AN IMMUNOHISTOCHEMICAL METHOD FOR THE DETECTION OF TUMOR-NECROSIS-FACTOR-ALPHA IN CYTOSPINS OF HUMAN BRONCHOALVEOLAR LAVAGE CELLS

An immunohistochemical method for assessing the level of tumour necros is factor-alpha in alveolar macrophages obtained by brochoalveolar lav age is described. Cytospins of mixed populations of lung cells were in cubated first with a monoclonal antibody to CD68 and then with a speci fic peroxidase-labelled second antibody in a two-step reaction for the detection of the macrophage marker CD68. A second similarly based two -step reaction for the detection of tumour necrosis factor-alpha follo wed. Both reactions were visualized, on completion, using different co loured peroxidase substrates which produced a third colour in the even t of dual deposition of the substrates. Dual substrate deposition was indicative of alveolar macrophages positive for tumour necrosis factor -alpha. This method has provided a specific and reproducible semi-quan titative test for the presence of tumour necrosis factor-alpha in huma n activated alveolar macrophages, which can be performed retrospective ly on clinical material. A range of concentrations of the cytokine has been demonstrated in individual samples. This dual detection method h as the potential for detection of any cell-associated protein product by minor modification of the described method.