F. Sallusto et al., A flavonoid sulfate antigen activates human alpha beta CD8(+) Th2 lymphocytes in pollen allergy, EUR J IMMUN, 30(3), 2000, pp. 964-968
Cellular immune responses are initiated when T lymphocytes expressing alpha
beta TCR recognize peptide antigens bound to MHC molecules or, less freque
ntly, double-stranded glycolipid antigens bound to CD1 molecules. In the al
lergy to Parietaria judaica, human alpha beta CD8(+) Th2 lymphocytes react
to a non-peptide pollinic antigen presented by B cells. The environmental a
llergen was purified and identified as a new flavonoid pigment: 2'-O-sulfat
e, 6-O-beta D-glucuronopyranosyl, 2',5,6-trihydroxy-isoflavone. Its specifi
c recognition by alpha beta CD8(+) Th2 T cells (1) depends upon an MHC- and
CD1-independent presentation mediated by B cells, (2) is determined by the
flavonoid carbohydrate and sulfate groups and (3) leads to positive skin p
rick test in allergic patients. Hence, an unusual mode of aromatic sulfated
antigen recognition by alpha beta CD8(+) Th2 T lymphocytes might underlie
the cellular mediation of human allergy to plant allergens.