Lysozyme distribution in healthy human skin

TLDR: Forty hospitalized volunteers of both sexes, aged between 19 and 71 years, were studied and lysozyme activity was found to be between 1.25 and 18 lag/ml in serum and between 75 and 198 lag/g wet weigth in skin samples.

Abstract: Lysozyme is present in human skin as well as in other tissues and secretions [2, 4]. Previous personal investigations [1] demonstrated lysozyme activity of between 85 and 195 lag/g wet weight (average 142 lag/g wet weight) in the skin of clinically healthy subjects. Indirect immunofluorescence studies [3] revealed that lysozyme is mainly located in the cytoplasm of epidermal cells and that only small quantities are present along the dermal collagen bundles. Forty hospitalized volunteers of both sexes, aged between 19 and 71 years, were studied. All were free from clinical infections and had only limited traumatic or proliferative skin lesions. Lysozyme activity was determined in both serum and 0.5 mm thick samples of skin taken from the lumbar region and treated according to Binazzi et al. [1]. Histochemical studies were carried out on fine frozen sections of skin removed from the same area and/or from the internal surface of the forearm in an identical condition. Immunofluorescence was performed by the routine technique using antihuman milk muramidase rabbit IgG (Dakopatts, Denmark) and ITCF-labeled antl-~rabbit IgG swine serum (Dakopatts, Denmark). The peroxidase conjugate method (Table 1) was used for the immunoperoxidase studies. Controls were performed by absorbing the primary anti-human muramidase antiserum on purified human milk lysozyme before immunostaining, thus blocking the reactivity for muramidase. Lysozyme activity was found to be between 1.25 and 18 lag/ml (average 5.15 lag/M) in serum and between 75 and 198 lag/g wet weigth (average 119.5 lag/g wet weight) in skin samples. These results did not show significant differences with respect to those previously reported [1].