Collagen Type IV

Sources/Clones
Accurate (COL-4), Axcel (CIV22), Biodesign (1o42, MC4HA), Biogenesis (2D8/29), Biogenex (CIV22), Biotec (XCD02), Dako (CIV22), ICN (polyclonal, 1042), Immunotech (CIV22), Milab, Sanbio (SB11), SeraLab (1042) and Serotec (CIV22, PHM-12)

Fixation/Preparation
Most commercial clones of antibodies are immunoreactive in fixed paraffin-embedded sections but only following HIER and enzymatic predigestion with trypsin before the application of the primary antibody.

Background
Basal lamina is mostly formed by a dense 40-60 nm-thick layer called the lamina densa and an electron-lucent layer adjacent to the cell membrane known as the lamina lucida. A loose layer of connective tissue, known as the lamina reticularis, may be present under the lamina densa. Type IV collagen localizes exclusively to the lamina densa and by immunoelectron microscopy is found in both lamina densa and lamina lucida. Laminin has the same distribution but appears to be more intensely localized to the lamina lucida. Other components of basal lamina include heparin sulfate proteoglycan, entactin, fibronectin and type V collagen, the latter probably a stromal rather than basal lamina component.

Applications
Diagnostic applications of collagen type IV immunostaining have mostly centered around the demonstration of basal lamina in invasive tumors, particularly epithelial tumors, and their changes with tumor invasion and metastasis (Birembaut et al, 1985). In particular, the demonstration of an intact basal lamina has been used to distinguish benign glandular proliferations such as microglandular adenosis and sclerosing adenosis from well-differentiated carcinoma like tubular carcinoma of the breast (Raymond & Leong, 1991; Tavassoli & Bratthauer, 1993). Immunostaining for collagen type IV has also been applied to discriminate between C-cell hyperplasia and microscopic medullary carcinoma of the thyroid. The former showed complete investment of the C-cells by a continuous rim of basal lamina, whereas the latter was typified by deficiencies of the basal lamina so that the constituent C-cells were extrafollicular in location (McDermott et al, 1995). There was also focal reduplication of basal lamina, apparently tumor derived. Studies of collagen type IV in the matrix proteins and basal lamina of glomeruli and tubules have been reported (Schleucher & Olgemoller, 1992; Ziyadeh, 1993). Immunostaining for basal lamina has been shown to be a rapid and useful way to distinguish major variants of congenital epidermolysis bullosa, especially when electron microscopy is not available (Bolte & Gonzalez, 1995). Distinctive patterns of basal distribution were recently demonstrated in various types of soft tissue tumors, adding to the diagnostic armamentarium for this group of neoplasms which are often difficult to separate (Leong et al, 1997) (Appendix 1.15). While the presence of basal lamina cannot be used as an absolute discriminant for blood vessels and lymphatic spaces, the latter lack the reduplication of the basal lamina characteristic of blood vessels and generally show thin and discontinuous staining for collagen type IV and laminin (Suthipintawong et al, 1995). The distinctive staining observed around blood vessels has been employed as a marker when performing capillary density measurements (Madsen & Holmskov, 1995).

Comments
Earlier work on basal lamina immunostaining was restricted to the use of immunofluorescence techniques in frozen sections because of the lack of sensitivity of the available antibodies and techniques. The application of HIER combined with proteolytic digestion makes it possible to produce consistent immunostaining of paraffin-embedded, routinely prepared tissue sections.

References
•Birembaut P, Caron Y, Adnet J-J 1985 Usefulness of basement membrane markers in tumoral pathology. Journal of Pathology 145:283-296.

•Bolte C, Gonzalez S 1995 Rapid diagnosis of major variants of congenital epidermolysis bullosa using a monoclonal antibody against collagen type IV. American Journal of Dermatopathology 17:580-583.

•Leong AS-Y, Vinyuvat S, Suthipintawong C, Leong FJ 1997 Patterns of basal lamina immunostaining in soft-tissue and bony tumors. Applied Immunohistochemistry 5: 1-7.

•Madsen K, Holmskov U 1995 Capillary density measurements in skeletal muscle using immunohistochemical staining with anti-collagen type IV antibodies. European Journal of Applied Physiology 71:472-474.

•McDermott MB, Swanson PE, Wick MR 1995 Immunostains for collagen type IV discriminate between C-cell hyperplasia and microscopic medullary carcinoma in multiple endocrine neoplasia, type 2a. Human Pathology 26: 1308-1312.

•Raymond WA, Leong AS-Y 1991 Assessment of invasion in breast lesions using antibodies to basement membrane components and myoepithelial cells. Pathology 23:291-297.

•Schleicher ED, Olgemoller B 1992 Glomerular changes in diabetes mellitus. European Journal of Clinical Chemistry and Clinical Biochemistry 30:635-640.

•Suthipintawong C, Leong, AS-Y, Vinyuvat S 1995 A comparative study of immunomarkers for lymphangiomas and hemangiomas. Applied Immunohistochemistry 3: 239-244.

•Tavassoli FA, Bratthauer GL 1993 Immunohistochemical profile and differential diagnosis of microglandular adenosis. Modern Pathology 6: 318-322.

•Ziyadeh FN 1993 Renal tubular basement membrane and collagen type IV in diabetes mellitus. Kidney International 43:114-120.

Bibliografía
Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.