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Sensitive visualization of peptide presentation in vitro and ex vivo
Désirée Kunkel1, Dennis Kirchhoff, Rudolf Volkmer-Engert
1Deutsches Rheuma-Forschungszentrum Berlin, Germany.
Background:
The presentation of antigenic peptides to specific T cells is one of the key events for the induction of a T-cell-dependent immune response. The nature of the antigen-presenting cells which present distinct peptides has been difficult to analyze so far due to the low number of peptides presented in vivo by a single antigen-presenting cell.
Methods:
We have used magnetofluorescent liposomes to identify and characterize antigen-presenting cells according to presentation of a hapten-labeled antigenic peptide in vitro and ex vivo.
Results:
Magnetofluorescent liposomes allowed the identification and isolation of antigen-presenting cells according to the presentation of less than 100 peptides per cell, the physiological threshold for activation of specific T cells. Ex vivo, we could demonstrate peptide presentation by B lymphocytes and dendritic cells already 1 h after intravenous peptide injection; this rapidly declined to background level after 12-24 h.
Conclusions:
The sensitive visualization of peptide presentation allows the phenotypical and functional characterization of those antigen-presenting cells which present specific peptides at physiological relevant quantities. This technology will help to characterize the antigen-presenting cells (APC) which are responsible for the induction of distinct immune reactions in vivo, e.g., the generation of tolerance or immunity.