The origin and significance of the Langerhans cell granules.

Preliminary evidence indicates that the Langerhans cell granules (also known as Birbeck granules) may really be intercellular desmosomal discs of the more superficial layers of stratified squamous epithelium that have been taken up by the interdigitating dendritic processes of the Langerhans cells. They should therefore be considered as phagosomes whose only significance is in indicating that their hosts had traversed one or other of the various types of stratified squamous epithelium of the body. When seen in this light variable presence in Langerhans cells or occasional presence in melanocytes or keratinocytes can be satisfactorily explained. Although the Langerhans cells form the first line of immunologic defence as antigen detectors, it is unlikely that their granules play any role at all in the immune response.