Surfactant Protein A Human ELISA

Summary

Surfactant protein A (SP-A; surfactant- associated protein A – SFTPA; pulmonary surfactant- associated protein A – PSPA) is the major protein component of the lung surfactant in mammals. It belongs, together with SP-D, to the collectins’ family, due to its C-type lectin domain and the collagen-like N-terminal triple helix. The lectin domain mediates the interaction between a collectin and a wide variety of pathogens. The oligomeric structure of SP-A comprises two types of polypeptide chains: SP-A1 and SP-A2 transcribed from sftpa1 and sftpa2 genes. Six trimers of SP-A form its complete octadecameric structure. Human SP-A is expressed primarily in the lung, mostly in alveolar type II cells and also in non-ciliated bronchial epithelial cells. SP-A mRNA can be detected in fetal lung cells after only 20 weeks of gestation. SP-A has been found in various biological fluids, such as bronchoalveolar lavage fluid, sputum, serum, amniotic fluid and vaginal lavage fluid. It has also been found to be expressed in cells of the small and large intestine. SP-A is considered to be an important host defence components against respiratory allergens and pathogens. SP-A takes part in modulating the function of immune system cells – especially dendritic cells and T-cells. Many studies have shown that inflammatory mediators (e.g. TNF) are controlled by SP-A, both positively and negatively. Changes in SP-A production in the lung or its baseline concentrations in serum might be associated with progression or mortality at idiopatic pulmonary fibrosis (IPF). Reduced levels of SP-A in alveolar fluid were also reported in other pulmonary diseases, e.g. acute respiratory distress syndrome (ARDS). Furthermore, elevated levels of SP-A in lungs have been observed in pulmonary alveolar proteinosis (PAP).

Features

• It is intended for research use only
• The total assay time is less than 4 hours
• The kit measures total surfactant protein A in serum, plasma (citrate, heparin), bronchoalveolar lavage fluid and amniotic fluid
• Assay format is 96 wells
• Quality Controls are human serum based. No animal sera are used
• Standard is native protein based
• Components of the kit are provided ready to use, concentrated or lyophilized

Research topic

Immune Response, Infection and Inflammation

Assay format

Sandwich ELISA, Biotin-labelled antibody

Applications

Amniotic fluid, Bronchoalveolar lavage, Plasma-Citrate, Plasma-Heparin, Serum

Sample requirements

10 µl/well

Calibration Curve

Calibration range

1 to 50 ng/ml

Limit of detection

0.16 ng/ml

Intra-assay (Within-Run, n=8)

CV = 4.00 %

Inter-assay (Run-to-Run, n=8)

CV = 9.5 %

Spiking Recovery

98.4 %

Dilution Linearity

102.0 %

Cross-Reactivity

References to summary

• Abe S, Kuroki Y, Shiratori M, Shibuya Y, Kurokawa K, Murakami S, Koba H, Fujishima T, Takahashi H. Serum surfactant proteins A and D as prognostic factors in idiopathic pulmonary fibrosis and their relationship to disease extent. Am J Respir Crit Care Med. 2000 Sep;162 (3 Pt 1):1109-14
• Hudson LD, Nagae H, Kuroki Y, Akino T, Whitsett JA, Hull W, Wong WB, Caldwell E, Ruzinski JT, Steinberg KP, Wright JR, Greene KE, Martin TR. Serial changes in surfactant-associated proteins in lung and serum before and after onset of ARDS. Am J Respir Crit Care Med. 1999 Dec;160 (6):1843-50
• Madan T, Reid KB, Bernal AL, Kamran MF, Ghai R, Shrive AK, Waters P, Greenhough TJ, Kishore U, Chakraborty T. Surfactant proteins SP-A and SP-D: structure, function and receptors. Mol Immunol. 2006 Mar;43 (9):1293-315
• Newman LS, Hunninghake GW, Bucher-Bartelson B, Kuroki Y, King TE Jr, Greene KE, Nagae H, Mason RJ. Serum surfactant proteins-A and -D as biomarkers in idiopathic pulmonary fibrosis. Eur Respir J. 2002 Mar;19 (3):439-46
• Nicholas TE, Bersten AD, Doyle IR. Surfactant proteins-A and -B are elevated in plasma of patients with acute respiratory failure. Am J Respir Crit Care Med. 1997 Oct;156 (4 Pt 1):1217-29
• Nishitani C, Takahashi M, Kuroki Y. Pulmonary collectins in innate immunity of the lung. Cell Microbiol. 2007 Aug;9 (8):1871-9
• Schwarz MI, Kervitsky A, Ix JH, McCormack FX, Brown KK, Kinder BW, King TE Jr. Serum surfactant protein-A is a strong predictor of early mortality in idiopathic pulmonary fibrosis. Chest. 2009 Jun;135 (6):1557-63
• Selman M, Pardo A, Carrillo G, Mejia M, Umstead TM, Phelps DS. Increased surfactant protein-A levels in patients with newly diagnosed idiopathic pulmonary fibrosis. Chest. 2004 Feb;125 (2):617-25
• Steinhilber W, Rivas G, Sanchez-Barbero F, Casals C. Structural and functional differences among human surfactant proteins SP-A1, SP-A2 and co-expressed SP-A1/SP-A2: role of supratrimeric oligomerization. Biochem J. 2007 Sep 15;406 (3):479-89
• Velcovsky HG, Morr H, Grimminger F, Siebert C, Rosseau S, Guth C, Yabut-Perez M, Nix F, Schmidt R, Gunther A, Seeger W. Surfactant abnormalities in idiopathic pulmonary fibrosis, hypersensitivity pneumonitis and sarcoidosis. Eur Respir J. 1999 Sep;14 (3):565-73
• Williams KL, Wright JR, Pastva AM. Immunomodulatory roles of surfactant proteins A and D: implications in lung disease. Proc Am Thorac Soc. 2007 Jul;4 (3):252-7
• Wright JR. Immunoregulatory functions of surfactant proteins. Nat Rev Immunol. 2005 Jan;5 (1):58-68

By research topic:

• Immune Response, Infection and Inflammation

By molecule:

• Surfactant Protein A

Registration form