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Macrophage-dependent apoptosis of CD4+ T lymphocytes from HIV-infected individuals is mediated by FasL and tumor necrosis factor.

Badley AD, Dockrell D, Simpson M, Schut R, Lynch DH, Leibson P, Paya CV - J. Exp. Med. (1997)

Bottom Line: This study addresses whether antigen-presenting cells such as human macrophages mediate apoptosis of CD4+ T cells from HIV-infected individuals.Uninfected human macrophages, and to a larger degree, HIV-infected macrophages mediate apoptosis of T cells from HIV-infected, but not from uninfected control individuals.These results support a role for macrophage-associated FasL and TNF in the selective depletion of CD4+ T cells in HIV-infected individuals.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Mayo Clinic, Rochester, Minnesota 55901, USA.

ABSTRACT
Apoptosis of bystander uninfected CD4+ T lymphocytes by neighboring HIV-infected cells is observed in cell culture and in lymphoid tissue of HIV-infected individuals. This study addresses whether antigen-presenting cells such as human macrophages mediate apoptosis of CD4+ T cells from HIV-infected individuals. Uninfected human macrophages, and to a larger degree, HIV-infected macrophages mediate apoptosis of T cells from HIV-infected, but not from uninfected control individuals. This macrophage-dependent killing targets CD4+, but not CD8+ T lymphocytes from HIV-infected individuals, and direct contact between macrophages and lymphocytes is required. Additional analyses indicated that the apoptosis-inducing ligands, FasL and tumor necrosis factor (TNF), mediate this macrophage-induced apoptosis of CD4+ T cells. These results support a role for macrophage-associated FasL and TNF in the selective depletion of CD4+ T cells in HIV-infected individuals.

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(A) MDM induced apoptosis of CD4+ T lymphocytes is partially mediated by FasL. PBL from HIV-infected individuals were incubated alone or with HIV-infected macrophages at an effector/target ratio  of 5:1, either in the absence or presence of blocking (Fab′ M3) or nonblocking (Fab′ M33) anti-Fas antibodies (10 μg/well). In all cases, Fab′  M33 did not significantly alter the level of apoptosis seen in the PBL coincubated with macrophages without antibody. In order to determine the  contribution of FasL to MDM killing of PBLs, percent specific inhibition  was calculated as follows: ([apoptosis of PBL coincubated with MDM −  apoptosis of PBL coincubated with Fab′3 and MDM] [apoptosis of PBL  coincubated with MDM − apoptosis of PBL incubated alone]). The  mean spontaneous apoptosis was 20.7 ± 13.7%. (B) Syngeneic apoptosis  of susceptible CD4+ T cells by HIV-infected MDM. (Left) Lymphocyte  blasts from an HIV seronegative individual (HIV(−) BLASTS) were incubated with 3 × 106 syngeneic HIV-infected MDM (HIV-MDM) either  alone (∅) or in the presence of blocking (Fab′ M3) or nonblocking (Fab′  M33) antibodies (10 μg/well). Spontaneous apoptosis was calculated by  incubating PBL blasts without macrophages (∅). Incubation with crosslinked agonistic M3 anti-Fas antibody lead to 27% CD4+ T cell apoptosis.  Freshly isolated PBLs had a spontaneous level of CD4+ T cell apoptosis of  2% which was not modified (3%) upon coincubation with HIV-infected  MDM. (Right) Freshly isolated PBLs from an HIV-infected individual  (HIV(+) PBL) were incubated with syngeneic HIV-infected MDMs (3 ×  106) in the absence or presence of Fab M3 or M33 (10 μg/ml) antibodies.  Cross-linked M3 antibodies induced 15% of CD4+ T cell apoptosis.
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Figure 4: (A) MDM induced apoptosis of CD4+ T lymphocytes is partially mediated by FasL. PBL from HIV-infected individuals were incubated alone or with HIV-infected macrophages at an effector/target ratio of 5:1, either in the absence or presence of blocking (Fab′ M3) or nonblocking (Fab′ M33) anti-Fas antibodies (10 μg/well). In all cases, Fab′ M33 did not significantly alter the level of apoptosis seen in the PBL coincubated with macrophages without antibody. In order to determine the contribution of FasL to MDM killing of PBLs, percent specific inhibition was calculated as follows: ([apoptosis of PBL coincubated with MDM − apoptosis of PBL coincubated with Fab′3 and MDM] [apoptosis of PBL coincubated with MDM − apoptosis of PBL incubated alone]). The mean spontaneous apoptosis was 20.7 ± 13.7%. (B) Syngeneic apoptosis of susceptible CD4+ T cells by HIV-infected MDM. (Left) Lymphocyte blasts from an HIV seronegative individual (HIV(−) BLASTS) were incubated with 3 × 106 syngeneic HIV-infected MDM (HIV-MDM) either alone (∅) or in the presence of blocking (Fab′ M3) or nonblocking (Fab′ M33) antibodies (10 μg/well). Spontaneous apoptosis was calculated by incubating PBL blasts without macrophages (∅). Incubation with crosslinked agonistic M3 anti-Fas antibody lead to 27% CD4+ T cell apoptosis. Freshly isolated PBLs had a spontaneous level of CD4+ T cell apoptosis of 2% which was not modified (3%) upon coincubation with HIV-infected MDM. (Right) Freshly isolated PBLs from an HIV-infected individual (HIV(+) PBL) were incubated with syngeneic HIV-infected MDMs (3 × 106) in the absence or presence of Fab M3 or M33 (10 μg/ml) antibodies. Cross-linked M3 antibodies induced 15% of CD4+ T cell apoptosis.

