COMPARISON OF MELANOMA ANTIGEN RECOGNIZED BY T-CELLS (MART-1) TO HMB-45 - ADDITIONAL EVIDENCE TO SUPPORT A COMMON LINEAGE FOR ANGIOMYOLIPOMA, LYMPHANGIOMYOMATOSIS, AND CLEAR-CELL SUGAR TUMOR

The antibody to the melanoma antigen recognized by T cells (anti-MART- 1, clone M2-7C10) is a newly described antibody to a transmembrane pro tein previously detected only in normal skin melanocytes, retinal tiss ue, and malignant melanoma (MM), This antibody is the basis for ongoin g immunotherapy protocols at the National Institutes of Health/Nationa l Cancer Institute. HMB-45, an antibody directed against a premelanoso me glycoprotein, although used predominantly for the diagnosis of MM, has shown consistent staining in angiomyolipoma (AML), lymphangiomyoma /lymphangiomyomatosis (LAM), and clear cell sugar tumor (CCST), a grou p of tumors proposed to be related on the basis of their common periva scular epithelioid cells, which exhibit various degrees of smooth musc le differentiation, melanogenesis, and intracytoplasmic membrane bound granules. To compare the immunoreactive patterns of anti-MART-1 with those of HMB-45, we performed avidin-biotin immunoperoxidase testing o n nonmelanocytic neoplasms (AMLs, LAMs, CCSTs) known to express HMB-45 , Microwave pretreatment was necessary for anti-MART-1 staining on par affin-embedded material, Our results showed that all of the 10 cases o f AML were immunoreactive for both anti-MART-1 and HMB-45; that all of the 4 cases of LAM were positive for HMB-45, with 1 of the 4 reacting with anti-MART-1; and that 3 of the 4 cases of CCST expressed HMB-45, whereas 1 of the 4 was positive for anti-MART-1. Our findings lent ad ditional support to previous studies that proposed a relationship betw een AML, LAM, and CCST, Anti-MART-1 and HMB-45 share similar specifici ties for these nonnelanocytic tumors, but the former seems to be a les s sensitive marker for these lesions. In similar circumstances, anti-M ART-1 and HMB-45 are potentially useful clinical markers.