Immunological cross-species reactivity of desmin in fat-storing cells (Ito cells) of vertebrates.

In avian smooth muscle, desmin is a major protein composed of intermediate filaments and is localized at the Z-line of myofibrils. It has been reported that in liver tissue, desmin is restricted to certain smooth muscle cells of the large blood vessels in the portal triads. We have recently identified desmin in fat-storing cells (Ito cells) of the Wistar rat liver by means of immunocytochemical techniques using rabbit IgG antibody to chicken gizzard desmin. We studied the immunologic cross-reactivity of this desmin antibody in fat-storing cells of vertebrates. Fresh liver tissues were obtained from a cyclostome (lamprey), fish (carp, eel, young yellowtail, saurel), amphibians (bullfrog, newt), reptiles (striped snake, viper, soft-shelled turtle), birds (quail, linnet) and mammals (guinea pig, mouse, rat, pig, cat, dog, rhesus monkey, man). Desmin was identified in fat-storing cells by indirect immunofluorescent microscopy of frozen tissue sections. Fat-storing cells of a cyclostome, amphibians, reptiles and birds clearly reacted with this desmin antibody. In mammals, however, fat-storing cells of the rhesus monkey and man were not stained by immunoperoxidase and immunofluorescent techniques. Similarly, the fat-storing cells of fish were not stained.Essentially, these immunocytochemical studies using chicken gizzard desmin antibody provide evidence of the immunologic cross-species reactivity to the desmin found within fat-storing cells of many vertebrates. However, the fat-storing cells of fish, the rhesus monkey and man do not appear to demonstrate cross-reactivity. This finding would suggest either that desmin is immunologically heterogeneous or that there are differences in the accessibility of the antigenic determinants of desmin within the fat-storing cells of the latter species.