Human Pulmonary surfactant-associated protein D,SP-D ELISA Kit

Code CSB-E11166h
Size 96T,5×96T,10×96T
Trial Size 24T ELISA kits trial application
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Product Details


The Human Pulmonary surfactant-associated protein D (SP-D) ELISA kit is a sandwich immunoassay specifically designed and validated for the quantitative detection of SP-D in multiple biological solutions, including serum, plasma, bronchoalveolar lavage fluid, or tissue homogenates. It is not intended for diagnostic use. This assay kit was designed and optimized for signal transduction research use in humans. The kit has undergone rigorous quality control in multiple parameters, including sensitivity, specificity, precision, linearity, recovery, and inter-batch difference. Refer to the product instructions for more details.

This assay employs the quantitative sandwich enzyme immunoassay technique, in which SP-D in the samples or standards are sandwiched between pre-coated SP-D antibody and Biotin-conjugated SP-D antibody. HRP-avidin is then added to the wells. Following a wash to remove any unbound reagent, the TMB substrate solution is added to the wells and color develops in proportion to the amount of SP-D bound in the initial step. The color development is stopped upon adding the stop solution, and the intensity of the color is measured at 450 nm via a microplate reader. The levels of SP-D in the samples can be determined by referring to the O.D. (optical density) of the samples to the standard curve.

SP-D is a multimeric collectin involved in innate immune defense. It is expressed in pulmonary and non-pulmonary epithelia. SP-D possesses antimicrobial activity and inhibits inflammation through aggregation and enhancement of phagocytosis of microbes and dying host cells and regulation of host cell responses via cellular receptors. It has been reported that SP-D participates in the development of respiratory diseases including allergic asthma, respiratory distress syndrome, and chronic obstructive pulmonary disease. SP-D leaks from the lung through the induction of disease-caused degradation or modifications and circulatory SP-D is a potential biomarker for lung damage.

