Comparison of CTL reactivity in the spleen and draining lymph nodes after immunization with peptides pulsed on dendritic cells or mixed with Freund’s incomplete adjuvant

Abstract

Objective: To compare CTL reactivity in the spleen and the draining lymph nodes (LN) from C57BL/6 mice after immunization with self and non-self peptides pulsed on autologous dendritic cells (DC) or mixed with Freund’s incomplete adjuvant (FIA). Methods: Peptides showing high to low binding affinities for H-2 K b/D b were emulsified in FIA or pulsed on bone marrow (BM)-derived DC and injected subcutaneously into C57BL/6 mice. Eight days later, the mice were sacrificed and cell suspensions were prepared from the spleen and draining LN. Splenocytes or LN cells were cultured for 5 days with irradiated syngeneic spleen cells (as APCs) pulsed with the appropriate peptide in vitro. 51 Cr -release assay using peptide pulsed target cells was used to detect CTL reactivity. Results: Both self and non-self peptides can induce specific CTL responses with the adjuvant FIA and DC. Peptide pulsed DC were found to be more effective than peptides mixed with FIA to induce specific CTL responses towards non-self peptides and can induce much stronger responses in the spleen than in the draining LN both for non-self and self peptides. Self peptides emulsified in FIA generated the strongest responses in the draining LN, whereas non-self peptides mixed with FIA generated the strongest response in the spleen. Conclusions: DC-based immunization with non-self and self peptides is more efficient than immunization based on peptides mixed with FIA. DC-based immunization focuses the CTL response towards the spleen. Immunization based on FIA focuses the response against self peptides towards the draining LN and non-self peptides towards the spleen.