Expressions And Significance Of Surface Markers Of Immunocytes And Substance P In Fetal Skin

Objective To investigate the differences in the distribution, amount and morphology of immunocytes such as macrophages, lymphocytes, Langerhans cells and substance P positive cells in fetal skin, normal adult skin and hypertrophic scar, and probe into their roles in fetal scarless wound healing.Methods Skin specimens obtained from 10 induced labor fetus(16 to 33 weeks gestation) because of the accidents of pregnant women, 7 adults and 18 cases of hypertrophic scar in different stages were collected to detect the expressions and distributions of CD68, CD3, CD1a and substance P with immunohistochemical assay. Mast cells were detected with toluidine blue stain.Results 1.The expression of CD68 (the surface marker of macrophage cell) in fetal skin was significantly lower than that in normal adult skin, and its expression in normal adult skin was lower than that in hypertrophic scar. The number of macrophage cells in fetal skin increased gradually with the increase of gestational ages, but rapidly rose during 24 to 28 weeks gestation, and then approached to the "platform" stage. 2. No expressions of CD3 (the surface marker of T lymphocyte) and CD1a (the surface marker of Langerhans cell) were found in fetal skin during 16 to 33 weeks gestation, but they were significantly lower in normal skin than those in hypertrophic scar. 3. No typical mast cells were found in fetal skin and the number of mast cells was lower in normal skin than that in hypertrophic scar. 4. SP positive cells appeared in 22 weeks gestation and the number climbed swiftly to adult level only with light staining.Conclusion The decrease of CD68 and lack of CD3 and CD1a in fetal skin suggests that the deficiency of immunocytes may play an important role in the achievement of scarless wound healing. There may be a close connection between the expression of CD68 in fetal skin and the wound healing transition from fetal-pattern to adult-pattern. Suppression of immunocytes may contribute to prevention and treatment of hypertrophic scar. Substance P may participate in transition of the pattern of wound healing as well. The difference of the immunocytes in amount may be one of the main reasons for fetal-pattern and adult-pattern wound healing. Scar formation is proved to have close relations with immune-neurologic system.