Lsp1-/- DENDRITIC CELLS HAVE SIMILAR MHC II KINETICS DESPITE THEIR IMPAIRED ABILITY TO PRESENT ANTIGENS TO CD4+ LYMPHOCYTES.

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

virtual

Congreso; LXIX REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2021

SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI)

Leukocyte-specific protein 1 (LSP1) is a 52kDa cytoplasmic F-actinbinding phosphoprotein expressed in all human and murineleukocytes and endothelial cells. LSP1 is an important regulatorof actin cytoskeleton remodelling. We have previously shown thatLsp1-/- dendritic cells (DCs) have a defective antigen presentationto CD4+ T cells compared to DCs from wild type (WT) mice. In orderto study whether defective antigen presentation in Lsp1-/- miceis due to alteration in MHC class II dynamics, we evaluated I-Abkinetics expression on cell surface and intracellulary in Lsp1-/- DCsupon activation with CpG-ODN. DCs were in vitro derived from bone marrow precursors with Flt3-L and stimulated with CpG-ODN 1826,at different times (1-2-3-4-8-12 and 18h) they were collected andstained with anti-I-Ab antibody (Ab) either permeabilized or not,to measure total or cell surface content of I-Ab and analyzed byflow cytometry. We found that total and cell surface I-Ab moleculesincreases in Lsp1-/- DCs upon stimulation similar than DCs fromLsp1+/+ mice, with a peak in both cases at 3h. Intracellular contentof I- Ab increased more than cell surface expression in bothgroups and remained high for at least 18h. Analyzing the kinetics ofpeptide-I-Ab complexes on DC surface by incubating DCs with theEa52-68 peptide (which binds to I-Ab) and then labeling them withY-Ae Ab (which recognizes I-Ab-Ea52-68 complex) by flow cytometry,we observed that these complexes remained stable up to 24hafter on surface in Lsp1-/- and Lsp1+/+ stimulated DCs at similarlevels. These results suggests that the altered antigen presentationin Lsp1-/- DCs could be related to other steps in Ag processing andnot to MHC II dynamics.