Anti-Human/Mouse PMEL (Clone HMB-45) – Purified No Carrier Protein - 25 µg

Primary Monoclonal Antibodies>Tumor Markers

2 - 8°C Wet Ice

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 melanosomes1, 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 morphogenesis1, 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 melanosomes5, 6. Although studies have shown that HMB-45 reacts with 56-100% of melanomas4, 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.

≥1.0 mg/ml

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.