Binding of Fab antibodies to APCs. RMAS-HHD or JY cells were
loaded with the indicated HLA-A2-restricted peptides. Peptide-loaded
cells were then incubated with the specific soluble purified Fab
antibodies as shown. Detection of binding was with FITC-labeled
anti-human Fab. (A) RMAS-HHD cells loaded with the
G9-209 peptide and control unloaded cells were stained with the
anti-HLA-A2 antibody BB7.2 to demonstrate the
stabilization/expression of HLA-A2 complexes on the surface of
peptide-loaded but not on peptide-unloaded cells. (B)
RMAS-HHD cells were loaded with the G9-154 (marked) and control G9-280
peptides or control unloaded cells. Cells were stained with the
G9-154-specific Fab G2D12. (C) RMAS-HHD cells were
loaded with peptides G9-209-specific (marked) and G9-154 (control).
Loaded and unloaded cells were stained with the G9-209-specific Fab
1A7. (D) RMAS-HHD cells were loaded with G9-280-specific
(marked) and G9-209 (contol) peptides. Loaded and unloaded cells were
stained with the G9-280-specific Fab 2F1. (E) RMAS-HHD
cells were loaded with peptide G9-154 and incubated with Fabs G2D12
(marked), 1A7, and 2F1 specific for G9-154, G9-209, and G9-280,
respectively. (F) JY cells were loaded with peptides
G9-209 and stained with anti-HLA-A2 BB7.2 antibody. Controls are cells
incubated with secondary anti-mouse-FITC antibody. (G)
JY cells were loaded with peptides G9-154 (marked), G9-209, G9-280, or
unloaded and then reacted with the G9-154/HLA-A-specific Fab G2D12.
(H) JY cells were loaded with peptides G9-209 (marked),
G9-154, G9-280, or unloaded and then reacted with the
G9-209/HLA-A-specific Fab 1A7. (I) JY cells were
loaded with peptides G9-280 (marked), G9-154, G9-209, or unloaded and
then reacted with the G9-280/HLA-A-specific Fab 2F1.
(J) JY cells were loaded with the peptide G9-154 and
incubated with Fabs G2D12 (marked), 1A7, and 2F1 specific for G9-154,
G9-209, and G9-280 in complex with HLA-A2, respectively. Control
unloaded cells are represented by black traces.