Surfactant Protein D ELISA Assay
The Surfactant Protein D ELISA Assay is For Research Use Only
Size: 12×8 wells
Sensitivity: 4.153ng/ml
Standard Range: 40-640ng/ml
Incubation Time: 70 minutes
Sample Type: Serum, cell culture supernatant and plasma
Sample Size: 40 ul
Alternative Name: SPD, SP-D
Assay Background
Human Surfactant Protein D (SP-D), homotrimeric protein, is a member of the collageneous subfamily of glycoproteins and calcium-dependent lectins, SP-D is synthesized and secreted by two types of non-ciliated epithelial cells in the peripheral airway, and is also expressed by various epithelial cells in the gastrointestinal and genito-urinary tracts and placenta. SP-D plays an role in the innate response of the body to inhaled pathogens. It aggregates bacteria and viruses, leukocyte function and stimulates an allergenic response. Studies have also shown that SP-D binds to T cells, inhibiting their proliferation. Its binding with inflammatory ligands via protein-protein interactions is effective in reducing specific inflammation. In addition, SP-D binds to apoptotic cells and stimulates their phagocytosis by macrophages governed by mechanisms dependent and CD91 calreticulin. Given that SP-D participates in the immune response, variation in expression of SP-D is linked to several pulmonary diseases.
Sample Preparation and Storage:
Specimens should be clear and non-hemolyzed. Samples should be run at a number of dilutions to ensure accurate quantitation.
- Extract as soon as possible after specimen collection as per relevant procedure. The samples should be tested as soon as possible after the extraction. Alternately the extracted samples can be kept in -20°C. Avoid repeated freeze-thaw cycles.
- Serum- Coagulate at room temperature for 10-20 minutes; centrifuge for 20-min at 2000-3000 rpm. Remove the supernatant. If precipitation appears, recentrifuge.
- Plasma- Use EDTA or citrate plasma as an anticoagulant, mix for 10-20 minutes; centrifuge for 15-min at 2000-3000 rpm. Remove the supernatant carefully. If precipitation appears, recentrifuge.
- Urine- Collect urine in a sterile container, centrifuge for 20-min at 2000-3000 rpm. Remove the supernatant. If precipitation appears, recentrifuge.
- Cell Culture Supernatant- Collect sample in a sterile container. Centrifuge for 20-mins at 2000-3000 rpm. Remove the supernatant carefully. When examining the components within the cell, dilute cell suspension with PBS (pH 7.2-7.4), if cell concentration is greater than 1 million/ml. Damage the cells by repeated freeze-thaw cycles to release intracellular components. Centrifuge for 20-min at 2000-3000 rpm. If precipitation appears, centrifuge again.
- Tissue Samples- Rinse tissues in PBS (pH 7.4) to remove excess blood thoroughly and weigh before homogenization. Mince tissues and homogenize them in PBS (pH7.4) with a glass homogenizer on ice. Thaw at 2-8°C or freeze at -20°C. Centrifuge at 2000-3000 RPM for approximately 20 minutes and collect the supernatant carefully.
Note: Grossly hemolyzed samples are not suitable for use in this assay
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