Sources/Clones
Accurate (P-29, 4LJ, SB19), AMS Biotech, Biodesign, Biogenesis (501, 503, 504), Biogenex (045), Biomeda, Caltag (SB19), Camon, Chemicon, Dako (PASE/4LJ, polyclonal), Diagnostic, Immunotech (PAP29), Milab/Med, Novocastra, Oxoid (PAY376), Sanbio (4LJ), Saxon, Seralab (8), Serotec, Sigma (PAP12, PAP29) and Zymed (ZMPAP4).
Fixation/Preparation
Both poly- and monoclonal antibodies are immunoreactive in fixed, paraffin-embedded tissues and staining is enhanced by heat-induced epitope retrieval.
Background
Acid phosphatases hydrolyze phosphoric acid esters at acid pH. They are found in a variety of tissues and differences in electrophoretic patterns or sensitivity to isoenzyme inhibitors allowed the distinction of isoforms of the enzyme to specific tissues. Normal prostatic tissue contains several isoforms but only two are secreted in the seminal fluid. Acid phosphatase activity is mainly localized to the lysosomes of prostatic epithelial cells and ultrastructurally is identified within microvilli of the apical cell membranes and in the secretory granules at the supranuclear or apical regions of benign cells. Although synthesized in rough endoplasmic reticulum, PAP is not demonstrable in this site and because it is only recognized in lysosomes it is assumed that antibodies recognize PAP only when packaged into granules. Basal cells are negative for PAP. Serum levels of the enzyme reflect the amount of enzyme released into the circulation and are dependent on the tumor mass and also the rate of synthesis and access to the intravascular space. Low levels of the enzyme have been suggested to represent low rates of synthesis by poorly differentiated tumors.
Applications
PAP immunostaining is a useful discriminator for prostatic tissue and its diagnostic specificity and sensitivity are increased when used in a panel in conjunction with PSA and CD57 (Leu 7). Like PSA, immunoreactivity for PAP is more intense and homogeneous in benign prostatic tissue than in prostatic carcinoma. PAP is localized within prostatic acini and ducts, although the latter tend to show weaker and more heterogeneous staining (Leong & Gown, 1993).
Rare cases of squamous metaplasia of the prostatic epithelium show staining for PAP. There is weak positivity in seminal vesicle epithelium and like PSA, periurethral glands in both men and women are positive for the enzyme. Other non-prostatic tissues which may show PAP immunostaining are anal glands in men, neuroendocrine cells of the rectum, transitional epithelium and Von Brun's nests of the bladder, renal tubular epithelium, pancreatic islet cells, hepatocytes, gastric parietal cells and mammary ductal epithelium. Neutrophils show the strongest concentration of PAP among non-prostatic tissues. Neoplasms that show crossreactivity are mainly those derived from the cloaca, such as urinary bladder, periurethral glands and colon and neuroendocrine tumors (Wahol & Longtime, 1985; Epstein, 1993).
Comments
In general, PAP is relatively specific for prostatic neoplasms. However, because of the crossreactivity of both PAP and prostate-specific antigen (PSA)
with the tissues listed above, it is still best to use PAP in conjunction with PSA, particularly in the context of a tumor in the perineum whose differential diagnosis includes prostatic carcinoma, transitional carcinoma and adenocarcinoma of the bladder and rectal carcinoma (Leong et al, 1996). Besides PAP and PSA, the panel should include an antibody to high molecular weight cytokeratin, CK 20 and CK 7 (Appendix 1.14).
Acid phosphatase consists of several isoenzymes and polyclonal antibodies to PAP crossreact with isoenzyme 4, which is present in small amounts in most human tissues. Furthermore, polyclonal antibodies recognize several antigenic sites and may produce weak background staining but this is not seen with monoclonal antibodies that recognize only one antigenic site. Clone PASE/4LJ from Dako produces satisfactory results.
References
•Epstein JI 1993. PSA and PAP as immunohistochemical markers in prostatic cancer. Urologic Clinics of North America; 20:757-770.
•Leong AS-Y, Gown AM 1993. Immunohistochemistry of "solid" tumors: poorly differentiated round cell and spindle cell tumors - I. In: Leong AS-Y (ed) Applied immunohistochemistry for surgical pathologists. London: Edward Arnold, pp24-72.
•Leong FJ, Leong AS-Y, Swift J 1996. Signet ring carcinoma of the prostate. Pathology, Research and Practice; 192: 1232-1238.
•Wahol MJ, Longtime JA 1985. The ultrastructural localization of prostate specific antigen and prostatic acid phosphatase in hyperplastic and neoplastic human prostates. Journal of Urology; 134: 607-611.
Bibliografia
Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.
