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Protection from respiratory virus infections can be mediated by antigen-specific CD4(+) T cells that persist in the lungs.

Hogan RJ, Zhong W, Usherwood EJ, Cookenham T, Roberts AD, Woodland DL - J. Exp. Med. (2001)

Bottom Line: For example, although phenotypically distinct populations of memory CD4(+) T cells have been identified in different secondary lymphoid tissues, it is not known which subpopulations mediate protective cellular immunity.A large proportion of these cells possess a highly activated phenotype (CD44(hi), CD62L(lo), CD43(hi), and CD25(hi)) and express immediate effector function as indicated by the production of interferon gamma after a 5-h restimulation in vitro.Taken together, these data demonstrate that activated memory CD4(+) T cells persisting at mucosal sites play a critical role in mediating protective cellular immunity.

View Article: PubMed Central - PubMed

Affiliation: Trudeau Institute, Saranac Lake, New York 12983, USA.

ABSTRACT
Although CD4(+) T cells have been shown to mediate protective cellular immunity against respiratory virus infections, the underlying mechanisms are poorly understood. For example, although phenotypically distinct populations of memory CD4(+) T cells have been identified in different secondary lymphoid tissues, it is not known which subpopulations mediate protective cellular immunity. In this report, we demonstrate that virus-specific CD4(+) T cells persist in the lung tissues and airways for several months after Sendai virus infection of C57BL/6 mice. A large proportion of these cells possess a highly activated phenotype (CD44(hi), CD62L(lo), CD43(hi), and CD25(hi)) and express immediate effector function as indicated by the production of interferon gamma after a 5-h restimulation in vitro. Furthermore, intratracheal adoptive transfer of lung memory cells into beta2m-deficient mice demonstrated that lung-resident virus-specific CD4(+) T cells mediated a substantial degree of protection against secondary virus infection. Taken together, these data demonstrate that activated memory CD4(+) T cells persisting at mucosal sites play a critical role in mediating protective cellular immunity.

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BAL memory cells confer protection against Sendai virus infection. (A) 10 naive C57BL/6 mice were intranasally infected with 500 EID50 Sendai virus. 4 h before infection, the mice received either memory BAL cells (5 × 105 cells in 100 μl, n = 5), or control PBS (100 μl, n = 5) intratracheally. The BAL cells in this experiment were derived from C57BL/6 mice that had recovered from infection with 500 EID50 Sendai virus (35 d after infection). (B) 16 naive β2m-deficient mice were intranasally infected with 500 EID50 Sendai virus. 4 h before infection, each mouse received either Sendai memory BAL cells (106 cells in 100 μl, n = 6), influenza memory BAL cells (106 cells in 100 μl, n = 6), or control PBS (100 μl, n = 4) intratracheally. In this experiment, Sendai memory BAL cells were obtained from C57BL/6 mice at day 40 after infection, whereas influenza memory BAL cells were obtained from C57BL/6 mice at day 41 after infection. In both A and B, virus titers in the lung were determined 4 d after transfer by titrating lung homogenates in embryonated chicken eggs, followed by hemagglutination assays. Where indicated, the difference in viral titers among each group was determined to be statistically significant as based on a standard t test. The data are expressed as log10EID50 and are representative of three independent experiments.
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Figure 3: BAL memory cells confer protection against Sendai virus infection. (A) 10 naive C57BL/6 mice were intranasally infected with 500 EID50 Sendai virus. 4 h before infection, the mice received either memory BAL cells (5 × 105 cells in 100 μl, n = 5), or control PBS (100 μl, n = 5) intratracheally. The BAL cells in this experiment were derived from C57BL/6 mice that had recovered from infection with 500 EID50 Sendai virus (35 d after infection). (B) 16 naive β2m-deficient mice were intranasally infected with 500 EID50 Sendai virus. 4 h before infection, each mouse received either Sendai memory BAL cells (106 cells in 100 μl, n = 6), influenza memory BAL cells (106 cells in 100 μl, n = 6), or control PBS (100 μl, n = 4) intratracheally. In this experiment, Sendai memory BAL cells were obtained from C57BL/6 mice at day 40 after infection, whereas influenza memory BAL cells were obtained from C57BL/6 mice at day 41 after infection. In both A and B, virus titers in the lung were determined 4 d after transfer by titrating lung homogenates in embryonated chicken eggs, followed by hemagglutination assays. Where indicated, the difference in viral titers among each group was determined to be statistically significant as based on a standard t test. The data are expressed as log10EID50 and are representative of three independent experiments.

