Abstract
Four monoclonal antibodies designated CK1 - CK4 were obtained from fusions of mouse myeloma F0 cells with spleen cells from BALB/c mice immunized with cytoskeletal preparations made by treatment of human HeLa cells with non-ionic detergents. These IgG1 type antibodies all recognize, in immune blots, cytokeratin 18 (45 kd, pI 5.7) in the catalogue of 19 human cytokeratin species developed by Moll et al. (1982). Immunofluorescence microscopy on human material shows that CK1 - CK4 stain a wide variety of simple epithelia (e.g., intestine, respiratory and urinary systems, liver, glandular epithelia) but do not stain stratified squamous epithelia (e.g., oesophagus, epidermis) or non-epithelial cells. The immunofluorescence results, developed mainly by gel electrophoresis, support the concept of cytokeratin divergence in different epithelia and clarify, for cytokeratin 18, some unsolved problems posed by high tissue complexity. CK2 appears specific for human, CK1 and CK3 for primates, while CK4 shows broad cross-species reactivity. Thus, CK1 - CK4 appear to be valuable tools for cytokeratin typing and initial experiments also suggest that they can be used to further subdivide human tumours of epithelial origin.