Our findings also suggest that MIP-1a could also be used for the differential diagnosis of lung cancer from tuberculosis (sensitivity 100 %/specificity 70 %), from parapneumonic effusions (sensitivity 80 %/specificity 100 %) and especially from metastatic tumors of non-lung origin (sensitivity 67 %/specificity 100 %), which are more difficult to distinguish. The gene discussed is CCL3; the disease is tuberculosis.