Arellano-Orden E, et al. - The target of this trial was to determine the interaction networks of a number of plasma acute phase reactants (APRs) in chronic obstructive pulmonary disease (COPD), with emphasis on their relationship with disease severity. A rise was noted in the circulating concentrations of haptoglobin and tissue plasminogen activator (tPA), in parallel with the severity of the disease. Increasing disease severity correlated with distinct intricate networks of APRs. These were evident in advanced stages. Various networks of APRs were detected in COPD, which were substantially linked to the disease severity.