Antigenic Profile of Muscularis Mucosae and Muscularis Propria of the Urinary Bladder

Background: Differentiation between the muscularis mucosae (MM) and muscularispropria (MP) of the bladder remains challenging. Objective: To identify MM- and MP-specific antigens that could be of potential value for staging of urothelialcarcinomain a pilot study. Method: The expression of 12 protein antigens in 11 human bladder specimens was examined. There were 5 post radical cystectomy specimens and 6 normal bladder autopsy specimens. Antibodies against actin, caldesmon, type IV collagen, cytokeratin, desmin, elastin, fibronectin, filamin, laminin, miotilin, smoothelin, and vimentin were used. Slides were stained with immunohistochemical reagents and assessed using light microscopy. The intensity of the immune reaction within MM and MP was evaluated in a four-level scale as negative, weakly, moderately, or strongly positive. Results: The presence of MM was noticed in 63.6% of the specimens.The expression of desmin, filamin, and smoothelin was stronger within MP compared to MM in all cases. Stronger reaction with anti-type IV collagen antibodies was noticed within MP in 80% of the cases. In the whole study group, the expression of vimentin was stronger within MM than MP. Conclusions: MM and MP cells are of different antigenic characteristics. This can be used in the microscopic diagnostics of selected cases. The results need to be validated in a series of specimens from transurethral resection.