The influence of mast cells on reparative regeneration of tissues characterized by various degrees of immune privilege

Abstract

Tissues characterized by various degrees of immune privilege are thought to differ in repair processes. This circumstance may be due to mast cells (MCs) that occur in all tissues of the body, secrete a wide range of biologically active compounds, and play an important role in the regulation of repair processes. The present paper reports the results of investigations of morphometric parameters and functional activity of MCs in tissues characterized by various degrees of immune privilege such as the skin and testis. It was shown that MCs migrate into the skin in the early stages after damage, followed by a slow increase in the synthetic activity and degranulation index of MCs for 30 days. In the case of the testis, the MC degranulation index increases immediately after damage, with a pronounced migration of MCs being absent. The stabilization of MC membranes with ketotifen inhibits skin repair; namely, there is no increase in the thickness of the dermis and epidermis and the number of fibroblasts and collagen fibers, along with slowing down of the scar formation. Meanwhile, the MC inactivation contributes to the reparative regeneration of the testis. This circumstance is confirmed by a significant reduction of the number of nonfunctioning tubules and an increase in the number of normal spermatogonia, which are a proliferative pool for all subsequent stages of spermatogenesis. Thereby, the number and the functional state of MCs influences the repair processes in tissues characterized by various degrees of immune privilege.