To investigate local and peripheral changes in Th1 and inflammatory cytokine expression during CYP-induced cystitis, the levels of IFN-γ, IL-12p40, and TNF-α mRNAs expressed by leukocytes isolated from the spleen, iliac lymph nodes and urinary bladder were measured by quantitative RT-PCR analysis. The gene discussed is TNF; the disease is cystitis.