Expression patterns of loricrin in various species and tissues

Abstract. In this study we analyzed the expression patterns of loricrin in various species and tissues using immunohistochemistry, immunoblotting and Northern blots. Loricrin is a glycine-, serine- and cysteine-rich protein expressed very late in epidermal differentiation in the granular layers of normal mouse and human epidermis. Later on in differentiation, loricrin becomes cross-linked as a major component into the cornified cell envelope by the formation of N^ɛ -(γ-glutamyl)lysine isopeptide bonds. This process either occurs directly or by the intermediate accumulation in L-keratohyaline granules of mouse epidermis and human acrosyringia. Loricrin was identified in all mammalian species analyzed by virtue of its highly conserved carboxy-terminal sequences revealing an electric mobility of ∼60 kDa in rodents, rabbit and cow and of ∼35 kDa in lamb and human on sodium dodecyl sulfate polyacrylamide gel electrophoresis. Loricrin is expressed in the granular layer of all mammalian orthokeratinizing epithelia tested including oral, esophageal and fore-stomach mucosa of rodents, tracheal squamous metaplasia of vitamin A deficient hamster and estrogen induced squamous vaginal epithelium of ovary ectomized rats. Loricrin is also expressed in a few parakeratinizing epithelia such as BBN [N-butyl-N-(4–hydroxybutyl)nitrosamine]-induced murine bladder carcinoma and a restricted subset of oral and single vaginal epithelial cells in higher mammals. Our results provide further evidence that the program of squamous differentiation in internal epithelia of the upper alimentary tract in rodents and higher mammals differ remarkably. In addition, we also have noted the distinct distribution patterns of human loricrin and involucrin, another major precursor protein of the cornified cell envelope.     

A simple method for assaying the activity of adsorbed tetanus toxoids

The authors have developed a simplified activity test for Tetanus Toxoids Adsorbed, based on the comparison of antitoxin levels in mice 4 weeks after injection of a reference toxoid and of the vaccine to be tested. Titration of tetanus antitoxin is achieved by passive agglutination of turkey RBC sensitized by means of glutaraldehyde. After preliminary experiments establishing feasibility of this method, the authors have obtained reproducible and quantitative results. They observed an increase of the immune response by a booster and an immunostimulation when pertussis component is present. They have found close correlation in immunized mice between the titre of circulating antibodies and the survival/death response after challenge by tetanus toxin as done in the official control. This simplified method using a reduced number of animals, yields, nevertheless, quantified results with confidence limits. Thus it is suitable for laying down a norm and can in many cases take the place of the official potency test which is tedious, expensive and often criticized.