Mycobacterium bovis BCG-infected mice are more susceptible to staphylococcal enterotoxin B-mediated toxic shock than uninfected mice despite reduced in vitro splenocyte responses to superantigens
| Autor: | Henk van Faassen, Yvan Chapdelaine, Subash Sad, Renu Dudani, Dean K. Smith, Joao A. Pedras-Vasconcelos |
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| Rok vydání: | 2002 |
| Předmět: |
CD4-Positive T-Lymphocytes
Cellular immunity Staphylococcus aureus Immunology Antigen-Presenting Cells Enterotoxin Biology CD8-Positive T-Lymphocytes Microbiology Enterotoxins Interferon-gamma Mice Immune system Antigen medicine Superantigen Splenocyte Animals Tuberculosis Interferon gamma Antigen-presenting cell Cells Cultured Mice Inbred BALB C Superantigens Bacterial Infections Mycobacterium bovis Shock Septic Infectious Diseases Hyaluronan Receptors Parasitology Female Disease Susceptibility Spleen medicine.drug |
| Zdroj: | Infection and immunity. 70(8) |
| ISSN: | 0019-9567 |
| Popis: | Type 1 T-cell responses against intracellular pathogens play a crucial role in mediating protection. We examined whether the induction of a strong type 1 T-cell response during a chronic bacterial infection influences responses to superantigens capable of inducing acute shock. Intravenous infection of mice withMycobacterium bovisBCG appeared to induce a progressive anergy towards staphylococcal enterotoxin B (SEB) and towards antigen preparation of BCG (BCG-Ag) itself, based on diminished gamma interferon (IFN-γ) production by SEB- and BCG-Ag-stimulated splenocytes from infected mice. In contrast to these in vitro results, injection of SEB into BCG-infected mice led to a dramatic increase in the serum IFN-γ levels and the death of infected but not of control mice. In vitro hyporesponsiveness towards SEB and BCG-Ag occurred only with unfractionated splenocyte cultures, as purified T cells from infected mice produced higher levels of IFN-γ. Hyporesponsiveness towards SEB and BCG-Ag in unfractionated splenocyte cultures was not due to suppressive antigen-presenting cells (APCs), as APCs from infected mice stimulated higher levels of IFN-γ from purified T cells. The diminished IFN-γ levels observed with bulk splenocytes appear to be due to changes in the T-cell-to-APC ratio that result in a decreased proportion of T cells, coupled to reduced proliferative responses and an increased susceptibility of effector T cells to activation-induced cell death in vitro. Our results indicate that the reported phenomena of T-cell anergy during mycobacterial infection may be an in vitro consequence of the development of a strong type 1 response in vivo. |
| Databáze: | OpenAIRE |
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