Description and Composition of Lanolin
Lanolin is a substance derived from secretions of the sebaceous glands of sheep and functions as a protective coating on wool. This fatlike substance, also called wool grease, may constitute 5 to 25% of the weight of sheared wool. Wool grease is modified to create lanolin and its derivatives. In 1986, Barnett described the chemical structure of lanolin as a wax made of a “highly complex mixture of esters, di-esters, and hydroxyl esters of high molecular weight lanolin alcohols and high molecular weight lanolin acids.” Lanolin alcohols can be broken down further into three main chemical groups: aliphatic alcohols, sterols (including cholesterol), and trimethyl sterols. Lanolin acids are made up of four groups: normal, iso, anteiso, and hydroxyl acids. A mixture of free alcohols constitutes roughly 12% lanolin in addition to trace amounts of free acids and hydrocarbons, ( Table 1 ). Although advanced techniques have been used to determine the nature of many of these components, a large portion of the esters in lanolin have yet to be characterized.
A major difficulty in fully characterizing lanolin is that its composition varies. Breeds of sheep, geographic locations, methods of extraction, and levels of purification may differ. These potentially important variations have several implications in regard to the components of lanolin that cause sensitization in humans. Another problem in understanding allergy to lanolin is that many previous studies have not fully described the lanolin type, allergens, and concentrations or the clinical relevance of positive reactions. For the purpose of this review, we have included details if provided by the authors of the original study. Information not reported is identified as such in the text.
Dermatitis. 2008;19(2):63-72. © 2008 American Contact Dermatitis Society
Cite this: Lanolin Allergy: History, Epidemiology, Responsible Allergens, and Management - Medscape - Apr 01, 2008.