Anti-Melanoma (gp100) (Hu) from Mouse (HMB45) – unconj.

HMB45 has been shown to be a very specific marker for melanomas. HMB45 is a mouse monoclonal antibody that reacts against an antigen present in melanocytictumors such as melanomas. It reacts positively against melanocytic tumors but not othertumors, thus signifying specificity and sensitivity. HMB45 is generally thought of as amelanoma specific antibody, however, there are certain exceptions. The antibody also reactspositively against junctional nevus cells but not intra-dermal nevi and against fetal melanocytesbut not normal adult melanocytes. The expression of the HMB45 antigen indicates activemelanosome formation and thus melanocytic differentiation. It is also expressed in normal fetalmelanocytes, but not in normal resting adult melanocytes, regardless of the degree ofpigmentation. Upon activation, adult melanocytes can re-express the HMB45-defined antigen(as it is expressed in fetal melanocytes). Such melanocytes are activated by a variety ofstimuli. For example, HMB45 positive cells have been detected in tissue overlying or adjacentto granulation tissue, hemangiomas, vessel-rich tumor stroma, and basal cell carcinoma. Hairfollicles stain occasionally due to associated stimulated melanocytes. Positive HMB45 staininghas not been observed with melanocytes in lentigines or overlying fibroblastic proliferationssuch as keloids,dermatofibromas and old fibrotic hemangiomas. Non-melanocytic normaltissues do not react with the HMB45 antibody.