Sources/Clones
Accurate (GA-5, 6F2, polyclonal), Amersham, Biodesign (DP46.10, GF-01), Biogenesis (GF-01, polyclonal), Biogenex (GA-5, polyclonal), Chemicon (monoclonal, polyclonal), Cymbus Bioscience (polyclonal), Dako (6F2, polyclonal), Enzo, EY Labs, ICN (polyclonal), Immunotech (DP46.10), Milab (polyclonal), Novocastra, Sanbio (6F2, polyclonal), Saxo (polyclonal), Seralab (GA-5), Serotec (GA5, MIG-G2), Sigma (GA-5, polyclonal), Signet and Zymed (ZSGFAP2, ZCG29).
Fixation/Preparation
Glial fibrillary acidic protein (GFAP) is relatively resilient to fixation and most antibodies are immunoreactive in routinely fixed and processed tissue sections. GFAP staining seems more consistent after fixation in Bouin's fixative. Monoclonal antibodies are more fixative sensitive and polyclonal antibodies show more intense and more extensive staining. GFAP immunoreactivity is mildly enhanced by HIER.
Background
GFAP is an intermediate filament (IF) protein of astroglia and belongs to the type III subclass of IF proteins. Like other IF proteins, GFAP is composed of an amino terminal head domain, a central rod domain and a carboxy terminal tail domain. GFAP, with a molecular mass of 50 kD, has the smallest head domain among the class III IF proteins. Despite its insolubility, GFAP is in dynamic equilibrium between assembled filaments and unassembled subunits. As with other IF proteins, assembly of GFAP is regulated by phosphorylation-dephosphorylation of the head domain by alteration of its charge. The frequent copolymerization of GFAP with vimentin IF in immature, reactive or radial glia indicates that vimentin has an important role in the build-up of the glial architecture (Inagaki et al, 1994). The human GFAP gene is localized to chromosome 17.
Applications
In the central nervous system, astrocytes, rare ependymal cells and cerebellar radial glia express GFAP (Appendix 1.2). While mature oligodendrocytes do not. GFAP or a GFAP-like protein is also found in Schwann cells, enteric glia, cells in all portions of the pituitary, cartilage, the iris and lens epithelium and the fat-storing cells of the liver. While monoclonal antibodies are said to recognize the GFAP epitope exclusively, there may be crossreactivity with common epitopes shared by other IFs like neurofilaments and vimentin.
Immunohistochemical staining of GFAP has proven use in the identification of benign astrocytes and neoplastic cells of glial lineage (Sillevis-Smitt et al, 1993). Its application to the developing nervous system has contributed to our understanding of the histogenesis of neural tissue and its identification in various forms of injury and neoplasia has helped in the understanding of the role of astrocytes in these processes.
While it was initially thought that the GFAP expression in salivary gland tissues and pleomorphic adenomas was in myoepithelial cells (Lee et al, 1993), more recent evidence from developmental and cell culture studies indicates that GFAP is expressed in the epithelial cells, the myoepithelial cells being uniformly negative for the antigen (Okura et al, 1996). GFAP has been demonstrated in cartilage cells in culture (Benjamin et al, 1994) but do not appear to occur in chondrosarcomas and mesenchymal chondrosarcomas (Swanson et al, 1990) and in vivo and immunohistochemical detection of GFAP is used to identify chordomas. Choroid plexus tumors (Radotra et al, 1994) and ependymomas express GFAP in addition to S100 protein and, occasionally, cytokeratin and epithelial membrane antigen. In the setting of vacuolated clear cell tumors occurring in the retroperitoneal space, GFAP positivity would serve to identify chordoma and ependymoma from other mimics, including renal cell carcinoma and colorectal carcinoma (Coffin et al, 1993).
Comments
Polyclonal antibodies to GFAP produce more intense and more extensive staining than monoclonal antibodies (Wittchow & Landas, 1991).
References
•Benjamin M, Archer CW, Ralphs JR 1994. Cytoskeleton of cartilage cells. Microscopy Research Technology 28:372-377.