Accurate (P-29, 4LJ, SB19), AMS Biotech, Biodesign, Biogenesis (501, 503, 504), Biogenex (045), Biomeda, Caltag (SB19), Camon, Chemicon, Dako (PASE/4LJ, polyclonal), Diagnostic, Immunotech (PAP29), Milab/Med, Novocastra, Oxoid (PAY376), Sanbio (4LJ), Saxon, Seralab (8), Serotec, Sigma (PAP12, PAP29) and Zymed (ZMPAP4).
Fixation/Preparation
Both poly- and monoclonal antibodies are immunoreactive in fixed, paraffin-embedded tissues and staining is enhanced by heat-induced epitope retrieval.
Background
Acid phosphatases hydrolyze phosphoric acid esters at acid pH. They are found in a variety of tissues and differences in electrophoretic patterns or sensitivity to isoenzyme inhibitors allowed the distinction of isoforms of the enzyme to specific tissues. Normal prostatic tissue contains several isoforms but only two are secreted in the seminal fluid. Acid phosphatase activity is mainly localized to the lysosomes of prostatic epithelial cells and ultrastructurally is identified within microvilli of the apical cell membranes and in the secretory granules at the supranuclear or apical regions of benign cells. Although synthesized in rough endoplasmic reticulum, PAP is not demonstrable in this site and because it is only recognized in lysosomes it is assumed that antibodies recognize PAP only when packaged into granules. Basal cells are negative for PAP. Serum levels of the enzyme reflect the amount of enzyme released into the circulation and are dependent on the tumor mass and also the rate of synthesis and access to the intravascular space. Low levels of the enzyme have been suggested to represent low rates of synthesis by poorly differentiated tumors.
Applications
PAP immunostaining is a useful discriminator for prostatic tissue and its diagnostic specificity and sensitivity are increased when used in a panel in conjunction with PSA and CD57 (Leu 7). Like PSA, immunoreactivity for PAP is more intense and homogeneous in benign prostatic tissue than in prostatic carcinoma. PAP is localized within prostatic acini and ducts, although the latter tend to show weaker and more heterogeneous staining (Leong & Gown, 1993).
Rare cases of squamous metaplasia of the prostatic epithelium show staining for PAP. There is weak positivity in seminal vesicle epithelium and like PSA, periurethral glands in both men and women are positive for the enzyme. Other non-prostatic tissues which may show PAP immunostaining are anal glands in men, neuroendocrine cells of the rectum, transitional epithelium and Von Brun's nests of the bladder, renal tubular epithelium, pancreatic islet cells, hepatocytes, gastric parietal cells and mammary ductal epithelium. Neutrophils show the strongest concentration of PAP among non-prostatic tissues. Neoplasms that show crossreactivity are mainly those derived from the cloaca, such as urinary bladder, periurethral glands and colon and neuroendocrine tumors (Wahol & Longtime, 1985; Epstein, 1993).
Comments
In general, PAP is relatively specific for prostatic neoplasms. However, because of the crossreactivity of both PAP and prostate-specific antigen (PSA)
with the tissues listed above, it is still best to use PAP in conjunction with PSA, particularly in the context of a tumor in the perineum whose differential diagnosis includes prostatic carcinoma, transitional carcinoma and adenocarcinoma of the bladder and rectal carcinoma (Leong et al, 1996). Besides PAP and PSA, the panel should include an antibody to high molecular weight cytokeratin, CK 20 and CK 7 (Appendix 1.14).
Acid phosphatase consists of several isoenzymes and polyclonal antibodies to PAP crossreact with isoenzyme 4, which is present in small amounts in most human tissues. Furthermore, polyclonal antibodies recognize several antigenic sites and may produce weak background staining but this is not seen with monoclonal antibodies that recognize only one antigenic site. Clone PASE/4LJ from Dako produces satisfactory results.
References
•Epstein JI 1993. PSA and PAP as immunohistochemical markers in prostatic cancer. Urologic Clinics of North America; 20:757-770.
•Leong AS-Y, Gown AM 1993. Immunohistochemistry of "solid" tumors: poorly differentiated round cell and spindle cell tumors - I. In: Leong AS-Y (ed) Applied immunohistochemistry for surgical pathologists. London: Edward Arnold, pp24-72.
•Leong FJ, Leong AS-Y, Swift J 1996. Signet ring carcinoma of the prostate. Pathology, Research and Practice; 192: 1232-1238.
•Wahol MJ, Longtime JA 1985. The ultrastructural localization of prostate specific antigen and prostatic acid phosphatase in hyperplastic and neoplastic human prostates. Journal of Urology; 134: 607-611.
Bibliografia
Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.
