Page 597 - Veterinary Immunology, 10th Edition

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FIG. 19.12 The species difference between the MHC class I
receptors on NK cells. Humans possess a single, nonfunctional
Ly49 gene. Thus they rely totally on KIR molecules, whereas mice
rely totally on Ly49 molecules for recognition of their MHC ligands.
Most domestic species resemble humans except for the horse that
resembles the mouse in its receptor usage.

Horses

Equine NK cells are activated by recombinant human IL-2 and are
active against human tumor cell targets. Horses have six
transcribed Ly49 genes but no transcribed KIR genes. Thus horse

NK cell receptors resemble those of rodents rather than those of the
other domestic mammals.

Cattle

NK cells constitute about 3.5% of blood lymphocytes in young
calves and about 2% in older cattle. They are found in highest

concentrations in the spleen, lymph nodes, and peripheral blood.
Bovine NK cells can kill human cancer cell targets as well as bovine
cells infected with parainfluenza-3, bovine leukemia virus (BLV), or

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