Page 598 - Veterinary Immunology, 10th Edition

bovine herpesvirus type 1 (BHV-1). They generate resistance to
VetBooks.ir mycobacteria by preventing its replication within macrophages.

They play a role in resistance to the protozoan parasite Neospora
caninum by producing IFN-γ that kills infected cells. Three

subpopulations have been described. For example, most bovine NK
cells express both CD2 and NCR1, but subpopulations may be CD2
or NCR negative. Other NK cell surface molecules include CD16,
perforins, CD5, CD94, WC1, MHC class II, and asialo-GM . (GM is
1 1
a ganglioside–a glycolipid molecule composed of a fatty ceramide
residue buried in the lipid bilayer of a cell with at least three sugar
groups projecting into the extracellular fluid. One of these is

normally a sialic acid group. This is lacking in asialo-GM .) Cattle
1
also have some circulating NCR1-positive T cells.

Cattle NK use KIR proteins as MHC class I receptors. Cattle have
at least six KIR genes, some of whose products are inhibitory,
whereas others are activating. They also have variable haplotype
composition. Cattle NK cells also express NKG2D. Cattle probably

have four MIC genes. One gene is consistently present, whereas the
presence of the other three is variable. They possess one Ly49 gene
with three alleles, so cattle are the only species known to have both
polymorphic Ly49 genes and KIR genes. Cattle also have at least 16

LILRs, of which seven are likely inhibitory, four are activating and
five are soluble. Thus overall, cattle NK cells are highly
heterogeneous and differentially express many different receptors
for MHC class I.

Cattle NK cells are activated by IL-2, IL-12, IL-15, IFN-α, and
IFN-γ. Activation by IL-2 enables them to express CD25 and CD8
and lyse tumor cell lines. If activated by IL-12 and IL-15, they
express increased amounts of granulysin, IFN-γ, and perforin, and

can kill both human tumor cells and bacille Calmette-Guérin (BCG)-
infected macrophages. Cattle also produce NK-lysin and, uniquely,
have four functional NK-lysin genes (as opposed to one in other
mammals). Three (NK1, NK2A, and NK2B) are predominantly
expressed in the Peyer's patches, while one (NK2C) is found

exclusively in the lungs.

Sheep

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+
Sheep have CD16 , CD14 NK cells in their blood. More than 80% of

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