Qa-1b

Qa-1b is a MHC class I molecule and is the functional homolog of HLA-E in humans. Qa-1b is characterised by its limited polymorphisms and small peptide repertoire. Qa-1b binds to peptides derived from signal peptides of MHC class Ia molecule and interact with the CD94/NKG2 receptors on natural killer cells. The Qa-1b-peptide complex signals natural killer cells not to engage in cell lysis. Despite its homology with HLA-E, it seems that Qa-1b evolved a similar function to HLA-E coincidentally.

Surface antigens

Major histocompatibility complex/
Human leukocyte antigen

MHC class I	HLA-A HLA-B HLA-C HLA-E HLA-F HLA-G

MHC class II	HLA-DM α β HLA-DO α β HLA-DP α1 β1 HLA-DQ α1 α2 β1 β2 β3 HLA-DR α β1 β3 β4 β5 Minor histocompatibility antigen

Other

Index of the immune system

Description	Physiology cells autoantigens autoantibodies complement surface antigens IG receptors

Disease	Allergies Immunodeficiency Immunoproliferative immunoglobulin disorders Hypersensitivity and autoimmune disorders Neoplasms and cancer

Treatment	Procedures Drugs antihistamines immunostimulants immunosuppressants monoclonal antibodies