Detection of intracytoplasmic cytokines by flow cytometry was performed using a fluoresceinated monoclonal antibody directed against CD4+ and CD8+ lymphocytes and a rhodamine-labeled intracytoplasmic monoclonal antibody directed against four cytokines. In this way, the percentage of lymphocytes synthesizing TH1 and TH2 cytokines were identified in nasal polyp lymphocytes and the corresponding peripheral blood lymphocytes of 13 patients.