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Antigen-driven C-C chemokine-mediated HIV-1 suppression by CD4(+) T cells from exposed uninfected individuals expressing the wild-type CCR-5 allele.

Furci L, Scarlatti G, Burastero S, Tambussi G, Colognesi C, Quillent C, Longhi R, Loverro P, Borgonovo B, Gaffi D, Carrow E, Malnati M, Lusso P, Siccardi AG, Lazzarin A, Beretta A - J. Exp. Med. (1997)

Bottom Line: The latter has been associated with a 32-base pair deletion in the C-C chemokine receptor gene CCR-5, the major coreceptor of macrophage-tropic strains of HIV-1.These cells produce very high levels of C-C chemokines when stimulated by the specific antigen and suppress selectively the replication of macrophage-tropic, but not T cell-tropic, strains of HIV-1.These chemokine-producing helper cells may be part of a protective immune response that could be potentially exploited for vaccine development.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Technological Research, San Raffaele Scientific Institute, Milan, Italy.

ABSTRACT
Despite repeated exposure to HIV-1, certain individuals remain persistently uninfected. Such exposed uninfected (EU) people show evidence of HIV-1-specific T cell immunity and, in rare cases, selective resistance to infection by macrophage-tropic strains of HIV-1. The latter has been associated with a 32-base pair deletion in the C-C chemokine receptor gene CCR-5, the major coreceptor of macrophage-tropic strains of HIV-1. We have undertaken an analysis of the HIV-specific T cell responses in 12 EU individuals who were either homozygous for the wild-type CCR-5 allele or heterozygous for the deletion allele (CCR-5Delta32). We have found evidence of an oligoclonal T cell response mediated by helper T cells specific for a conserved region of the HIV-1 envelope. These cells produce very high levels of C-C chemokines when stimulated by the specific antigen and suppress selectively the replication of macrophage-tropic, but not T cell-tropic, strains of HIV-1. These chemokine-producing helper cells may be part of a protective immune response that could be potentially exploited for vaccine development.

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(a) Reactivity of EU T cells to different HIV-1 gp120 peptides. PBMC from exposed uninfected (EU) partners (closed symbols) and  control unexposed uninfected (UU) individuals (open symbols) were cultured in RPMI medium supplemented with 5% human serum in the  presence of 30 μg/ml of peptide. On day 7, cells were washed and then  incubated for a further 5 d in fresh medium containing rIL-2 (20 U/ml).  On day 12, 3 × 104 T cells were cultivated together with 105 autologous  irradiated PBMC in the presence of the specific peptide and the proliferative responses measured after 3 d by [3H]thymidine incorporation. The  data are expressed as stimulation index (S.I.). An individual was considered positive when the S.I. was >2. The peptides used were derived from  the following HIV-1IIIb sequence: peptide C1, HEDIISLWDQSLKPCVKLT; peptide V3, RIHIGPGRAFYTTKN; peptide C4, KQFINMWQEWGKAMYA; peptide C5, SELYKYKVVKIEPLGVAPTKAKRR.  The sequence of the control peptide was TPSLLEQEVKPSTELEYLGPDEND. (b) Frequency of gp120–C5 specific T cells in EU partners. (Left)  A representative experiment with PBMC from one EU and one control  UU individual. (Right) Individual frequencies of C5-specific T cells from  EU and UU PBMC.
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Figure 1: (a) Reactivity of EU T cells to different HIV-1 gp120 peptides. PBMC from exposed uninfected (EU) partners (closed symbols) and control unexposed uninfected (UU) individuals (open symbols) were cultured in RPMI medium supplemented with 5% human serum in the presence of 30 μg/ml of peptide. On day 7, cells were washed and then incubated for a further 5 d in fresh medium containing rIL-2 (20 U/ml). On day 12, 3 × 104 T cells were cultivated together with 105 autologous irradiated PBMC in the presence of the specific peptide and the proliferative responses measured after 3 d by [3H]thymidine incorporation. The data are expressed as stimulation index (S.I.). An individual was considered positive when the S.I. was >2. The peptides used were derived from the following HIV-1IIIb sequence: peptide C1, HEDIISLWDQSLKPCVKLT; peptide V3, RIHIGPGRAFYTTKN; peptide C4, KQFINMWQEWGKAMYA; peptide C5, SELYKYKVVKIEPLGVAPTKAKRR. The sequence of the control peptide was TPSLLEQEVKPSTELEYLGPDEND. (b) Frequency of gp120–C5 specific T cells in EU partners. (Left) A representative experiment with PBMC from one EU and one control UU individual. (Right) Individual frequencies of C5-specific T cells from EU and UU PBMC.