•Coffin CM, Swanson PE, Wick MR, Dehner LP 1993. An immunohistochemical comparison of chordoma with renal cell carcinoma, colorectal adenocarcinoma, and myxopapillary ependymoma: a potential diagnostic dilemma in the diminutive biopsy. Modern Pathology 5: 531-538.
•Inagaki M, Nakamura Y, Takeda M et al 1994. Glial fibrillary acidic protein: dynamic property and regulation by phosphorylation. Brain Pathology 4:239-243.
•Lee SK, Kim EC, Chi JG et al 1993. Immunohistochemical detection of S-100 alpha, S-100 beta proteins, glial fibrillary acidic protein, and neuron specific enolase in the prenatal and adult human salivary gland. Pathology Research and Practice 189:1036-1043.
•Okura M, Hiranuma T, Tominaga G et al 1996. Expression of S-100 protein and glial fibrillary acidic protein in cultured submandibular gland epithelial cells and salivary gland tissues. American Journal of Pathology 148:1709-1716.
•Radotra BD, Joshi K, Kak VK, Banerjee AK 1994. Choroid plexus tumors - an immunohistochemical analysis with review of literature. Indian Journal of Pathology and Microbiology 37: 9-19.
•Sillevis-Smitt PA, Van Der Loos C, De Jong VJM, Troost D 1993. Tissue fixation methods alter the immunohistochemical demonstrability of neurofilament proteins, synaptophysin, and glial fibrillary acidic protein in human cerebellum. Acta Histochemia 95: 13-21.
•Swanson PE, Lillemoe TJ, Manivell C, Wick MR 1990. Mesenchymal chondrosarcoma. An immunohistochemical study. Archives of Pathology and Laboratory Medicine 114: 943-948.
•Wittchow R, Landas SK 1991. Glial fibrillary acidic protein expression in pleomorphic adenoma, chordoma and astrocytoma. A comparison of three antibodies. Archives of Pathology and Laboratory Medicine 115: 1030-1033.
Bibliografía
Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.
Accurate (GA-5, 6F2, polyclonal), Amersham, Biodesign (DP46.10, GF-01), Biogenesis (GF-01, polyclonal), Biogenex (GA-5, polyclonal), Chemicon (monoclonal, polyclonal), Cymbus Bioscience (polyclonal), Dako (6F2, polyclonal), Enzo, EY Labs, ICN (polyclonal), Immunotech (DP46.10), Milab (polyclonal), Novocastra, Sanbio (6F2, polyclonal), Saxo (polyclonal), Seralab (GA-5), Serotec (GA5, MIG-G2), Sigma (GA-5, polyclonal), Signet and Zymed (ZSGFAP2, ZCG29).
Fixation/Preparation
Glial fibrillary acidic protein (GFAP) is relatively resilient to fixation and most antibodies are immunoreactive in routinely fixed and processed tissue sections. GFAP staining seems more consistent after fixation in Bouin's fixative. Monoclonal antibodies are more fixative sensitive and polyclonal antibodies show more intense and more extensive staining. GFAP immunoreactivity is mildly enhanced by HIER.
Background
GFAP is an intermediate filament (IF) protein of astroglia and belongs to the type III subclass of IF proteins. Like other IF proteins, GFAP is composed of an amino terminal head domain, a central rod domain and a carboxy terminal tail domain. GFAP, with a molecular mass of 50 kD, has the smallest head domain among the class III IF proteins. Despite its insolubility, GFAP is in dynamic equilibrium between assembled filaments and unassembled subunits. As with other IF proteins, assembly of GFAP is regulated by phosphorylation-dephosphorylation of the head domain by alteration of its charge. The frequent copolymerization of GFAP with vimentin IF in immature, reactive or radial glia indicates that vimentin has an important role in the build-up of the glial architecture (Inagaki et al, 1994). The human GFAP gene is localized to chromosome 17.
