title: A colorimetric microassay for opsonins by reduction of NBT in phagocytosing bovine polymorphs.
abstract: The adaptation of the reduction of nitro blue tetrazolium (NBT) by phagocytes to the measurement of the opsonising capacity of serum or milk whey is described. A dose-response curve of the absorbance of solubilised reduced NBT to the concentration of opsonins, along with a close correlation (r = 0.94) between the colorimetric NBT assay and ingestion of group B streptococci (as measured by reduction of [3H]thymidine incorporation by extracellular bacteria), was established. This NBT reduction test, employing 96-well flat-bottom microtitre plates, is simple, semiautomated, requires a low number of PMN, and is applicable to a large number of samples, which renders it useful as a screening test for the opsonising capacity of sera or other biologic fluids.
mesh_terms: D000818:Animals; D002417:Cattle; D009504:Neutrophils / Q000502:physiology*; D009580:Nitroblue Tetrazolium; D009895:Opsonin Proteins / Q000032:analysis*; D010084:Oxidation-Reduction; D010587:Phagocytosis; D013292:Streptococcus agalactiae / Q000276:immunology; D013778:Tetrazolium Salts
chemical_list: D009895:Opsonin Proteins; D013778:Tetrazolium Salts; D009580:Nitroblue Tetrazolium