Histamine and mucosal mast cells in interstitial cystitis

Area of Science:

• Urology
• Immunology
• Pathology

Background:

• Interstitial cystitis (IC) is a chronic bladder disorder with unknown causes.
• Classic IC, or Hunner's ulcer, is associated with increased mast cells in the bladder wall.
• Mast cells release histamine, a mediator of inflammation.

Purpose of the Study:

• To quantify mast cells and histamine in bladder washings from patients with classic IC versus non-ulcerative IC.
• To investigate the correlation between mast cell numbers and histamine levels in IC.
• To determine histamine content per mast cell in classic IC.

Main Methods:

• Collected bladder washings from 16 classic IC patients and 15 non-ulcerative IC patients.
• Counted mast cells in single cell suspensions from bladder washings.
• Measured histamine concentrations in bladder washings using quantitative methods.

Main Results:

• Classic IC patients had significantly higher mast cell counts (median 2.16 x 10(3) cells/L) and histamine levels (median 14.3 ng/L) in bladder washings.
• Non-ulcerative IC patients showed only occasional mast cells and trace histamine levels.
• A strong positive correlation (r=0.87) was observed between mast cell numbers and histamine content.

Conclusions:

• Elevated mast cells and histamine in bladder washings are characteristic of classic IC (Hunner's ulcer).
• Mast cell degranulation and histamine release are likely key contributors to the pathophysiology of classic IC.
• The findings support the role of mast cells in the inflammatory process of interstitial cystitis.