S. Maier et al., Implications of HLA-E allele expression and different HLA-E ligand diversity for the regulation of NK cells, HUMAN IMMUN, 61(11), 2000, pp. 1059-1065
The interaction of HLA-E: with CD94/NKG2A is dependant on the binding of HL
A class I signal sequence derived peptides to HLA-E. In the caucasoid popul
ation two HLA-E alleles are observed at equal frequencies. I-Ic re are stud
y the functional differences between the two HLA-E molecules with regard to
cell surface expression, peptide binding, and potential to inhibit lytic a
ctivity of a CD94/NKG2A(+) NK cell line. In contrast to the HLA-E-R allele,
the HLA-E-G allele shows considerable cell surface expression even in the
absence of endogenous HLA class I signal sequence derived HLA-E ligands. Ei
ghteen HLA-E allele/HLA-E ligand combinations were analyzed. No correlation
between cell surface expression of HLA-E and NK cell inhibition was observ
ed. The peptides present in the signal sequences of HLA-B15, -Cw0402, and -
Cw7 bound to both HLA-E alleles but did not lead to an inhibition of NK cel
l lysis. In our experimental system the peptides A2 and G were not effectiv
e with regard to NK cell inhibition when bound to the HLA-E-R allele. These
results may be of functional significance particularly in the placenta whe
re the only HLA-E ligands are derived from HLA-G and -C. (C) American Socie
ty for Histocompatibility and Immunogenetics, 2000. Published by Elsevier S
cience Inc.