Mentions: HIV-specific T cell responses in the EU partners were detected using three HIV gp120 envelope peptides containing known T cell epitopes (20) plus an additional peptide corresponding to the fifth conserved region of gp120 (peptide C5). Proliferative responses to the peptides were measured after a single round of stimulation of fresh PBMC. Eighteen unexposed uninfected (UU) subjects were used as controls. The C5 peptide stimulated 9 of 11 EU PBMC tested but none of the UU PBMC, whereas the other three peptides had no activity except for the V3 peptide, which stimulated one EU PBMC and one UU PBMC (Fig. 1 a). These results indicated that the T cell repertoire of EU but not UU individuals contains a high number of gp120-C5–specific T cells. To quantify more precisely the differences between EU and UU individuals we performed limiting dilution analysis of EU and UU peripheral T lymphocytes upon stimulation with the C5 peptide. As shown in Fig. 1 b, the mean frequency of C5-specific EU T cells was significantly higher (P <0.001) than that of UU T cells (1 in 7,700 ± 4,700 for EU versus 1 in 18,000 ± 6,500 for UU). The C5 peptide was therefore selected for further analysis.


Antigen-driven C-C chemokine-mediated HIV-1 suppression by CD4(+) T cells from exposed uninfected individuals expressing the wild-type CCR-5 allele.

Furci L, Scarlatti G, Burastero S, Tambussi G, Colognesi C, Quillent C, Longhi R, Loverro P, Borgonovo B, Gaffi D, Carrow E, Malnati M, Lusso P, Siccardi AG, Lazzarin A, Beretta A - J. Exp. Med. (1997)

(a) Reactivity of EU T cells to different HIV-1 gp120 peptides. PBMC from exposed uninfected (EU) partners (closed symbols) and  control unexposed uninfected (UU) individuals (open symbols) were cultured in RPMI medium supplemented with 5% human serum in the  presence of 30 μg/ml of peptide. On day 7, cells were washed and then  incubated for a further 5 d in fresh medium containing rIL-2 (20 U/ml).  On day 12, 3 × 104 T cells were cultivated together with 105 autologous  irradiated PBMC in the presence of the specific peptide and the proliferative responses measured after 3 d by [3H]thymidine incorporation. The  data are expressed as stimulation index (S.I.). An individual was considered positive when the S.I. was >2. The peptides used were derived from  the following HIV-1IIIb sequence: peptide C1, HEDIISLWDQSLKPCVKLT; peptide V3, RIHIGPGRAFYTTKN; peptide C4, KQFINMWQEWGKAMYA; peptide C5, SELYKYKVVKIEPLGVAPTKAKRR.  The sequence of the control peptide was TPSLLEQEVKPSTELEYLGPDEND. (b) Frequency of gp120–C5 specific T cells in EU partners. (Left)  A representative experiment with PBMC from one EU and one control  UU individual. (Right) Individual frequencies of C5-specific T cells from  EU and UU PBMC.
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Related In: Results  -  Collection