Mentions: We have previously described that FasL is partly responsible for the HIV-MDM–mediated apoptosis of Fas susceptible targets such as Jurkat T cells and PHA-IL2– treated T cell blasts (40). Based on the above results, we questioned whether HIV-MDM triggered apoptosis of CD4+ T cells from HIV seropositive individuals is mediated through FasL/Fas interactions. PBL from a series of 18 HIV-infected individuals were incubated with HIV-infected MDM (HIVMDM). The role of FasL was analyzed by adding blocking (M3 Fab′′) or nonblocking (M33 Fab′′) anti-Fas antibodies to wells in which MDM-HIV and PBL were coincubated. In a subgroup of patients (patients No. 1–8), Fas blocking antibodies (M3) completely reversed the CD4+ T cell apoptosis triggered by MDM-HIV (Fig. 4 A). However, in additional patients, M3 incompletely reversed CD4+ T cell apoptosis (patients No. 9–14) or had no effect (patients No. 15–18). In those patient samples in which M3 blocked HIV-MDM triggered apoptosis, the nonblocking M33 had no effect. From these results, it is inferred that apoptosis of CD4+ T cells from HIV-infected individuals triggered by HIV-infected MDM is partially mediated by FasL.


Macrophage-dependent apoptosis of CD4+ T lymphocytes from HIV-infected individuals is mediated by FasL and tumor necrosis factor.

Badley AD, Dockrell D, Simpson M, Schut R, Lynch DH, Leibson P, Paya CV - J. Exp. Med. (1997)

