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The CD16(+) (FcgammaRIII(+)) subset of human monocytes preferentially becomes migratory dendritic cells in a model tissue setting.

Randolph GJ, Sanchez-Schmitz G, Liebman RM, Schäkel K - J. Exp. Med. (2002)

Bottom Line: These DCs migrate across endothelium in the ablumenal-to-lumenal direction (reverse transmigration), reminiscent of the migration into lymphatic vessels.CD16 was not functionally required for reverse transmigration, but promoted cell survival when yeast particles (zymosan) were present as a maturation stimulus in the subendothelial matrix.We propose that CD16(+) monocytes may contribute significantly to precursors for DCs that transiently survey tissues and migrate to lymph nodes via afferent lymphatic vessels.

View Article: PubMed Central - PubMed

Affiliation: The Carl C. Icahn Institute for Gene Therapy and Molecular Medicine, Mt. Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA. gwendalyn.randolph@mssm.edu

ABSTRACT
Much remains to be learned about the physiologic events that promote monocytes to become lymph-homing dendritic cells (DCs). In a model of transendothelial trafficking, some monocytes become DCs in response to endogenous signals. These DCs migrate across endothelium in the ablumenal-to-lumenal direction (reverse transmigration), reminiscent of the migration into lymphatic vessels. Here we show that the subpopulation of monocytes that expresses CD16 (Fcgamma receptor III) is predisposed to become migratory DCs. The vast majority of cells derived from CD16(+) monocytes reverse transmigrated, and their presence was associated with migratory cells expressing high levels of CD86 and human histocompatibility leukocyte antigen (HLA)-DR, and robust capacity to induce allogeneic T cell proliferation. A minority of CD16(-) monocytes reverse transmigrated, and these cells stimulated T cell proliferation less efficiently. CD16 was not functionally required for reverse transmigration, but promoted cell survival when yeast particles (zymosan) were present as a maturation stimulus in the subendothelial matrix. The cell surface phenotype and migratory characteristics of CD16(+) monocytes were inducible in CD16(-) monocytes by preincubation with TGFbeta1. We propose that CD16(+) monocytes may contribute significantly to precursors for DCs that transiently survey tissues and migrate to lymph nodes via afferent lymphatic vessels.

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Distribution of CD16+ monocyte-derived cells after coculture with endothelial cells grown on collagen. (A) Expression of CD16 was monitored in monocyte/endothelial cocultures at 48 h, when the majority of cells that will reverse transmigrate have done so. Assessments were made in reverse transmigrated (R/T, thin-lined profile) and subendothelial (S/E, bolded line profile) monocyte-derived cells from cultures that received no activation stimuli such as exogenous cytokines or phagocytic particles. Dotted line demarcates the staining intensity of cells incubated with isotype-matched mAbs to an irrelevant antigen. Filled profile represents the expression of CD16 in freshly isolated monocytes. (B) In other cultures, zymosan was included in the collagen to promote DC maturation. In some unstimulated endothelial cultures, the whole fraction of PBMCs (C) or CD16+ monocytes sorted using flow cytometry (D), were labeled with CFSE. Transendothelial migration into the collagen and subsequent reverse transmigration was evaluated to assess the distribution of CFSE+ cells. CFSE-labeled CD16+ monocytes were remixed with CD16− PBMCs so that CD16+ CFSE+ cells represented 15% of the total population (D).
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fig3: Distribution of CD16+ monocyte-derived cells after coculture with endothelial cells grown on collagen. (A) Expression of CD16 was monitored in monocyte/endothelial cocultures at 48 h, when the majority of cells that will reverse transmigrate have done so. Assessments were made in reverse transmigrated (R/T, thin-lined profile) and subendothelial (S/E, bolded line profile) monocyte-derived cells from cultures that received no activation stimuli such as exogenous cytokines or phagocytic particles. Dotted line demarcates the staining intensity of cells incubated with isotype-matched mAbs to an irrelevant antigen. Filled profile represents the expression of CD16 in freshly isolated monocytes. (B) In other cultures, zymosan was included in the collagen to promote DC maturation. In some unstimulated endothelial cultures, the whole fraction of PBMCs (C) or CD16+ monocytes sorted using flow cytometry (D), were labeled with CFSE. Transendothelial migration into the collagen and subsequent reverse transmigration was evaluated to assess the distribution of CFSE+ cells. CFSE-labeled CD16+ monocytes were remixed with CD16− PBMCs so that CD16+ CFSE+ cells represented 15% of the total population (D).

Mentions: Next we followed the expression of CD16 by monocyte-derived cells present in endothelial/collagen cultures for 48 h, during which time nearly half of the originally transmigrated cells retraverse the endothelium in the ablumenal-to-lumenal direction (reverse transmigration). In endothelial cultures receiving no exogenous stimulus such that the reverse-transmigrated population fails to differentiate into fully mature DCs, most or all of the reverse-transmigrated cells expressed CD16 (Fig. 3 A), and as many as 20% of these cells were M-DC8+ (unpublished data). However, the cell surface density of CD16 declined by about half during the 1.5 h incubation when monocytes entered the subendothelial collagen (unpublished data), relative to the level expressed in blood. This reduced level of CD16 was maintained throughout the culture period (Fig. 3, compare level of CD16 in blood monocyte to that expressed by reverse-transmigrated cells). Overt activation of the cultures with proinflammatory cytokines (unpublished data) or inclusion of zymosan in the collagen promoted complete loss of CD16 in the reverse-transmigrated population (Fig. 3 B), consistent with its documented downregulation during maturation of DCs.