Mentions: Given the ability of antigen-specific T cells in the lungs to rapidly produce IFN-γ directly ex vivo, we next asked whether these cells would mediate protection against subsequent Sendai virus infection. Thus, total BAL cells were isolated from the lungs of mice that had recovered from a Sendai virus infection (day 35 after infection) and intratracheally transferred directly into the lungs of naive C57BL/6 mice. This procedure instills cells directly into the lung airways and it has been shown that these cells are able persist in the airways for several weeks after transfer (unpublished observations). 4 h after transfer, the mice were infected with Sendai virus and viral titers in the lung were then assessed 4 d later. As shown in Fig. 3 A, mice that received the memory BAL cells had a significantly reduced viral load in the lung compared with PBS control mice (an average reduction of 250-fold, P = 0.014). Although the intratracheal transfer of memory BAL cells had a significant impact on lung virus titers, it was not clear exactly which cells in the BAL mediated this effect, or whether CD4+ T cells were involved. Thus, to specifically investigate the role of virus-specific CD4+ T cells in the lung airways, we intratracheally transferred Sendai memory BAL cells (day 40 after infection) into naive β2m-deficient mice. These mice express undetectable levels of H-2Kb resulting in a significant impairment of the CD8+ T cell response to the immunodominant NP324–332/Kb-epitope 1618. It should be noted that β2m-deficient mice do express low levels of functional H-2Db, but that this restricting element is not involved in the effector CD8+ T cell response to Sendai virus in H-2b mice 16. Two sets of control β2m-deficient mice received either PBS or BAL cells isolated from influenza memory mice (day 41 after infection). As shown in Fig. 3 B, the β2m-deficient mice that received Sendai memory BAL cells were significantly more efficient at controlling the virus load than the PBS control group (P < 0.009) or the influenza control group (P < 0.023). These data cannot be readily explained by the transfer of memory B or antibody-producing plasma cells, as these cells typically represent <0.5% of the cells in the BAL. Similarly, the fact that the BAL cells were washed before transfer rules out the transfer of passive antibody. Thus, the data suggest that the presence of virus-specific CD4+ T cells in the lungs has a significant impact on viral load during the initial stages of infection.


Protection from respiratory virus infections can be mediated by antigen-specific CD4(+) T cells that persist in the lungs.

Hogan RJ, Zhong W, Usherwood EJ, Cookenham T, Roberts AD, Woodland DL - J. Exp. Med. (2001)

BAL memory cells confer protection against Sendai virus infection. (A) 10 naive C57BL/6 mice were intranasally infected with 500 EID50 Sendai virus. 4 h before infection, the mice received either memory BAL cells (5 × 105 cells in 100 μl, n = 5), or control PBS (100 μl, n = 5) intratracheally. The BAL cells in this experiment were derived from C57BL/6 mice that had recovered from infection with 500 EID50 Sendai virus (35 d after infection). (B) 16 naive β2m-deficient mice were intranasally infected with 500 EID50 Sendai virus. 4 h before infection, each mouse received either Sendai memory BAL cells (106 cells in 100 μl, n = 6), influenza memory BAL cells (106 cells in 100 μl, n = 6), or control PBS (100 μl, n = 4) intratracheally. In this experiment, Sendai memory BAL cells were obtained from C57BL/6 mice at day 40 after infection, whereas influenza memory BAL cells were obtained from C57BL/6 mice at day 41 after infection. In both A and B, virus titers in the lung were determined 4 d after transfer by titrating lung homogenates in embryonated chicken eggs, followed by hemagglutination assays. Where indicated, the difference in viral titers among each group was determined to be statistically significant as based on a standard t test. The data are expressed as log10EID50 and are representative of three independent experiments.
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Related In: Results  -  Collection

