immunology of infectious and parasitic diseases - XXXVII Congress ...

SITE OF L. MAJOR INFECTION DETERMINES DOMINANT HOST CELL
PHENOTYPE
ERIC HENRIQUE ROMA 1,2 , FLÁVIA RIBEIRO-GOMES 1 , DAVID SACKS 1 ,
NATHAN PETERS 1 .
1 National Institutes of Allergy and Infectious Diseases, NIH – Bethesda, USA
2 Institute of Biological Sciences, Universidade Federal de Minas Gerais - Belo
Horizonte, Brazil
Introduction: The impact of the inoculation site on the outcome of infection with
the intracellular parasite Leishmania is poorly understood. We investigated the
acute interactions between L. major and phagocytic cells at different sites of
infection commonly used in studies of Leishmaniasis.
Methods and results: C57BL/6 mice were infected with L. major expressing
red fluorescent protein (RFP) by the subcutaneous (footpad) and intradermal
(ear) routes. At 2 and 48 hours post-infection, ears and footpads showed similar
numbers of CD11b + cells, where as ears had higher numbers on day 9. At all
time points tested, the number of infected cells was higher in the ear versus the
footpad. Phenotyping of RFP + cells revealed that the dominant infected
population in the ear were neutrophils at 2h, inflammatory monocytes at 48h,
and inflammatory and Ly6C low monocytes at 9 days post infection. In the
footpad, infected cells were predominantly macrophages/dendritic cells
(MΦ/DC) at 2h, Ly6C low monocytes at 48h, and MΦ/DC at 9 days. Infection in
the ear was associated with higher levels of IL-10 and CXCL1 mRNA versus the
footpad. Conclusion: The acute interaction between L. major and phagocytic
cells is different at different sites of infection. These observations may help to
explain divergent observations in studies of Leishmaniasis that employ different
inoculation sites.
Financial support: NIH and CAPES.