The 1-1-2 monoclonal antibody specifically recognizes the Qa-2 MHC class Ib antigen, which is expressed at higher levels on mature T lymphocytes than on B cells. Its expression is upregulated in the late stages of T-cell maturation. Qa-2 is a 40 kDa GPI-linked cell surface molecule encoded by the Q5, Q6, Q7, and/or Q9 genes of the H-2 complex. A 39 kDa soluble form results from alternative splicing of the transcript. Although Qa-2 is nonpolymorphic, its level of expression on both T and B lymphocytes varies among inbred mouse strains. High expressors include strains carrying the H-2[b] haplotype low expressors include H-2[d] strains, and H-2[k] strains are Qa-2-negative.
The antibody was conjugated to BD Horizon™ BUV805 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348 nm and an acceptor dye with an Em Max at 805 nm. BD Horizon Brilliant BUV805 can be excited by the ultraviolet laser (355 nm) and detected with a 820/60 filter and a 770LP.