[Characteristics of heterologous antisera against stromal fibroblasts]

As shown with the use of heterologous rabbit antifibroblast sera (AFS) to stromal mechanocytes of guinea pig, the media from the cultured bone marrow, spleen, and thymus stromal fibroblasts contained specific trypsinoresistant fibroblast protein (AG-1), which was also present in the normal blood serum and on the surface of stromal fibroblasts. AG-1 was insensitive to collagenase effect and apparently differed from the chief surface protein of fibroblasts (CSP). AG-1 is referred to gamma1-globulin, and is probably a new specific surface fibroblast protein. AFS contained also antibodies to the nonspecific protein of fibroblasts (AG-2), alpha1,-globulin related to AG1.