(A) MDM induced apoptosis of CD4+ T lymphocytes is partially mediated by FasL. PBL from HIV-infected individuals were incubated alone or with HIV-infected macrophages at an effector/target ratio  of 5:1, either in the absence or presence of blocking (Fab′ M3) or nonblocking (Fab′ M33) anti-Fas antibodies (10 μg/well). In all cases, Fab′  M33 did not significantly alter the level of apoptosis seen in the PBL coincubated with macrophages without antibody. In order to determine the  contribution of FasL to MDM killing of PBLs, percent specific inhibition  was calculated as follows: ([apoptosis of PBL coincubated with MDM −  apoptosis of PBL coincubated with Fab′3 and MDM] [apoptosis of PBL  coincubated with MDM − apoptosis of PBL incubated alone]). The  mean spontaneous apoptosis was 20.7 ± 13.7%. (B) Syngeneic apoptosis  of susceptible CD4+ T cells by HIV-infected MDM. (Left) Lymphocyte  blasts from an HIV seronegative individual (HIV(−) BLASTS) were incubated with 3 × 106 syngeneic HIV-infected MDM (HIV-MDM) either  alone (∅) or in the presence of blocking (Fab′ M3) or nonblocking (Fab′  M33) antibodies (10 μg/well). Spontaneous apoptosis was calculated by  incubating PBL blasts without macrophages (∅). Incubation with crosslinked agonistic M3 anti-Fas antibody lead to 27% CD4+ T cell apoptosis.  Freshly isolated PBLs had a spontaneous level of CD4+ T cell apoptosis of  2% which was not modified (3%) upon coincubation with HIV-infected  MDM. (Right) Freshly isolated PBLs from an HIV-infected individual  (HIV(+) PBL) were incubated with syngeneic HIV-infected MDMs (3 ×  106) in the absence or presence of Fab M3 or M33 (10 μg/ml) antibodies.  Cross-linked M3 antibodies induced 15% of CD4+ T cell apoptosis.
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Figure 4: (A) MDM induced apoptosis of CD4+ T lymphocytes is partially mediated by FasL. PBL from HIV-infected individuals were incubated alone or with HIV-infected macrophages at an effector/target ratio of 5:1, either in the absence or presence of blocking (Fab′ M3) or nonblocking (Fab′ M33) anti-Fas antibodies (10 μg/well). In all cases, Fab′ M33 did not significantly alter the level of apoptosis seen in the PBL coincubated with macrophages without antibody. In order to determine the contribution of FasL to MDM killing of PBLs, percent specific inhibition was calculated as follows: ([apoptosis of PBL coincubated with MDM − apoptosis of PBL coincubated with Fab′3 and MDM] [apoptosis of PBL coincubated with MDM − apoptosis of PBL incubated alone]). The mean spontaneous apoptosis was 20.7 ± 13.7%. (B) Syngeneic apoptosis of susceptible CD4+ T cells by HIV-infected MDM. (Left) Lymphocyte blasts from an HIV seronegative individual (HIV(−) BLASTS) were incubated with 3 × 106 syngeneic HIV-infected MDM (HIV-MDM) either alone (∅) or in the presence of blocking (Fab′ M3) or nonblocking (Fab′ M33) antibodies (10 μg/well). Spontaneous apoptosis was calculated by incubating PBL blasts without macrophages (∅). Incubation with crosslinked agonistic M3 anti-Fas antibody lead to 27% CD4+ T cell apoptosis. Freshly isolated PBLs had a spontaneous level of CD4+ T cell apoptosis of 2% which was not modified (3%) upon coincubation with HIV-infected MDM. (Right) Freshly isolated PBLs from an HIV-infected individual (HIV(+) PBL) were incubated with syngeneic HIV-infected MDMs (3 × 106) in the absence or presence of Fab M3 or M33 (10 μg/ml) antibodies. Cross-linked M3 antibodies induced 15% of CD4+ T cell apoptosis.
Mentions: We have previously described that FasL is partly responsible for the HIV-MDM–mediated apoptosis of Fas susceptible targets such as Jurkat T cells and PHA-IL2– treated T cell blasts (40). Based on the above results, we questioned whether HIV-MDM triggered apoptosis of CD4+ T cells from HIV seropositive individuals is mediated through FasL/Fas interactions. PBL from a series of 18 HIV-infected individuals were incubated with HIV-infected MDM (HIVMDM). The role of FasL was analyzed by adding blocking (M3 Fab′′) or nonblocking (M33 Fab′′) anti-Fas antibodies to wells in which MDM-HIV and PBL were coincubated. In a subgroup of patients (patients No. 1–8), Fas blocking antibodies (M3) completely reversed the CD4+ T cell apoptosis triggered by MDM-HIV (Fig. 4 A). However, in additional patients, M3 incompletely reversed CD4+ T cell apoptosis (patients No. 9–14) or had no effect (patients No. 15–18). In those patient samples in which M3 blocked HIV-MDM triggered apoptosis, the nonblocking M33 had no effect. From these results, it is inferred that apoptosis of CD4+ T cells from HIV-infected individuals triggered by HIV-infected MDM is partially mediated by FasL.

Bottom Line: This study addresses whether antigen-presenting cells such as human macrophages mediate apoptosis of CD4+ T cells from HIV-infected individuals.Uninfected human macrophages, and to a larger degree, HIV-infected macrophages mediate apoptosis of T cells from HIV-infected, but not from uninfected control individuals.These results support a role for macrophage-associated FasL and TNF in the selective depletion of CD4+ T cells in HIV-infected individuals.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Mayo Clinic, Rochester, Minnesota 55901, USA.

ABSTRACT
Apoptosis of bystander uninfected CD4+ T lymphocytes by neighboring HIV-infected cells is observed in cell culture and in lymphoid tissue of HIV-infected individuals. This study addresses whether antigen-presenting cells such as human macrophages mediate apoptosis of CD4+ T cells from HIV-infected individuals. Uninfected human macrophages, and to a larger degree, HIV-infected macrophages mediate apoptosis of T cells from HIV-infected, but not from uninfected control individuals. This macrophage-dependent killing targets CD4+, but not CD8+ T lymphocytes from HIV-infected individuals, and direct contact between macrophages and lymphocytes is required. Additional analyses indicated that the apoptosis-inducing ligands, FasL and tumor necrosis factor (TNF), mediate this macrophage-induced apoptosis of CD4+ T cells. These results support a role for macrophage-associated FasL and TNF in the selective depletion of CD4+ T cells in HIV-infected individuals.

Show MeSH
Related in: MedlinePlus