An immunohistochemical method for the detection of tumour necrosis factor alpha in cytospins of human bronchoalveolar lavage cells.

An immunohistochemical method for assessing the level of tumour necrosis factor-alpha in alveolar macrophages obtained by brochoalveolar lavage is described. Cytospins of mixed populations of lung cells were incubated first with a monoclonal antibody to CD68 and then with a specific 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 followed. Both reactions were visualized, on completion, using different coloured peroxidase substrates which produced a third colour in the event 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-quantitative test for the presence of tumour necrosis factor-alpha in human activated alveolar macrophages, which can be performed retrospectively on clinical material. A range of concentrations of the cytokine has been demonstrated in individual samples. This dual detection method has the potential for detection of any cell-associated protein product by minor modification of the described method.