Concomitant immunohistochemical localization of fibronectin and collagen in schistosome granulomata.

Affinity purified antibodies to human collagen type I and III and antihuman fibronectin, were employed immunohistochemically on formalin-fixed, paraffin-embedded human tissue containing schistosome granulomata. The distribution of the three connective tissue proteins was studied in 45 biopsies in which there was Schistosoma haematobium (30) and Schistosoma mansoni (15) infestation. The granulomata were divided into early, intermediate and late according to the proportion of inflammatory cell types and the degree of fibrous tissue deposition. Only fibronectin was detected in the early granuloma where macrophages are the main cell type. In the intermediate granuloma both fibronectin and collagen type III were localized along reticulin positive fibres; spindle cells, (presumptive fibroblasts) and macrophages were the cell types present at this stage. Collagen type I was mainly localized in the late granuloma. Hyalinized connective tissue was negative for the three proteins. The loose connective tissue and walls of blood vessels were constantly stained for fibronectin and collagen type III in normal areas distant from granulomata. These results raise the possibility of using localization of fibronectin and collagen as a means to stage the duration of chronic fibrotic diseases.