This regulation of Ly-6Chi monocytes by DCs may be explained by mutually nonexclusive scenarios of increased Flt3-L and GM-CSF, because altered phenotype of CD11b+Ly-6Chi monocytes is closely associated with elevated levels of Flt3-L and GM-CSF in the presence and absence, respectively, of CD11chi DCs following viral infection. The gene discussed is FLT3LG; the disease is viral infectious disease.