POOR CYTOTOXIC RESPONSE IN LEUKOCYTE SPECIFIC PROTEIN-1 DEFICIENT MICE IS ASSOCIATED WITH A REDUCED CROSS-PRESENTATION BY CD8+ DCS

RACHEL ACLAND; ESTEFANÍA ZACCA; MARÍA C. PISTORESI-PALENCIA; BELKYS MALETTO; G MORON

Mar del Plata

Congreso; LXII Reunión de la Sociedad Argentina de Inmunología. Mar del Plata; 2014

Sociedad Argentina de Inmunología

The leukocyte-specific protein 1 (LSP1), is a 52-kDa cytoplasmic F-actin binding phosphoprotein expressed in leukocytes and endothelial cells that regulates cytoskeleton thus cell motility and polarization. It has been reported that human and murine LSP1-/- dendritic cells (DCs), infected with HIV show decreased proteasome degradation and altered intracellular trafficking of virus. This unexpected finding suggests a putative role of LSP1 in antigen cross-presentation in DCs. To investigate this hypothesis, we measured the ability of LSP1-/- DCs pulsed with an exogenous antigen (ovalbumin, OVA) plus polyuridilic acid (PU, a TLR7 ligand) to induce cytotoxic response. We found that wild-type (WT) mice that received the OVA/PU-pulsed LSP1-/- DCs had a lower CTL response (30±8% of specific lysis) compared to mice transferred with OVA/PU-pulsed WT DCs (64±3%, p<0.01). WT and LSP1- /- splenocytes or BMDCs showed no differences in OVA uptake. Using a H2-Kb-restricted OVA257-264 epitope CD8+ T cell hybridoma, we found that LSP1-/- CD8a+ DCs have a lower ability to activate CD8 T cells when pulsed with whole OVA in comparison to WT CD8a+ DCs, but the same ability when DCs are pulsed with the peptide OVA256-264, revealing a role for LSP1 in antigen crosspresentation. We have previously showed no differences in DC and other leukocyte content in the spleen of WT vs LSP1-/- mice as well as a similar ability in DCs to mature upon TLR7 stimulation. Furthermore, we analyzed the ability of LSP1-/- DCs to migrate to lymphoid tissues. By flow cytometry we observed a delayed DC arrival to draining lymph nodes after subcutaneous injection of LSP1-/-DCs into wt mice, compared to injected WT DCs (p<0,001 24h, ns 48hs post injection) showing that LSP1-/- DCs have an impaired migratory activity compared to WT mice. In conclusion, LSP1 is involved in antigen cross-presentation and cell migration in DCs in a way that its lack results in decreased cytotoxic responses.