A new specific method for measuring S-100B in serum

The S-100 family of proteins are acidic calcium and zinc binding low molecu lar weight proteins mainly present in astrocytes and in a population of oli godendrocytes of the CNS. S100b, an acidic low weight and zinc binding prot ein, has attracted considerable interest due to its release into the cerebr ospinal fluid and blood from brain tissue following brain damage and from m alignant melanomas. A new simple two-step incubation assay has now been ela borated in which two catcher and one tracer monoclonal antibodies are used. The specificity of this assay is high because all the MAbs used bind exclu sively to S-100B, as shown by real-time biospecific interaction analyses. M oreover, the working range of the assay is 0.2-60 mu g/L with a CV of less than 10%; the resulting high sensitivity has been confirmed by clinical stu dies. Time dependence, shaking conditions, lower limit of detection limits, effects of dilution, hook effect, recovery: impression as intra- and inter assay variations, and crossreactivities with S-100Al were tested in order t o obtain a highly reproducible assay Sera from healthy blood donors and pat ients undergoing cardiopulmonary bypass operations were tested with the ass ay Several of the patients undergoing open heart surgery presented measurab le values in this IRMA S-100 assay indicating cerebral effects of open hear t surgery. The test may be used for postoperative monitoring of these patie nts.