| 摘要 |
CD44 is a family of glycoproteins involved in cell-cell and cell-matrix interactions. In addition to the major 90 kD form present on most hematopoietic cells, larger forms are found on keratinocytes and carcinoma cell lines. These bigger isoforms of CD44 arise by alternative splicing that results in insertion of one or more of the "variant" exons into the extracellular part of the 90 kD constant form of the molecule. Antibodies were raised against a synthetic peptide containing a sequence encoded by the human exon 6A mAb thus obtained (designated Var3.1) strongly reacted with the plasma membranes of squamous cells in upper layers of skin and tonsil surface epithelia. Weaker staining was seen in germinal centers, vascular endothelia and enterocytes. CD44v6 was absent from tissue leukocytes and connective tissue components. In comparison, Hermes-3 epitope (on the constant part) containing forms of CD44 were preferentially localized in basal layers of epithelia, present on the surface of most leukocytes and connective tissue cells, and undetectable on the luminal surface of high endothelial venules. In benign neoplasms, epithelial cells stained with mAb Var3.1 like in normal tissues. In contrast, immunostaining of 30 squamous carcinoma specimens (both primary and metastatic lesions) revealed that malignant transformation resulted in down-regulation or disappearance of Var3.1 epitope, but in majority of cases, not in diminished expression of the Hermes-3 epitope. An examination of serum samples from normal individuals and from patients with inflammatory diseases indicated that CD44v6 was increased in samples from patients with rheumatoid arthritis or inflammatory bowel disease. |