Target Name surfactant protein D
Alternative Names COLEC 7 ELISA Kit; COLEC7 ELISA Kit; Collectin-7 ELISA Kit; Collectin7 ELISA Kit; Lung surfactant protein D ELISA Kit; PSP D ELISA Kit; PSP-D ELISA Kit; PSP-D Surfactant protein D ELISA Kit; PSPD ELISA Kit; Pulmonary surfactant apoprotein ELISA Kit; Pulmonary surfactant associated protein D ELISA Kit; Pulmonary surfactant associated protein PSP-D ELISA Kit; Pulmonary surfactant-associated protein D ELISA Kit; SFTP 4 ELISA Kit; SFTP4 ELISA Kit; SFTPD ELISA Kit; SFTPD_HUMAN ELISA Kit; SP D ELISA Kit; SP-D ELISA Kit; Surfactant associated protein pulmonary 4 ELISA Kit; Surfactant protein D ELISA Kit; Surfactant pulmonary associated protein D ELISA Kit
Abbreviation SFTPD
Uniprot No. P35247
Species Homo sapiens (Human)
Sample Types serum, plasma, bronchoalveolar lavage fluid, tissue homogenates
Detection Range 1.25 ng/mL-80 ng/mL
Sensitivity 0.31 ng/mL
Assay Time 1-5h
Sample Volume 50-100ul
Detection Wavelength 450 nm
Research Area Signal Transduction
Assay Principle quantitative
Measurement Sandwich
Intra-assay Precision (Precision within an assay): CV%<8%      
Three samples of known concentration were tested twenty times on one plate to assess.  
Inter-assay Precision (Precision between assays): CV%<10%      
Three samples of known concentration were tested in twenty assays to assess.    
To assess the linearity of the assay, samples were spiked with high concentrations of human SP-D in various matrices and diluted with the Sample Diluent to produce samples with values within the dynamic range of the assay.
  Sample Serum(n=4)  
1:1 Average % 85  
Range % 80-94  
1:2 Average % 96  
Range % 91-100  
1:4 Average % 98  
Range % 92-108  
1:8 Average % 92  
Range % 86-97  
The recovery of human SP-D spiked to levels throughout the range of the assay in various matrices was evaluated. Samples were diluted prior to assay as directed in the Sample Preparation section.
Sample Type Average % Recovery Range  
Serum (n=5) 94 89-97  
EDTA plasma (n=4) 98 90-105  
Typical Data
These standard curves are provided for demonstration only. A standard curve should be generated for each set of samples assayed.
ng/ml OD1 OD2 Average Corrected  
80 2.198 2.068 2.133 2.042  
40 1.457 1.378 1.418 1.327  
20 0.925 0.884 0.905 0.814  
10 0.600 0.578 0.589 0.498  
5 0.410 0.393 0.402 0.311  
2.5 0.255 0.251 0.253 0.162  
1.25 0.136 0.134 0.135 0.044  
0 0.092 0.090 0.091    
Materials provided
  • A micro ELISA plate --- The 96-well plate has been pre-coated with an anti-human SP-D antibody. This dismountable microplate can be divided into 12 x 8 strip plates.
  • Two vials lyophilized standard ---Dilute a bottle of the standard at dilution series, read the OD values, and then draw a standard curve.
  • One vial Biotin-labeled SP-D antibody (100 x concentrate) (120 μl/bottle) ---Act as the detection antibody.
  • One vial HRP-avidin (100 x concentrate) (120 μl/bottle) ---Bind to the detection antibody and react with the TMB substrate to make the solution chromogenic.
  • One vial Biotin-antibodyDiluent (15 ml/bottle) ---Dilute the Biotin-antibody.
  • One vial HRP-avidin Diluent (15 ml/bottle) ---Dilute the HRP-avidin solution.
  • One vial Sample Diluent (50 ml/bottle)---Dilute the sample to an appropriate concentration.
  • One vial Wash Buffer (25 x concentrate) (20 ml/bottle) ---Wash away unbound or free substances.
  • One vial TMB Substrate (10 ml/bottle) ---Act as the chromogenic agent. TMB interacts with HRP, eliciting the solution turns blue.
  • One vial Stop Solution (10 ml/bottle) ---Stop the color reaction. The solution color immediately turns from blue to yellow.
  • Four Adhesive Strips (For 96 wells) --- Cover the microplate when incubation.
  • An instruction manual
Materials not provided
  • A microplate reader capable of measuring absorbance at 450 nm, with the correction wavelength set at 540 nm or 570 nm.
  • An incubator can provide stable incubation conditions up to 37°C±5°C.
  • Centrifuge
  • Vortex
  • Squirt bottle, manifold dispenser, or automated microplate washer
  • Absorbent paper for blotting the microtiter plate
  • 50-300ul multi-channel micropipette
  • Pipette tips
  • Single-channel micropipette with different ranges
  • 100ml and 500ml graduated cylinders
  • Deionized or distilled water
  • Timer
  • Test tubes for dilution
and FAQs
Storage Store at 2-8°C. Please refer to protocol.
Lead Time 3-5 working days


