In the present work we demonstrated that the respiratory challenge with S. pneumonie increased levels of G-CSF mRNA and reduced CXCL12 expression in the bone marrow of WNC mice which is in line with the results of Delano et al., [25], that showed, using a model of polymicrobial sepsis, that bone marrow CXCL12 mRNA abundance and specific CXCL12 levels were reduced during infections. The gene discussed is CXCL12; the disease is infection.