Mast Cells Are A Marked Source For Complement C3 Products That Associate With Increased Cd11b-Positive Cells In Keratinocyte Skin Carcinomas

By using immunohistochemistry and antibodies that identify complement C3c (in C3 and C3b) or CD11b receptor, we report that the proportion C3c(+) mast cells and the number of CD11b(+) cells are increased in basal cell carcinoma (BCC). Instead, only CD11b(+) cells are increased in squamous cell carcinoma/Bowen's disease, and only slightly so in actinic keratosis. Only C3c(+) mast cells are increased in psoriasis. Furthermore, C3c(+) mast cells correlated positively with CD11b(+) cells, and iC3b immunoreactivity was detected around tryptase(+) mast cells. Therefore, mast cells may convey immunoregulatory signals through C3, C3b, and iC3b to CD11b(+) cells, especially in BCC.