Applications
In the central nervous system, astrocytes, rare ependymal cells and cerebellar radial glia express GFAP (Appendix 1.2). While mature oligodendrocytes do not. GFAP or a GFAP-like protein is also found in Schwann cells, enteric glia, cells in all portions of the pituitary, cartilage, the iris and lens epithelium and the fat-storing cells of the liver. While monoclonal antibodies are said to recognize the GFAP epitope exclusively, there may be crossreactivity with common epitopes shared by other IFs like neurofilaments and vimentin.
Immunohistochemical staining of GFAP has proven use in the identification of benign astrocytes and neoplastic cells of glial lineage (Sillevis-Smitt et al, 1993). Its application to the developing nervous system has contributed to our understanding of the histogenesis of neural tissue and its identification in various forms of injury and neoplasia has helped in the understanding of the role of astrocytes in these processes.
While it was initially thought that the GFAP expression in salivary gland tissues and pleomorphic adenomas was in myoepithelial cells (Lee et al, 1993), more recent evidence from developmental and cell culture studies indicates that GFAP is expressed in the epithelial cells, the myoepithelial cells being uniformly negative for the antigen (Okura et al, 1996). GFAP has been demonstrated in cartilage cells in culture (Benjamin et al, 1994) but do not appear to occur in chondrosarcomas and mesenchymal chondrosarcomas (Swanson et al, 1990) and in vivo and immunohistochemical detection of GFAP is used to identify chordomas. Choroid plexus tumors (Radotra et al, 1994) and ependymomas express GFAP in addition to S100 protein and, occasionally, cytokeratin and epithelial membrane antigen. In the setting of vacuolated clear cell tumors occurring in the retroperitoneal space, GFAP positivity would serve to identify chordoma and ependymoma from other mimics, including renal cell carcinoma and colorectal carcinoma (Coffin et al, 1993).
Comments
Polyclonal antibodies to GFAP produce more intense and more extensive staining than monoclonal antibodies (Wittchow & Landas, 1991).
References
•Benjamin M, Archer CW, Ralphs JR 1994. Cytoskeleton of cartilage cells. Microscopy Research Technology 28:372-377.
•Coffin CM, Swanson PE, Wick MR, Dehner LP 1993. An immunohistochemical comparison of chordoma with renal cell carcinoma, colorectal adenocarcinoma, and myxopapillary ependymoma: a potential diagnostic dilemma in the diminutive biopsy. Modern Pathology 5: 531-538.
•Inagaki M, Nakamura Y, Takeda M et al 1994. Glial fibrillary acidic protein: dynamic property and regulation by phosphorylation. Brain Pathology 4:239-243.
•Lee SK, Kim EC, Chi JG et al 1993. Immunohistochemical detection of S-100 alpha, S-100 beta proteins, glial fibrillary acidic protein, and neuron specific enolase in the prenatal and adult human salivary gland. Pathology Research and Practice 189:1036-1043.
•Okura M, Hiranuma T, Tominaga G et al 1996. Expression of S-100 protein and glial fibrillary acidic protein in cultured submandibular gland epithelial cells and salivary gland tissues. American Journal of Pathology 148:1709-1716.
•Radotra BD, Joshi K, Kak VK, Banerjee AK 1994. Choroid plexus tumors - an immunohistochemical analysis with review of literature. Indian Journal of Pathology and Microbiology 37: 9-19.
•Sillevis-Smitt PA, Van Der Loos C, De Jong VJM, Troost D 1993. Tissue fixation methods alter the immunohistochemical demonstrability of neurofilament proteins, synaptophysin, and glial fibrillary acidic protein in human cerebellum. Acta Histochemia 95: 13-21.
•Swanson PE, Lillemoe TJ, Manivell C, Wick MR 1990. Mesenchymal chondrosarcoma. An immunohistochemical study. Archives of Pathology and Laboratory Medicine 114: 943-948.
•Wittchow R, Landas SK 1991. Glial fibrillary acidic protein expression in pleomorphic adenoma, chordoma and astrocytoma. A comparison of three antibodies. Archives of Pathology and Laboratory Medicine 115: 1030-1033.
Bibliografía
Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.