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Figure 3: BAL memory cells confer protection against Sendai virus infection. (A) 10 naive C57BL/6 mice were intranasally infected with 500 EID50 Sendai virus. 4 h before infection, the mice received either memory BAL cells (5 × 105 cells in 100 μl, n = 5), or control PBS (100 μl, n = 5) intratracheally. The BAL cells in this experiment were derived from C57BL/6 mice that had recovered from infection with 500 EID50 Sendai virus (35 d after infection). (B) 16 naive β2m-deficient mice were intranasally infected with 500 EID50 Sendai virus. 4 h before infection, each mouse received either Sendai memory BAL cells (106 cells in 100 μl, n = 6), influenza memory BAL cells (106 cells in 100 μl, n = 6), or control PBS (100 μl, n = 4) intratracheally. In this experiment, Sendai memory BAL cells were obtained from C57BL/6 mice at day 40 after infection, whereas influenza memory BAL cells were obtained from C57BL/6 mice at day 41 after infection. In both A and B, virus titers in the lung were determined 4 d after transfer by titrating lung homogenates in embryonated chicken eggs, followed by hemagglutination assays. Where indicated, the difference in viral titers among each group was determined to be statistically significant as based on a standard t test. The data are expressed as log10EID50 and are representative of three independent experiments.
Mentions: Given the ability of antigen-specific T cells in the lungs to rapidly produce IFN-γ directly ex vivo, we next asked whether these cells would mediate protection against subsequent Sendai virus infection. Thus, total BAL cells were isolated from the lungs of mice that had recovered from a Sendai virus infection (day 35 after infection) and intratracheally transferred directly into the lungs of naive C57BL/6 mice. This procedure instills cells directly into the lung airways and it has been shown that these cells are able persist in the airways for several weeks after transfer (unpublished observations). 4 h after transfer, the mice were infected with Sendai virus and viral titers in the lung were then assessed 4 d later. As shown in Fig. 3 A, mice that received the memory BAL cells had a significantly reduced viral load in the lung compared with PBS control mice (an average reduction of 250-fold, P = 0.014). Although the intratracheal transfer of memory BAL cells had a significant impact on lung virus titers, it was not clear exactly which cells in the BAL mediated this effect, or whether CD4+ T cells were involved. Thus, to specifically investigate the role of virus-specific CD4+ T cells in the lung airways, we intratracheally transferred Sendai memory BAL cells (day 40 after infection) into naive β2m-deficient mice. These mice express undetectable levels of H-2Kb resulting in a significant impairment of the CD8+ T cell response to the immunodominant NP324–332/Kb-epitope 1618. It should be noted that β2m-deficient mice do express low levels of functional H-2Db, but that this restricting element is not involved in the effector CD8+ T cell response to Sendai virus in H-2b mice 16. Two sets of control β2m-deficient mice received either PBS or BAL cells isolated from influenza memory mice (day 41 after infection). As shown in Fig. 3 B, the β2m-deficient mice that received Sendai memory BAL cells were significantly more efficient at controlling the virus load than the PBS control group (P < 0.009) or the influenza control group (P < 0.023). These data cannot be readily explained by the transfer of memory B or antibody-producing plasma cells, as these cells typically represent <0.5% of the cells in the BAL. Similarly, the fact that the BAL cells were washed before transfer rules out the transfer of passive antibody. Thus, the data suggest that the presence of virus-specific CD4+ T cells in the lungs has a significant impact on viral load during the initial stages of infection.

Bottom Line: For example, although phenotypically distinct populations of memory CD4(+) T cells have been identified in different secondary lymphoid tissues, it is not known which subpopulations mediate protective cellular immunity.A large proportion of these cells possess a highly activated phenotype (CD44(hi), CD62L(lo), CD43(hi), and CD25(hi)) and express immediate effector function as indicated by the production of interferon gamma after a 5-h restimulation in vitro.Taken together, these data demonstrate that activated memory CD4(+) T cells persisting at mucosal sites play a critical role in mediating protective cellular immunity.

View Article: PubMed Central - PubMed

Affiliation: Trudeau Institute, Saranac Lake, New York 12983, USA.

ABSTRACT
Although CD4(+) T cells have been shown to mediate protective cellular immunity against respiratory virus infections, the underlying mechanisms are poorly understood. For example, although phenotypically distinct populations of memory CD4(+) T cells have been identified in different secondary lymphoid tissues, it is not known which subpopulations mediate protective cellular immunity. In this report, we demonstrate that virus-specific CD4(+) T cells persist in the lung tissues and airways for several months after Sendai virus infection of C57BL/6 mice. A large proportion of these cells possess a highly activated phenotype (CD44(hi), CD62L(lo), CD43(hi), and CD25(hi)) and express immediate effector function as indicated by the production of interferon gamma after a 5-h restimulation in vitro. Furthermore, intratracheal adoptive transfer of lung memory cells into beta2m-deficient mice demonstrated that lung-resident virus-specific CD4(+) T cells mediated a substantial degree of protection against secondary virus infection. Taken together, these data demonstrate that activated memory CD4(+) T cells persisting at mucosal sites play a critical role in mediating protective cellular immunity.

Show MeSH
Related in: MedlinePlus