulation and fluids from the reproductive organs.

The new ELISA was validated and then used to measure activin B levels in the circulation of healthy participants, IVF patients, pregnant women and in ovarian follicular fluid and seminal plasma.

Healthy adult subjects (n = 143), subjects from an IVF clinic (n = 27) and pregnancy groups (n = 29) were sampled.

The sensitivity of the assay was 0.019 ng/ml. Validation of the activin B ELISA showed good recovery (90.7 +/- 9.8%) and linearity in biological fluid and cell culture media and low cross-reactivity with related analytes (inhibin B = 0.077% and activin A = 0.0034%). There was a negative correlation between activin B concentration (r = -0.281, P < 0.011) and females with increasing age. Patients attending IVF clinics had significantly lower levels of activin B compared with gender-matched control subjects. Ovarian follicular fluid and seminal plasma had 50-80 fold higher levels of activin B (mean = 5.35 and 3.66 ng/ml respectively) than sera (mean = 0.071 ng/ml).

This fully validated ELISA for activin B offers a tremendous utility for measuring this protein in a variety of normal physiological processes and in various clinical pathologies.