Really old - Palaeoimmunology: Immunohistochemical analysis of extracellular matrix proteins in historic and pre-historic material

In this review, we summarize data concerning the respective preservation an d deterioration of antigenic determinants of various collagenous and non-co llagenous extracellular matrix (ECM) proteins in palaeontologic material of different ages. ECM proteins are the major quantitative constituents of ma mmalian organisms and were, therefore, selected as important representative proteins for these analyses. The specimens, studied by immunofluorescence and immunohistochemical techniques, included the skin of 500-1500 year-old human mummies from Peru, skin and striated muscle from the 5300 year-old gl acier mummy ('Iceman') from Tyrol, Austria, and a 50 million year-old bat w ith preserved soft body parts from the fossil excavation site of Messel, Ge rmany. In frozen sections of the former two sources, epitopes recognized by specific antibodies for triple-helical antigenic determinants of different types of collagen resistant against conventional proteases were preserved, while non-helical domains, as well as the non-collagenous ECM proteins, co uld no longer be demonstrated. The fossil bat, although showing evidence of fibrous, collagen-like structures in conventional histology, revealed no c ollagenous or non-collagenous ECM proteins by any technique. It later turne d out that this was due to the replacement of the original soft parts in th ese fossils by lawns of bacteria. These studies introduced immunological te chniques into palaeontology and opened new approaches for studying physiolo gically- and pathologically-altered structures in tissues of animals and hu mans of considerable historical age. (C) 2001 Elsevier Science Ltd All righ ts reserved.