Rabbit Anti-Human CD6 (a.a. 18-350) Polyclonal antibody

The immune system of swine is unique in that the expression of CD4 and CD8 antigens defines four subpopulations of resting extrathymic T lymphocytes. Beyond phenotypic differences to other species, porcine T lymphocytes, particularly when derived from infected animals, are known to show high non-specific cytolytic in vitro activity. Here we describe the putative porcine CD6 antigen (workshop CD6; wCD6) which enables a phenotypic separation of T lymphocytes responsible for major histocompatibility complex (MHC)-restricted and non-MHC-restricted cytotoxicity. The putative porcine CD6 analogue, wCD6, a protein with a molecular mass of 110 000, shows high specificity for T lymphocytes and is neither expressed on B lymphocytes nor on cells of the myeloid lineage. In the extrathymic T-lymphocyte compartment wCD6 characterizes two T-lymphocyte fractions: wCD6(+) T lymphocytes including both CD4(+) T-helper cell subpopulations (CD4(+)CD8(-) and CD3(+)CD8(+)) and within the CD4(-)CD8(+) fraction cells with high CD8 antigen density. In contrast the CD4(-)CD8(-) gamma/delta T-cell receptor (TCR) subset and CD4(-)CD8(+) cells with low CD8 antigen density are included in the wCD6(-) T-lymphocyte fraction. Functional studies with separated wCD6 fractions revealed that the wCD6(-) cells can be characterized by spontaneous and non-MHC restricted cytolytic activity, whereas the wCD6(+) T lymphocytes are responsible for MHC-restricted T-cell functions. Thus, the porcine wCD6 is an important antigen to discriminate between MHC-restricted and non-MHC-restricted cytotoxicity.

A(H1N1)pdm09 influenza A viruses predominated in the 2013-2014 USA influenza season, and although most of these viruses remain sensitive to Food and Drug Administration-approved neuraminidase (NA) inhibitors, alternative therapies are needed. Here we show that monoclonal antibody CD6, selected for binding to the NA of the prototypic A(H1N1) pdm09 virus, A/California/07/2009, protects mice against lethal virus challenge. The crystal structure of NA in complex with CD6 Fab reveals a unique epitope, where the heavy-chain complementarity determining regions (HCDRs) 1 and 2 bind one NA monomer, the light-chain CDR2 binds the neighbouring monomer, whereas HCDR3 interacts with both monomers. This 30-amino-acid epitope spans the lateral face of an NA dimer and is conserved among circulating A(H1N1) pdm09 viruses. These results suggest that the large, lateral CD6 epitope may be an effective target of antibodies selected for development as therapeutic agents against circulating H1N1 influenza viruses.