Figure 6.
ELISPOT fingerprinting of RP-HPLC-fractionated natural peptides extracted from LCL-derived HLA class II molecules. Naturally processed peptides were isolated from affinity-purified HLA–DR complexes prepared from 109 IP1-LCL cells and were fractionated by using RP-HPLC. Individual HPLC fractions were lyophilized, reconstituted in Hanks’ balanced salt solution and then tested for IFN-γ spot production by CD4+ T cells obtained from EBV-seropositive donor IP1 by ex vivo isolation from the blood (1.5 × 105 per well; □) or by three weekly stimulations with IP1-LCL freeze-thaw lysate-loaded mature DC (1.5 × 104 per well; ●). Autologous immature DC were used as APC. Each determination was done in duplicate. Spots developed after a culture period of 40 h were evaluated and presented as described in Fig. 3.