Polybrominated biphenyls in model and environmentally contaminated human blood: protein binding and immunotoxicological studies.

A review and summary is given of analytical, biochemical, and immunological studies made following an immunodiagnostic investigation which revealed significant decreases in the numbers, and changes in the functional integrity, of both T-and B-lymphocytes in a group of Michigan dairy farmers exposed to polybrominated biphenyls (PBB) which had been inadvertently introduced into the food chain in 1973. A quantification technique based on selected ion monitoring of bromine anions, obtained in negative chemical ionization, permitted determination of 10-35 pg of individual PBB congener per mL serum, a 20-fold improvement over electron capture gas chromatography. An in vitro spiked system was established and shown to be a representative model of environmentally contaminated blood. Immunoprecipitation followed by mass spectrometric quantification determined that the distribution of PBB among plasma, erythrocytes, mononucleocytes and polymorphonucleocytes was 89:9:less than 1:less than 1. In plasma 80% of the PBB was bound to apolipoproteins B and A in a 3:1 ratio. No preferential absorption of PBB congeners was found in the blood compartments suggesting that changes in the relative abundances of PBB congeners observed in longitudinal studies on Michigan subjects reflect differences in excretion rates or metabolism. A repeat in 1981 of the immunodiagnostic tests conducted in 1976 revealed a virtually complete persistence of the immune dysfunctions in the Michigan farmers exposed to PBB a decade ago.