CEACAM5 and chronic obstructive pulmonary disease: In contrast, surfactant protein-A (SP-A), surfactant protein-D (SP-D), lactate dehydrogenase (LDH), carcinoembryonic antigen (CEA) and cytokeratin fragment (CYFRA) ranges in patients with aPAP partially or completely overlapped those in healthy volunteers and in patients with COPD or asthma (Table 2).