The 4D11 antibody specifically recognizes Ly-49G2 (also known as LGL-1), an inhibitory receptor which is expressed on subsets of natural killer (NK) cells and DX5-positive T lymphocytes (NK-T cells) in all strains tested (e.g., AKR/N, BALB/c, C3H/HeJ, C57BL/6, CBA/J, DBA/2, SJL, 129) and on a population of memory CD8+ T lymphocytes in C57BL/6 mice. Cross-reaction of 4D11 antibody to Ly-49A[B6], Ly-49A[BALB], and Ly-49T[129/J] inhibitory receptors and Ly-49L[CBA/J] activating receptor has been reported. The proportion of NK-T cells expressing Ly-49A and Ly-49G2 is higher (2-5 fold) in thymus than in liver (immature and mature NK-T cells, respectively), and there is evidence that down-regulation of Ly-49 receptor expression is necessary for normal NK-T-cell development to occur. Most NK cells express a single allele of Ly-49A and/or Ly-49G2, although occasionally they may express more than one allele. The Ly-49 family of NK-cell receptors, members of the C-type lectin superfamily, are disulfide-linked type-II transmembrane protein homodimers with extracellular carbohydrate-recognition domains, which bind to MHC class I alloantigens. The Ly-49 family members are expressed independently, such that an individual NK or T cell may display more than one class of Ly-49 receptor homodimers. Binding of Ly-49G[B6]-expressing transfectants to H-2Dd+/H-2Ld+ ConA blasts has been demonstrated, and H-2D[d]-expressing target cells inhibit the lytic activity of Ly-49G2-expressing NK cells. The levels of the Ly-49 inhibitory receptors are down-regulated by their ligands in vivo, and the various levels of expression of a Ly-49 inhibitory receptor may affect the specificity of NK cells. Ly-49G2[+] NK cells are able to lyse target tumor cells expressing H-2[a] and H-2[b] MHC class I antigens in vitro, and they mediate allogeneic and hybrid resistance to H-2[b] bone marrow transplantation. The Ly-49A[BALB] and Ly-49A[B6] alloantigens bind to MHC class I antigens of the d and k haplotypes, and Ly-49A[+] IL-2-activated NK cells are unable to lyse target cells expressing H-2[d] and H-2[k]. In vitro studies suggest that the Ly-49G2 and Ly-49A receptors mediate negative regulation of NK-cell cytolytic activity via tyrosine phosphorylation of their ITIMs (Immunoreceptor Tyrosine-based Inhibitory Motifs). Ly-49T[129/J] has a unique ITIM sequence, and Ly-49T-transfected 293T (human kidney epithelial) cells do not bind soluble tetramers of any tested H-2 alloantigen (D[b], D[d], D[k], K[b], K[d], K[k], L[d]).
The antibody was conjugated to BD Horizon BUV615 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome with an Ex Max near 350 nm and an Em Max near 615 nm. BD Horizon Brilliant BUV615 can be excited by the ultraviolet laser (355 nm) and detected with a 610/20 filter and a 595 nm LP. Due to the excitation of the acceptor dye by the blue/yellow-green laser line, there may be significant spillover into channels detecting PE-CF594 like emissions (eg, 610/20-nm filter).