Bovine polymorphonuclear cells passively acquire membrane lipids and integral membrane proteins from apoptotic and necrotic cells

Abstract

Immune cells can acquire membrane fragments and integral membrane proteins from dead and dying cells or in the case of immature dendritic cells, from live cells. While investigating the possibility that bovine polymorphonuclear cells (PMNs) might present antigen, coculture assays confirmed that integral membrane proteins were transferred rapidly and efficiently to bovine PMNs from a variety of apoptotic and necrotic cells. Specifically, we observed that PMNs rapidly acquired proteins such as major histocompatibility complex (MHC) class II and CD3 from a variety of syngeneic, allogeneic, and xenogeneic cell types. Such acquisition occurred within 40 min of PMN coculture with isolated peripheral blood mononuclear cells, and this acquisition occurred with equal efficiency at 4 degrees C and 37 degrees C. The transfer of murine MHC class II to bovine PMNs precluded the possibility of endogenous protein expression. We also demonstrated the transfer of fluorescently labeled plasma membrane lipids and biotinylated integral membrane proteins. Collectively, these observations support the hypothesis that membrane protein transfer was mediated by the fusion of membrane fragments or microvesicles with the PMN plasma membrane and not by phagocytosis of cell fragments. These observations indicate that phenotypic studies of PMNs must consider circumstances whereby PMNs may passively acquire membrane lipids and a variety of integral membrane proteins from dead or dying cells.

Within Peripheral Blood Mononuclear Cells, Antibody-Dependent Cellular Cytotoxicity of Rituximab-Opsonized Daudi cells Is Promoted by NK Cells and Inhibited by Monocytes due to Shaving

“…In separate experiments with neutrophils isolated from the blood of two different donors, we found that between 50 and 75% of the bound RTX was removed from Al488 RTX-opsonized Daudi cells. This result is in agreement with the findings of Whale et al which revealed that neutrophils can indeed remove ligands from other cells (54).…”

Capture of plasma membrane fragments from target cells by trogocytosis requires signaling in T cells but not in B cells

“…36 Our study provides a foundation from which to explore the mechanism(s) of trogocytosis further. Because trogocytosis is performed not only by lymphocytes but also by most hematopoietic cells [9][10][11][12][13] and is proposed to have important physiopathologic 6,17 and possibly therapeutic 12 consequences, exploring the mechanisms of trogocytosis is of a crucial importance and may open new ways to manipulate the immune response.…”

“…6 Initially, using well-characterized murine models of antigen-specific lymphocytes, we made this observation in CD8 ϩ CTLs but, later, we showed that CD4 ϩ T cells and B cells also perform trogocytosis (ie, they acquire membrane-anchored antigen in fragments of membrane). 7,8 Trogocytosis has since also been reported for most other hematopoietic cells including natural killer (NK) cells (see RodaNavarro and Reyburn 9 for a review), dendritic cells, 10 monocytes, 11,12 and neutrophils, 13 indicating that antigen recognition by antigen receptors is not the only molecular trigger for trogocytosis. Worthy of note, activated but not resting CD4 ϩ and CD8 ϩ T cells were shown to acquire membrane patches from target cells in the absence of antigen and independently of the TCR.…”

Divergent Immune Responses to Mycobacterium avium subsp. paratuberculosis Infection Correlate with Kinome Responses at the Site of Intestinal Infection

“…paratuberculosis infection and 1 day prior to euthanizing. PBMCs were isolated following a previously described protocol (20). Briefly, blood was centrifuged at 1,400 ϫ g for 20 min at room temperature before collecting the buffy coat and resuspending cells in 35 ml Ca 2ϩ -and Mg 2ϩ -free PBS (PBSA) containing 0.1% EDTA.…”