Anti-Human/Mouse PMEL (Clone HMB-45) – Dylight® 594

The extract of pigmented melanoma metastases from lymph nodes

This DyLight® 594 conjugate is formulated in 0.01 M phosphate buffered saline (150 mM NaCl) PBS pH 7.4, 1% BSA and 0.09% sodium azide as a preservative.

Liquid

This DyLight® 594 conjugate is stable when stored at 2-8°C. Do not freeze.

Research Use Only

2-8°C Wet Ice

Red Laser (590 nm)

HMB-45 activity is directed against processed, mature human PMEL protein (also known as gp100, PMEL17, SILV), specifically sialylated PMEL in the fibrillar matrix of Stage II melanosomes. Additionally, HMB-45 stains melanoma and nevocytic lesions with high specificity by recognizing the melanosomal matrix fibers.

Melanocytes are a cell type found in the skin and eyes that produce melanin. PMEL encodes a melanocyte-specific type I transmembrane glycoprotein that is subject to complex posttranslational processing, including modification, cleavage, trafficking and sorting to early melanosomes^{1, 2, 3}. Melanosomes are a type of lysosome-related organelle that produce melanin pigment, and they progress through four stages of maturation³. PMEL plays an essential role in the structural organization of pre-melanosomes and is required for the formation of the internal matrix fibers (fibrils) that define the transition from Stage I to Stage II during melanosome morphogenesis^{1, 2, 3}. Melanin is subsequently synthesized and deposited on those fibrils, resulting in a pigmented internal matrix in mature melanosomes³.

Immunohistochemistry is widely used to differentiate melanomas, a cancer of melanocytes, from other tumors in clinical settings⁴. HMB-45 is commonly used in clinics to detect melanocytic tumors³ because it specifically stains the fibrillar matrix of pre-melanocytes and immature melanosomes^{5, 6}. Although studies have shown that HMB-45 reacts with 56-100% of melanomas^{4, 7} as well as all cases of Spitz tumors ⁷ and atypical melanocytic hyperplasia, HMB-45 does not distinguish between benign and malignant melanocytic proliferations⁷.

HMB-45 was generated in a BALB/c mouse using a portion of an axillary lymph node containing pigmented melanoma metastases as immunogen⁷. The spleen was removed, fused with NS-1 cells, and the resulting hybridoma lines screened against the same melanoma used as immunogen. Deletion of PMEL’s internal proline/serine/threonine-rich repeat (RPT) domain abolishes recognition by HMB-45 as well as PMEL’s capacity to form fibrils³.

Cytoplasmic staining by HMB-45 is observed in 77-100% of primary melanomas and 56-83% of metastatic melanomas. HMB-45 also stains PEComas (i.e., lymphangiomyomatosis, angiomyolipomas, and pulmonary ‘sugar’ tumors), meningeal melanocytomas, sweat gland tumors, clear cell sarcoma of the tendons and aponeuroses as well as some ovarian steroid cell tumors, breast cancers, and renal cell carcinomas, but does not stain non-melanocytic tumors. HMB-45 has poor sensitivity to spindle cell and desmoplastic melanoma.

Pmel 17

1. https://www.ncbi.nlm.nih.gov/gene/6490#gene-expression
2. https://www.uniprot.org/uniprotkb/P40967/entry
3. Hoashi T, Muller J, Vieira WD, et al. J Biol Chem. 281(30):21198-21208. 2006.
4. Ohsie SJ, Sarantopoulos GP, Cochran AJ, et al. J Cutan Pathol. 35(5):433-444. 2008.
5. Taatjes DJ, Arendash-Durand B, von Turkovich M, et al. Arch Pathol Lab Med. 117(3):264-268. 1993.
6. Kapur RP, Bigler SA, Skelly M, et al. J Histochem Cytochem. 40(2):207-212. 1992.
7. Gown AM, Vogel AM, Hoak D, et al. Am J Pathol. 123(2):195-203. 1986.
8. Sheffield MV, Yee H, Dorvault CC, et al. Am J Clin Pathol. 118(6):930-936. 2002.
9. Ramgolam K, Lauriol J, Lalou C, et al. PLoS One. 6(4):e18784. 2011.
10. Matsumoto Y, Horiba K, Usuki J, et al. Am J Respir Cell Mol Biol. 21(3):327-336. 1999.
11. Setty SR, Tenza D, Sviderskaya EV, et al. Nature. 454(7208):1142-1146. 2008.
12. Kawakami A, Sakane F, Imai S, et al. J Invest Dermatol. 128(1):143-150. 2008.
13. Mahmood MN, Lee MW, Linden MD, et al. Mod Pathol. 15(12):1288-1293. 2002.
14. Gleason BC, Nascimento AF. Am J Dermatopathol. 29(1):22-27. 2007.
15. Roberts DW, Newton RA, Leonard JH, et al. J Cell Physiol. 215(2):344-355. 2008.
16. Kawakami Y, Eliyahu S, Delgado CH, et al. Proc Natl Acad Sci U S A. 91(14):6458-6462. 1994.