Radioimmunoassay for pantothenic acid in blood and other tissues.

We describe a radioimmunoassay for pantothenic acid in biological tissues. D-Pantothenic acid was conjugated with bovine serum albumin by use of a bromoacetyl derivative of pantothenic acid, and antibody to this antigen was raised by injecting it into the foot pads of rabbits. For the radioimmunoassay, a 100-fold dilution of the resulting antiserum was incubated with radiolabeled pantothentic acid. The antibodies were precipitated and dissolved, and the radioactivity of the solution was measured in a liquid scintillation counter. Between 5 and 125 ng of pantothenic acid can be detected in 75 muL of tissue extract. Validation included recovery and precision studies, parallelism with tissue extracts, and competitive binding studies. Results of the radioimmunoassay and those of microbiological assay with use of Lactobacillus plantarum correlated well (r = 0.80).