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Surfactant proteins D and A in sputum
M Griese1, N Maderlechner, P Bufler
1Kinderpoliklinik, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Pettenkoferstr 8a, D-80336 Munich, Germany. griese@pk-i.med.uni-muenchen.de
European Journal of Medical Research
|April 21, 2001
Summary
Surfactant proteins SP-D and SP-A, key lung immune components, are variably present in sputum and lose their carbohydrate-binding function in larger airways. This impacts their role in innate immunity beyond the peripheral lung.
Area of Science:
- Immunology
- Pulmonology
- Biochemistry
Background:
- Surfactant proteins SP-D and SP-A are collectins crucial for peripheral lung innate immunity.
- They bind microbial carbohydrates, aiding pathogen clearance.
- Their function and concentration in larger airways remain largely unknown.
Purpose of the Study:
- To investigate the presence and functional capacity of SP-D and SP-A in sputum from larger airways.
- To assess the utility of sputum for characterizing these collectins.
Main Methods:
- Induced sputum from healthy adults and spontaneous sputum from cystic fibrosis patients were collected.
- ELISA and carbohydrate binding assays quantified SP-D and SP-A in sputum plugs and sol-fractions.
- Assay conditions (salt, detergent, calcium) were varied.
Main Results:
- SP-D and SP-A were detected in approximately 50% of sputum plugs.
- Detected collectins exhibited zero carbohydrate binding capacity.
- Sputum sol fraction and LPS inhibited collectin binding in a calcium-dependent manner.
- Collectin presence in sputum was variable, unlike their abundance in peripheral lungs.
Conclusions:
- SP-D and SP-A are inconsistently found in sputum from larger airways.
- Their carbohydrate binding capacity is lost in this compartment.
- Sputum may not be a reliable indicator for assessing collectin function in the larger airways.