Regulation of CD8+ T Cells Undergoing Primary and Secondary Responses to Infection in the Same Host

105

101

During infection with lymphocytic choriomeningitis virus, CD8+ T cells differentiate rapidly into effectors (CD62LlowCD44high) that differentiate further into the central memory phenotype (CD62LhighCD44high) gradually. To evaluate whether this CD8+ T cell differentiation program operates in all infection models, we evaluated CD8+ T cell differentiation during infection of mice with recombinant intracellular bacteria, Listeria monocytogenes (LM) and Mycobacterium bovis (BCG), expressing OVA. We report that CD8+ T cells primed during infection with the attenuated pathogen BCG-OVA differentiated primarily into the central subset that correlated to reduced attrition of the primed cells subsequently. CD8+ T cells induced by LM-OVA also differentiated into central phenotype cells first, but the cells rapidly converted into effectors in contrast to BCG-OVA. Memory CD8+ T cells induced by both LM-OVA as well as BCG-OVA were functional in that they produced cytokines and proliferated extensively in response to antigenic stimulation after adoptive transfer. During LM-OVA infection, if CD8+ T cells were guided to compete for access to APCs, then they received reduced stimulation that was associated with increased differentiation into the central subset and reduced attrition subsequently. Similar effect was observed when CD8+ T cells encountered APCs selectively during the waning phase of LM-OVA infection. Taken together, our results indicate that the potency of the pathogen can influence the differentiation and fate of CD8+ T cells enormously, and the extent of attrition of primed CD8+ T cells correlates inversely to the early differentiation of CD8+ T cells primarily into the central CD8+ T cell subset.

Section: Discussionsupporting

confidence: 81%

Reducing the Stimulation of CD8+ T Cells during Infection with Intracellular Bacteria Promotes Differentiation Primarily into a Central (CD62LhighCD44high) Subset

Faassen

Saldanha

Gilbertson

et al. 2005

105

101

“…Using a dual adoptive transfer system, we directly compared the expansion of memory CD8 ϩ T cells created in the absence or presence of TCDD in the same host. Given that the magnitude of a memory response is thought to be influenced by the primary CD8 ϩ T cell response (38,40,44,45), it is logical to hypothesize that impairment of the primary response by an immunosuppressive compound will lead to an insufficient recall response. However, we show in this study that this is not necessarily the case.…”

Section: Discussionmentioning

confidence: 99%

Aryl Hydrocarbon Receptor Activation Impairs the Priming but Not the Recall of Influenza Virus-Specific CD8+ T Cells in the Lung

Lawrence

Roberts

Neumiller

et al. 2006

The response of CD8+ T cells to influenza virus is very sensitive to modulation by aryl hydrocarbon receptor (AhR) agonists; however, the mechanism underlying AhR-mediated alterations in CD8+ T cell function remains unclear. Moreover, very little is known regarding how AhR activation affects anamnestic CD8+ T cell responses. In this study, we analyzed how AhR activation by the pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alters the in vivo distribution and frequency of CD8+ T cells specific for three different influenza A virus epitopes during and after the resolution of a primary infection. We then determined the effects of TCDD on the expansion of virus-specific memory CD8+ T cells during recall challenge. Adoptive transfer of AhR-null CD8+ T cells into congenic AhR+/+ recipients, and the generation of CD45.2AhR−/−→CD45.1AhR+/+ chimeric mice demonstrate that AhR-regulated events within hemopoietic cells, but not directly within CD8+ T cells, underlie suppressed expansion of virus-specific CD8+ T cells during primary infection. Using a dual-adoptive transfer approach, we directly compared the responsiveness of virus-specific memory CD8+ T cells created in the presence or absence of TCDD, which revealed that despite profound suppression of the primary response to influenza virus, the recall response of virus-specific CD8+ T cells that form in the presence of TCDD is only mildly impaired. Thus, the delayed kinetics of the recall response in TCDD-treated mice reflects the fact that there are fewer memory cells at the time of reinfection rather than an inherent defect in the responsive capacity of virus-specific memory CD8+ cells.

“…We and others previously showed that contraction of the secondary CD8 ϩ T cell response is prolonged compared with contraction of the primary CD8 ϩ T cell response, independent of host environment or duration of infection (17,47,48). To investigate the kinetics of primary vs secondary CD4 ϩ T cell responses and compare the kinetics of CD4 ϩ and CD8 ϩ T cell responses, day 70 memory T cells from rLM-OVA-immune B6.PL mice (Thy1.1 ϩ ) were transferred into naive B6 recipients (Thy1.2 ϩ ), and on 1 day post-transfer, recipient mice were infected with rLM-OVA.…”

Section: Kinetics Of Primary Vs Secondary Cd4 ϩ T Cell Response In Thmentioning

confidence: 99%

Duration of Infection and Antigen Display Have Minimal Influence on the Kinetics of the CD4+ T Cell Response to Listeria monocytogenes Infection

Corbin

Harty

2004

Self Cite

The T cell response to infection consists of clonal expansion of effector cells, followed by contraction to memory levels. It was previously thought that the duration of infection determines the magnitude and kinetics of the T cell response. However, recent analysis revealed that transition between the expansion and contraction phases of the Ag-specific CD8+ T cell response is not affected by experimental manipulation in the duration of infection or Ag display. We studied whether the duration of infection and Ag display influenced the kinetics of the Ag-specific CD4+ T cell response to Listeria monocytogenes (LM) infection. We found that truncating infection and Ag display with antibiotic treatment as early as 24 h postinfection had minimal impact on the expansion or contraction of CD4+ T cells; however, the magnitudes of the Ag-specific CD4+ and CD8+ T cell responses were differentially affected by the timing of antibiotic treatment. Treatment of LM-infected mice with antibiotics at 24 h postinfection did not prevent generation of detectable CD4+ and CD8+ memory T cells at 28 days after infection, vigorous secondary expansion of these memory T cells, or protection against a subsequent LM challenge. These results demonstrate that events within the first few days of infection stimulate CD4+ and CD8+ T cell responses that are capable of carrying out the full program of expansion and contraction to functional memory, independently of prolonged infection or Ag display.