A simple, sensitive and widely applicable ELISA for S100B: Methodological features of the measurement of this glial protein

S100B expression, particularly extracellular S100B, is used as a parameter of glial activation and/or death in several situations of brain injury. Several immunoassays for S100B measurement are available, which differ with regard to specificity, sensitivity, sample application, and, of course, economic costs. We standardized two protocols for S100B measurement (range between 1.9 pg and 10 ng/mL) in human and rat samples from brain and adipose tissues, blood serum, cerebrospinal fluid, urine and cell culture. Abundance and secretion of this protein in adipose tissue reinforces the caution about its origin in blood serum. Interestingly, S100B recognition was affected by the redox status of the protein. This aspect should be considered in S100B measurement, assuming that oxidized and reduced forms possibly coexist in vivo and the equilibrium can be modified by oxidative stress of physiological or pathological conditions or even by obtaining sample conditions.