CD28 CTLA-4 LIGANDS - THE GENE ENCODING CD86 (B70/B7.2) MAPS TO THE SAME REGION AS CD80 (B7/B7.1) GENE IN HUMAN-CHROMOSOME 3Q13-Q23/

CD86 (B70/B7.2) is an antigen of the immunoglobulin superfamily expres sed on monocytes, dendritic cells and activated B, T, and natural kill er cells. CD86 was recently identified as a second ligand for the T ce ll antigens CD28 and CTLA-4, and plays an important role in the co-sti mulation of T cells in a primary immune response. We report here the a ssignment of the CD86 gene to human chromosome 3 using Southern blot a nalysis on a panel of hamster X human somatic cell hybrid genomic DNA. Fluorescence hybridization in situ on metaphase chromosomes coupled w ith GTG banding (G-bands by trypsin using Giemsa staining) confirmed t his assignment and localized the CD86 gene to 3q13-q23 region. The CD8 6 gene is, therefore, located in the proximity of the CD80 (B7/B7.1) g ene, the first identified ligand for CD28 and CTLA-4, previously mappe d to chromosome 3q13.3-q21. Deletions, inversions and insertions of ch romosome 3q21-q26, as well as translocations of 3q21 with other chromo somes have been described in many cases of acute myeloid leukemia (AML ), acute nonlymphocytic leukemia (ANLL), chronic myeloid leukemia (CML ) and myelodisplastic syndromes (MDS), suggesting that this region con tains several genes involved in the leukemic process.