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Target Data

Function Contributes to the lung's defense against inhaled microorganisms, organic antigens and toxins. Interacts with compounds such as bacterial lipopolysaccharides, oligosaccharides and fatty acids and modulates leukocyte action in immune response. May participate in the extracellular reorganization or turnover of pulmonary surfactant. Binds strongly maltose residues and to a lesser extent other alpha-glucosyl moieties.
Gene References into Functions
  1. these findings indicate that the membrane-type surfactant protein D serve as an effective therapeutic strategy for inhibiting macrophage-mediated xenograft rejection in xenotransplantation PMID: 29425774
  2. Assays that can separate SP-D proteolytic breakdown products or modified forms from naturally occurring SP-D trimers may result in optimal disease markers for pulmonary inflammatory diseases PMID: 28960651
  3. the SPA and SPD levels in EBC were correlated with lung function, which contributed to COPD diagnosis. PMID: 28791362
  4. Studied predictive value of surfactant protein D (SP-D) in lung cancer patients with interstitial lung disease induced by anticancer agents (ILD-AA). Results suggest that SP-D level change was a risk factor for mortality in patients with ILD-AA, and that SP-D might be a predictive prognostic biomarker of ILD-AA. PMID: 28464801
  5. SP-D also delays FasL-induced death of primary human T cells. SP-D delaying the progression of the extrinsic pathway of apoptosis could have important implications in regulating immune cell homeostasis at mucosal surfaces PMID: 28168327
  6. Trimeric SP-D wildtype recognized larger LPS inner core oligosaccharides with slightly enhanced affinity than smaller compounds suggesting the involvement of stabilizing secondary interactions. PMID: 27350640
  7. rs2819096 in the surfactant protein D (SFTPD) gene was associated with a higher risk of COPD GOLD III + IV. PMID: 27078193
  8. SP-D increases the formation of nuclear and membrane blebs. Inhibition of caspase-8 confirms the effect of SP-D is unique to the caspase-8 pathway. PMID: 29107869
  9. Findings indicate serum pulmonary surfactant protein D (SP-D, SFTPD) level as a potential marker to estimate the efficacy of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKIs). PMID: 28745320
  10. Patients with SP-D 11Thr/Thr genotype were more susceptible to acute kidney injury (AKI). Compared with healthy controls, serum SP-D levels at day 1, 3 and 7 were significantly elevated in AKI patients. PMID: 28212617
  11. This review intends to provide a current overview of the genetics, structure and extra-pulmonary functions of the surfactant collectin proteins. PMID: 28351530
  12. Meta-analysis found that serum SP-A/D detection might be useful for differential diagnosis and prediction of survival in patients with idiopathic pulmonary fibrosis. PMID: 28591049
  13. The findings suggest that SP-D inhibits LPS-stimulated production of interleukin-12p40 via the SIRPalpha/ROCK/ERK signaling pathway. PMID: 28641719
  14. Efficient lipopolysaccharide recognition by SP-D requires multiple binding interactions utilizing the three major ligand-binding determinants in the SP-D binding pocket, with Ca-dependent binding of inner-core heptose accompanied by interaction of anhydro-Kdo (4,7-anhydro-3-deoxy-d-manno-oct-2-ulosonic acid) with Arg343 and Asp325. PMID: 26953329
  15. SP-D levels in bronchoalveolar lavage samples were significantly lower in severe asthma compared with healthy controls and mild asthma. Serum SP-D was significantly increased in severe asthma compared with healthy controls and mild asthma. PMID: 26836907
  16. Surfactant protein D levels differed among idiopathic pulmonary fibrosis, pulmonary sarcoidosis and chronic pulmonary obstructive disease. PMID: 27758987
  17. Elevated levels of SP-D are Associated with Idiopathic Pulmonary Fibrosis. PMID: 27293304
  18. Data do not support that pSP-D levels influence or reflect the development of subclinical atherosclerosis. However, the data support that SP-D plays a role in the etiology of atherosclerotic disease development. PMID: 26748346
  19. Human and murine data together indicate that SP-A, SP-D and MBL are synthesized in early gestational tissues, and may contribute to regulation of immune response at the feto-maternal interface during pregnancy. PMID: 26603976
  20. Serum SP-D may serve as a convenient medium to distinguish lung infection caused by M. pneumoniae. PMID: 26617840
  21. findings shed new light on the discovery and/or development of a useful biomarker based on glycosylation changes for diagnosing COPD. PMID: 26206179
  22. Quantitative real-time PCR experiments disclosed significantly increased leukocyte NOS2 and SFTPD mRNA levels in hyperglycemic gestational diabetes mellitus patients (P < 0.05). PMID: 26568332
  23. Serum SP-D was not significantly different between patients with connective tissue disease-interstitial lung disease, chronic fibrosing interstitial pneumonia patients and healthy controls. PMID: 26424433
