Lsp1-/- DENDRITIC CELLS EXHIBIT DELAYED ANTIGEN DEGRADATION DUE TO AN IMPAIRED UPTAKE

NICOLAS DHO; MARIA MERCEDES PASCUAL; M CRISTINA PISTORESI; BELKYS MALETTO; M INES CRESPO; GABRIEL MORON

Congreso; LXX REUNIÓN SAI; 2022

Leukocyte-specific protein 1 (LSP1) is a 52kDa cytoplasmic F-actin binding phosphoprotein expressed in all human and murine leukocytes and endothelial cells. LSP1 is an important regulator of actin cytoskeleton remodelling. We have previously shown that Lsp1-/- dendritic cells (DCs) have a defective antigen presentation to CD4+ T cells compared to DCs from wild type (WT) mice and that MHC class II dynamics is similar between Lsp1+/+ and Lsp1-/- DCs. We thus studied whether this defective antigen presentation in Lsp1-/- DCs is due to either an alteration in the uptake or in the processing of Ag, using DCs in vitro derived from bone marrow precursors with Flt3-L. For antigen degradation, DCs were co-cultured with OVA-DQ (which fluoresces after being degraded by proteases) for 15min, 1, 2, 3 and 4h. After these times DCs were fixed, permeabilizated and stained with anti-CD107a, a marker of lysosomes, and analyzed by in cell imaging system (INCell Analyzer 2500HS). We found that Lsp1-/- DCs showed significant lower levels of OVA-DQ degradation (p