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Figure 1: (a) Reactivity of EU T cells to different HIV-1 gp120 peptides. PBMC from exposed uninfected (EU) partners (closed symbols) and control unexposed uninfected (UU) individuals (open symbols) were cultured in RPMI medium supplemented with 5% human serum in the presence of 30 μg/ml of peptide. On day 7, cells were washed and then incubated for a further 5 d in fresh medium containing rIL-2 (20 U/ml). On day 12, 3 × 104 T cells were cultivated together with 105 autologous irradiated PBMC in the presence of the specific peptide and the proliferative responses measured after 3 d by [3H]thymidine incorporation. The data are expressed as stimulation index (S.I.). An individual was considered positive when the S.I. was >2. The peptides used were derived from the following HIV-1IIIb sequence: peptide C1, HEDIISLWDQSLKPCVKLT; peptide V3, RIHIGPGRAFYTTKN; peptide C4, KQFINMWQEWGKAMYA; peptide C5, SELYKYKVVKIEPLGVAPTKAKRR. The sequence of the control peptide was TPSLLEQEVKPSTELEYLGPDEND. (b) Frequency of gp120–C5 specific T cells in EU partners. (Left) A representative experiment with PBMC from one EU and one control UU individual. (Right) Individual frequencies of C5-specific T cells from EU and UU PBMC.
Mentions: HIV-specific T cell responses in the EU partners were detected using three HIV gp120 envelope peptides containing known T cell epitopes (20) plus an additional peptide corresponding to the fifth conserved region of gp120 (peptide C5). Proliferative responses to the peptides were measured after a single round of stimulation of fresh PBMC. Eighteen unexposed uninfected (UU) subjects were used as controls. The C5 peptide stimulated 9 of 11 EU PBMC tested but none of the UU PBMC, whereas the other three peptides had no activity except for the V3 peptide, which stimulated one EU PBMC and one UU PBMC (Fig. 1 a). These results indicated that the T cell repertoire of EU but not UU individuals contains a high number of gp120-C5–specific T cells. To quantify more precisely the differences between EU and UU individuals we performed limiting dilution analysis of EU and UU peripheral T lymphocytes upon stimulation with the C5 peptide. As shown in Fig. 1 b, the mean frequency of C5-specific EU T cells was significantly higher (P <0.001) than that of UU T cells (1 in 7,700 ± 4,700 for EU versus 1 in 18,000 ± 6,500 for UU). The C5 peptide was therefore selected for further analysis.

Bottom Line: The latter has been associated with a 32-base pair deletion in the C-C chemokine receptor gene CCR-5, the major coreceptor of macrophage-tropic strains of HIV-1.These cells produce very high levels of C-C chemokines when stimulated by the specific antigen and suppress selectively the replication of macrophage-tropic, but not T cell-tropic, strains of HIV-1.These chemokine-producing helper cells may be part of a protective immune response that could be potentially exploited for vaccine development.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Technological Research, San Raffaele Scientific Institute, Milan, Italy.

ABSTRACT
Despite repeated exposure to HIV-1, certain individuals remain persistently uninfected. Such exposed uninfected (EU) people show evidence of HIV-1-specific T cell immunity and, in rare cases, selective resistance to infection by macrophage-tropic strains of HIV-1. The latter has been associated with a 32-base pair deletion in the C-C chemokine receptor gene CCR-5, the major coreceptor of macrophage-tropic strains of HIV-1. We have undertaken an analysis of the HIV-specific T cell responses in 12 EU individuals who were either homozygous for the wild-type CCR-5 allele or heterozygous for the deletion allele (CCR-5Delta32). We have found evidence of an oligoclonal T cell response mediated by helper T cells specific for a conserved region of the HIV-1 envelope. These cells produce very high levels of C-C chemokines when stimulated by the specific antigen and suppress selectively the replication of macrophage-tropic, but not T cell-tropic, strains of HIV-1. These chemokine-producing helper cells may be part of a protective immune response that could be potentially exploited for vaccine development.

Show MeSH
Related in: MedlinePlus