  24. Letter: report higher serum SP-D levels in bird-related hypersensitivity pneumonitis during winter. PMID: 25591150
  25. The SP-D level showed positive correlations with carotid IMT and coronary artery calcification in patients on long-term hemodialysis. PMID: 27012038
  26. SP-D is expressed differently in airways of asthmatics relative to that of non-asthmatics. PMID: 25848896
  27. Sputum and bronchoalveolar lavage fluid SFTPD were significantly higher in patients with severe asthma compared to mild-moderate asthma and healthy controls. PMID: 25728058
  28. We demonstrated for the first time in a Chinese population cohort that genetic polymorphisms of SP-D are not only associated with risk of COPD development, but also related to disease manifestation and that they predict outcomes. PMID: 25376584
  29. In chromium-exposed workers, blood levels of CC16, and CC16/SP-D were lower than in controls. Positive relationships were shown between CC16 or CC16/SP-D and indicators of lung function. PMID: 25851191
  30. In Sjogren's syndrome, high SP-D levels were found in patients with severe glandular involvement, hypergammaglobulinemia, leukopenia, extraglandular manifestations, and positive anti-Ro/La antibodies. PMID: 25362659
  31. Results revealed that higher circulating levels of SP-D are associated with higher mortality risk in critically ill A/H1N1 patients. PMID: 25537934
  32. In idiopathic pleuroparenchymal fibroelastosis SP-D was elevated, while KL-6 was within a normal range. PMID: 24880792
  33. These data suggest that SP-D reduces EGF binding to EGFR through the interaction between the carbohydrate recognition domain of SP-D and N-glycans of EGFR, and downregulates EGF signaling. PMID: 24608429
  34. the multi-faceted role of human SP-D against HIV-1 PMID: 25036364
  35. SFTPD polymorphism is associated with the risk of respiratory outcomes; it may be an essential factor affecting pulmonary adaptation in premature infants PMID: 25015576
  36. Results suggest that Smokers who are carriers of the SFTPD AG and AA polymorphic genotypes may be at a higher risk of developing Chronic obstructive pulmonary disease when compared with wild-type GG genotype carriers. PMID: 24504887
  37. Both mRNA and protein levels of gp340 were significantly higher in patients with biofilm associated chronic rhinosinusitis (CRS) than those with CRS and no biofilm and controls. PMID: 24121782
  38. In this review, we highlight the associations of eosinophilic lung diseases with SP-A and SP-D levels and functions. PMID: 24960334
  39. murine expression of human polymorphic variants does not significantly influence the severity of allergic airway inflammation PMID: 24712849
  40. Genetic disposition for low surfactant protein-D was not associated with rheumatoid arthritis but with erosive rheumatoid arthritis by interaction with smoking. PMID: 24264011
  41. SP-D levels were significantly higher in the sub-massive pulmonary embolism group overall. PMID: 25291941
  42. a novel pathway for the immunomodulatory functions of SP-D mediated via binding of its collagenous domains to LAIR-1. PMID: 24585933
  43. Human surfactant protein D alters oxidative stress and HMGA1 expression to induce p53 apoptotic pathway in eosinophil leukemic cell line. PMID: 24391984
  44. Surfactant protein D substitutions at the 325 and 343 positions (D325A+R343V) exhibit markedly increased antiviral activity for seasonal strains of influenza A virus. PMID: 24705721
  45. SFTPD single-nucleotide polymorphisms, rs1923536 and rs721917, and haplotypes, including these single-nucleotide polymorphisms or rs2243539, were inversely associated with expiratory lung function in interaction with smoking. PMID: 24610936
  46. Increases in serum KL-6 and SP-D levels during the first 4 weeks after starting therapy, but not their levels at any one time point, predict poor prognosis in patients with polymyositis/dermatomyositis. PMID: 22983659
  47. serum SP-D, but not SP-A, levels were significantly higher in the German than in the Japanese cohort PMID: 24400879
  48. Lower oligomeric form of surfactant protein D is associated with cystic fibrosis. PMID: 24120837
  49. Lung permeability biomakers [surfactant protein D (SP-D) and Clara cell secretory protein (CC16) in plasma] and forced expiratory volumes and flow were measured in swimmers in indoor swimming pool waters treated with different disinfection methods. PMID: 23874631
  50. In patients with systemic sclerosis-related interstitial lung disease, surfactant protein D was correlated with forced vital capacity. It was not a longterm prognostic indicator. PMID: 23588945

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Subcellular Location Secreted, extracellular space, extracellular matrix, Secreted, extracellular space, surface film
Protein Families SFTPD family
Tissue Specificity Expressed in lung, brain, pancreas and adipose tissue (mainly mature adipocytes).
Database Links

HGNC: 10803

OMIM: 178635

KEGG: hsa:6441

STRING: 9606.ENSP00000361366

UniGene: Hs.253495


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