Lipoproteins are major targets of the polyclonal human T cell response to Mycobacterium tuberculosis.
J Immunol
; 190(1): 278-84, 2013 Jan 01.
Article
em En
| MEDLINE
| ID: mdl-23197260
ABSTRACT
Most vaccines and basic studies of T cell epitopes in Mycobacterium tuberculosis emphasize water-soluble proteins that are secreted into the extracellular space and presented in the context of MHC class II. Much less is known about the role of Ags retained within the cell wall. We used polyclonal T cells from infected humans to probe for responses to immunodominant Ags in the M. tuberculosis cell wall. We found that the magnitude of response to secreted or cell wall intrinsic compounds was similar among healthy controls, patients with latent tuberculosis, and patients with active tuberculosis. Individual responses to secreted Ags and cell wall extract were strongly correlated (r(2) = 0.495, p = 0.001), suggesting that T cells responding to cell wall and secreted Ags are present at similar frequency. Surprisingly, T cell stimulatory factors intrinsic to the cell wall partition into organic solvents; however, these responses are not explained by CD1-mediated presentation of lipids. Instead, we find that molecules soluble in organic solvents are dependent upon MHC class II and recognized by IFN-γ-secreting CD4(+) T cells. We reasoned that MHC class II-dependent Ags extracting into lipid mixtures might be found among triacylated lipoproteins present in mycobacteria. We used M. tuberculosis lacking prolipoprotein signal peptidase A (lspA), an enzyme required for lipoprotein synthesis, to demonstrate loss of polyclonal T cell responses. Our results demonstrate the use of bacterial genetics to identify lipoproteins as an unexpected and immunodominant class of cell wall-associated Ags targeted by the polyclonal human T cell response to M. tuberculosis.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
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Ativação Linfocitária
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Subpopulações de Linfócitos T
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Lipoproteínas
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Mycobacterium tuberculosis
Tipo de estudo:
Prognostic_studies
Limite:
Adult
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Female
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Humans
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Male
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Middle aged
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article