Chronic obstructive pulmonary disease (
COPD) is a multicomponent condition that is characterized by partially reversible airflow obstruction. Serum
surfactant protein D (
SP-D) is synthesized by type II pneumocytes and Clara cells and participates in
surfactant homeostasis and pulmonary host defense. Serum levels of
SP-D are raised in individuals with
COPD but there is no correlation between the serum level of
SP-D and the severity of airflow obstruction. Serum
SP-D is present in different forms that may have more utility as a
biomarker for
COPD. We report here the development of new
monoclonal antibodies to full length and cleaved
SP-D. We have assessed these and existing
antibodies in 98 individuals with
COPD recruited to the Evaluation of
COPD Longitudinally to Identify Predictive
Surrogate Endpoints (ECLIPSE) cohort. Our data show that neither
monoclonal antibodies to full length nor cleaved
SP-D provide additional information over that obtained with a polyclonal antibody. Moreover, levels of serum nitrosylated-
SP-D did not correlate with serum level of
SP-D or any clinical phenotype of
COPD. The measurement of modified
SP-D is of limited value in characterising individuals with
COPD.