Aims: To quantify the number of immune cells in the bladder urothelium and concentrations of urinary cytokines in patients with Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS). To identify differences in these measures in IC/BPS patients with Hunner's lesions (IC/BPS-HL) and without Hunner's lesions (IC/BPS-NHL). Methods: Bladder tissue biopsies were obtained from 48 patients with IC/BPS-HL and unaffected controls (UC) and stained with antibodies for various immune cell markers such as

more »

... 8, CD20 and CD56. Levels of cytokines (Interferon (IFN)-γ, Interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL12P70, IL-13, and TNF-α) were measured from normalized urine obtained from 18 IC/BPS-HL, 18 IC/BPS-NHL, and 4 UC. Results: Numbers of CD138+ plasma cells, CD20+ B cells, and CD3+ T cells were significantly increased (50 fold, 30 fold, and an almost 3 fold increase, respectively; p-values: 1.34E-06, 3.26E-04, and 2.52E-6) in the bladders of IC/BPS-HL patients compared to UC. Patients with IC/BPS-HL had significantly elevated urinary levels of IL-6 (p=0.0028) and TNF-α (p=0.009) compared to patients with IC/BPS-NHL and UC. In contrast, IL-12p70 levels were significantly higher in the patients with IC/BPS-NHL than in HL patients (p=0.033). No significant difference in IL-12p70 levels were observed between IC/BPS-HL and UC. Conclusion: Different cytokines were elevated in the urine of IC/BPS patients with and without HL, suggesting differences in underlying disease processes. Elevated levels of CD138+, CD20+, and CD3+ cells in HL indicate B and T-cell involvement in lesion formation. Determining which cytokines and immunological pathways are present in IC/BPS-HL could elucidate the disease mechanism.