The CD16(+) (FcgammaRIII(+)) subset of human monocytes preferentially becomes migratory dendritic cells in a model tissue setting.

Randolph GJ, Sanchez-Schmitz G, Liebman RM, Schäkel K - J. Exp. Med. (2002)

Distribution of CD16+ monocyte-derived cells after coculture with endothelial cells grown on collagen. (A) Expression of CD16 was monitored in monocyte/endothelial cocultures at 48 h, when the majority of cells that will reverse transmigrate have done so. Assessments were made in reverse transmigrated (R/T, thin-lined profile) and subendothelial (S/E, bolded line profile) monocyte-derived cells from cultures that received no activation stimuli such as exogenous cytokines or phagocytic particles. Dotted line demarcates the staining intensity of cells incubated with isotype-matched mAbs to an irrelevant antigen. Filled profile represents the expression of CD16 in freshly isolated monocytes. (B) In other cultures, zymosan was included in the collagen to promote DC maturation. In some unstimulated endothelial cultures, the whole fraction of PBMCs (C) or CD16+ monocytes sorted using flow cytometry (D), were labeled with CFSE. Transendothelial migration into the collagen and subsequent reverse transmigration was evaluated to assess the distribution of CFSE+ cells. CFSE-labeled CD16+ monocytes were remixed with CD16− PBMCs so that CD16+ CFSE+ cells represented 15% of the total population (D).
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Related In: Results  -  Collection

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fig3: Distribution of CD16+ monocyte-derived cells after coculture with endothelial cells grown on collagen. (A) Expression of CD16 was monitored in monocyte/endothelial cocultures at 48 h, when the majority of cells that will reverse transmigrate have done so. Assessments were made in reverse transmigrated (R/T, thin-lined profile) and subendothelial (S/E, bolded line profile) monocyte-derived cells from cultures that received no activation stimuli such as exogenous cytokines or phagocytic particles. Dotted line demarcates the staining intensity of cells incubated with isotype-matched mAbs to an irrelevant antigen. Filled profile represents the expression of CD16 in freshly isolated monocytes. (B) In other cultures, zymosan was included in the collagen to promote DC maturation. In some unstimulated endothelial cultures, the whole fraction of PBMCs (C) or CD16+ monocytes sorted using flow cytometry (D), were labeled with CFSE. Transendothelial migration into the collagen and subsequent reverse transmigration was evaluated to assess the distribution of CFSE+ cells. CFSE-labeled CD16+ monocytes were remixed with CD16− PBMCs so that CD16+ CFSE+ cells represented 15% of the total population (D).
Mentions: Next we followed the expression of CD16 by monocyte-derived cells present in endothelial/collagen cultures for 48 h, during which time nearly half of the originally transmigrated cells retraverse the endothelium in the ablumenal-to-lumenal direction (reverse transmigration). In endothelial cultures receiving no exogenous stimulus such that the reverse-transmigrated population fails to differentiate into fully mature DCs, most or all of the reverse-transmigrated cells expressed CD16 (Fig. 3 A), and as many as 20% of these cells were M-DC8+ (unpublished data). However, the cell surface density of CD16 declined by about half during the 1.5 h incubation when monocytes entered the subendothelial collagen (unpublished data), relative to the level expressed in blood. This reduced level of CD16 was maintained throughout the culture period (Fig. 3, compare level of CD16 in blood monocyte to that expressed by reverse-transmigrated cells). Overt activation of the cultures with proinflammatory cytokines (unpublished data) or inclusion of zymosan in the collagen promoted complete loss of CD16 in the reverse-transmigrated population (Fig. 3 B), consistent with its documented downregulation during maturation of DCs.

Bottom Line: These DCs migrate across endothelium in the ablumenal-to-lumenal direction (reverse transmigration), reminiscent of the migration into lymphatic vessels.CD16 was not functionally required for reverse transmigration, but promoted cell survival when yeast particles (zymosan) were present as a maturation stimulus in the subendothelial matrix.We propose that CD16(+) monocytes may contribute significantly to precursors for DCs that transiently survey tissues and migrate to lymph nodes via afferent lymphatic vessels.

View Article: PubMed Central - PubMed

Affiliation: The Carl C. Icahn Institute for Gene Therapy and Molecular Medicine, Mt. Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA. gwendalyn.randolph@mssm.edu

ABSTRACT
Much remains to be learned about the physiologic events that promote monocytes to become lymph-homing dendritic cells (DCs). In a model of transendothelial trafficking, some monocytes become DCs in response to endogenous signals. These DCs migrate across endothelium in the ablumenal-to-lumenal direction (reverse transmigration), reminiscent of the migration into lymphatic vessels. Here we show that the subpopulation of monocytes that expresses CD16 (Fcgamma receptor III) is predisposed to become migratory DCs. The vast majority of cells derived from CD16(+) monocytes reverse transmigrated, and their presence was associated with migratory cells expressing high levels of CD86 and human histocompatibility leukocyte antigen (HLA)-DR, and robust capacity to induce allogeneic T cell proliferation. A minority of CD16(-) monocytes reverse transmigrated, and these cells stimulated T cell proliferation less efficiently. CD16 was not functionally required for reverse transmigration, but promoted cell survival when yeast particles (zymosan) were present as a maturation stimulus in the subendothelial matrix. The cell surface phenotype and migratory characteristics of CD16(+) monocytes were inducible in CD16(-) monocytes by preincubation with TGFbeta1. We propose that CD16(+) monocytes may contribute significantly to precursors for DCs that transiently survey tissues and migrate to lymph nodes via afferent lymphatic vessels.

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