LSP1-/- DENDRITIC CELLS HAVE SIMILAR MHC II KINETICS DESPITE THEIR IMPAIRED ABILITY TO PRESENT ANTIGENS TO CD4+ LYMPHOCYTES

NICOLAS DANIEL DHO; BELKYS A. MALETTO; MARÍA INÉS CRESPO; MERCEDES PASCUAL; G MORON

virtual

Congreso; LXIX REUNIÓN SAI; 2021

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 havepreviously shown that Lsp1-/- dendritic cells (DCs) have a defective antigen presentation to CD4+ T cells compared to DCs from wild type (WT) mice. In order to study whether defective antigen presentation in Lsp1-/- mice is due to alteration in MHC class II dynamics, we evaluated I-Ab kinetics expression on cell surface and intracellulary in Lsp1-/- DCs upon activation with CpG-ODN. DCs were in vitroderived from bone marrow precursors with Flt3-L and stimulated with CpG-ODN1826, at different times (1-2-3-4-8-12 and 18h) they were collected and stained with anti-I-Ab antibody (Ab) either permeabilized or not, to measure total or cell surface content of I-Ab and analyzed by flow cytometry. We found that total and cell surface I-Ab molecules increases in Lsp1-/- DCs upon stimulation similar thanDCs from Lsp1+/+ mice, with a peak in both cases at 3h. Intracellular content of IAbincreased more than cell surface expression in both groups and remained high for at least 18h. Analyzing the kinetics of peptide-I-Ab complexes on DC surface by incubating DCs with the Ea52-68 peptide (which binds to I-Ab) and then labeling them with Y-Ae Ab (which recognizes I-Ab-Ea52-68 complex) by flow cytometry, weobserved that these complexes remained stable up to 24h after on surface inLsp1-/- and Lsp1+/+ stimulated DCs at similar levels. These results suggests that the altered antigen presentation in Lsp1-/- DCs could be related to other steps in Ag processing and not to MHC II dynamics.