M. Feilihariri et al., FUNCTIONAL CONSEQUENCES OF THE BINDING OF MHC CLASS II-DERIVED PEPTIDES TO MHC CLASS-II, International immunology, 8(12), 1996, pp. 1857-1865
Three MHC class II-derived synthetic peptides (I-A(beta)(g7)1-16, I-A(
beta)(g7)52-77 and I-A(alpha)(g7)63-82YC) were analyzed for their abil
ity to bind to syngeneic and allogeneic MHC class II molecules using a
whole cell, competitive peptide binding assay, These studies demonstr
ated that the A(beta)(g7)1-16 peptide was able to specifically bind to
syngeneic as well as to four allogeneic MHC class II molecules. The A
(alpha)(g7)63-82YC peptide bound to self MHC class II molecules with a
lower relative affinity and was able to bind to three out of the four
allogeneic cells tested, The binding of the three I-A(g7)-derived pep
tides to the self MHC class II was functionally significant, The A(bet
a)(g7)1-16 and A(beta)(g7)52-77 peptides inhibited the proliferation o
f a heat shock protein 60 peptide-specific T(h)1 clone by MHC blockade
, Interestingly, the A(alpha)(g7)63-82YC peptide appeared to interact
directly with T cells as pretreatment of the T(h)1 clone with this pep
tide resulted in inhibition of antigen-induced proliferation. This phe
nomenon was analyzed in more detail and it was found that this peptide
could behave as a partial agonist. Incubation of T cells with the A(a
lpha)(g7)63-82YC peptide resulted in up-regulation of IL-2R alpha chai
n expression and induction of IFN-gamma secretion. In addition T cells
pretreated with this peptide were rendered hyporesponsive to further
antigenic stimulation. Thus, a peptide derived from MHC class II may b
e used in an immunoregulatory capacity.