METHODS: C57BL/6 mice were given reverse osmosis drinking water with or without the non-absorbable antibiotic, streptomycin (0.5 g/250 ml). After 2 weeks mice were intranasally inoculated with 30 μl of 2 x105 plaque forming units of SeV. On day 8 post infection lung cells were harvested. ILC’s were identified by flow cytometry as being Lin- CD4+ lymphocytes, with intracellular staining used to determine IFNγ levels.
RESULTS: ILCs represented 5.1+/-0.6% (mean+/-SEM) of the lymphoid cells in the murine lung during SeV infection, and this was not altered by streptomycin treatment (4.3+/-0.4%, p=0.3, n=5). Similarly, the absolute numbers of ILCs was not affected by antibiotic treatment (p=0.2). However, the frequency of IFNγ producing ILCs increased from 0.90+/-0.4% to 2.85+/-0.6% with streptomycin treatment (p=0.04, n=4).
CONCLUSIONS: ILCs, while being a small population, may represent the cell type that is responsible for increased pulmonary IFNγ during a respiratory viral infection after disruption of gastrointestinal microbiota.