Chronic Leishmania donovani infection promotes bystander CD8+-T-cell expansion and heterologous immunity.
It has been proposed that long-lived memory T cells generated by vaccination or infection reside within a memory compartment that has a finite size. Consequently, in a variety of acute infection models interclonal competition has been shown to lead to attrition of preexisting memory CD8+ T cells. Contrary to expectations, therefore, we found that chronic Leishmania donovani infection of Listeria-immune mice results in heightened protection against subsequent Listeria challenge. This protection was associated with bystander expansion of Listeria-specific CD8+ T cells and a bias in these cells toward a central memory T-cell phenotype with an enhanced capacity for gamma interferon production. We propose that splenomegaly, which is characteristic of visceral leishmaniasis and other tropical infections, may help promote heterologous immunity by resetting the size of the memory compartment during chronic infection.
Polley
Rosalind
R
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom.
Sanos
Stephanie L
SL
Prickett
Sara
S
Haque
Ashraful
A
Kaye
Paul M
PM
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002908:Chronic Disease; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000378:metabolism; D007893:Leishmania donovani; D007898:Leishmaniasis, Visceral / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D013163:Splenomegaly / Q000276:immunology* / Q000469:parasitology
D007371:Interferon-gamma