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

NICOLÁS DANIEL DHO; MARÍA MERCEDES PASCUAL; CRESPO, MARÍA INÉS; MARÍA CRISTINA PISTORESI; MALETTO, BELKYS A.; MORON GABRIEL

Congreso; REUNIÓN DE SOCIEDADES DE BIOCIENCIAS 2021; 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 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. 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 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 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 than DCs from Lsp1+/+ mice, with a peak in both cases at 3h. Intracellular content of IAb increased 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 labelingthem with Y-Ae Ab (which recognizes I-Ab-Ea52-68 complex) by flow cytometry, we observed that these complexes remained stable up to 24h after on surface in Lsp1-/- 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.