Double-immunofluorescence staining of PBMC from an HCL patient. Cell smears were fixed in acetone and incubated with a Cy3-labeled mouse anti-CD11c MoAb and a mouse anti-bFGF MoAb followed by the TS amplification system (see Materials and Methods). Green (A, anti-bFGF) and red (B, anti-CD11c) fluorescent signals from the same field were recorded sequentially. Experiments using isotype control antibodies or PBMC from an HD were negative (not shown).