SPA ELISA Kit (Pulmonary Surfactant Associated Protein A)

INTENDED USE

Human SPA ELISA kit can measure concentrations of pulmonary surfactant associated protein A (SPA, SFPA1, COLEC4, PSAP, SP-A, collectin-4, alveolar proteinosis protein) present is plasma, serum, biological fluids or tissue homogenate samples. This assay has a minimum sensitivity detection limit of 9.375 pg/ml.

INTRODUCTION

Surfactant protein A (SPA) refers to a large multimeric collectin and C-type lectin important for pulmonary immune defenses and surfactant homeostasis regulating surface tension in the alveoli air-liquid interface. As part of the surfactant layer coating alveolar surfaces, SPA participates in complex organizational dynamics while additionally functioning as an opsonin mediating pathogen interactions with patrolling alveolar macrophages. Thereby it holds duties spanning biophysical surfactant functionality and host immunity intrinsic to lung health.

As the most abundant surfactant apoprotein by mass, SPA integrates into the layer-structured film via its collagen-like N-terminal domain while the globular C-type lectin domain interacts with resident alveolar macrophages and inhaled microbes. By binding carbohydrates on bacterial, fungal and viral pathogens, it acts as opsonin to enhance phagocytic clearance as part of early innate lung defenses. Additionally, SPA interacts with various immune cell receptors to modulate downstream inflammation both activating and suppressing effects contingent on specific signaling contexts. Hence, it sits at the crux coordinating surfactant structure-function dynamics and immune tolerogenicity necessary within continuously ventilated delicate alveoli.

However, leakage of SPA into systemic circulation signifies lung injury as levels increase in settings of infection, inflammation and permeability disruption. Furthermore, deficiency in functional SPA arises in certain genetic disorders and respiratory distress syndrome in premature infants due to inadequate surfactant processing. This compromises both surface-tension lowering biophysical functionality as well as immune defenses heightening risks in these vulnerable populations.

CONTENT

All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

• One 96-Well Plate: Pre-coated with anti-SPA antibody.
• Standards: Lyophilized recombinant.
• Sample/Standard Dilution Buffer.
• Biotinylated-labelled Antibody.
• Antibody Dilution Buffer.
• HRP-Streptavidin Conjugate (SABC).
• SABC Dilution Buffer.
• TMB Substrate.
• Wash Buffer (25x).
• Plate Sealer.
• Product Instructions.

TYPICAL RESULTS

For this SPA ELISA kit, it is recommended that a standard curve is generated for each assay carried out.

Standard Curve: 0, 15.625, 31.25, 62.5, 125, 250, 500, 1000 pg/ml.
Reactivity: Human
Sensitivity: 9.375 pg/ml
Range: 15.625 – 1000 pg/ml
Principle: Sandwich, Double Antibody
Application: Research Use Only.

ASSAY CHARACTERISTICS

– Specificity: Highly specific for SPA, no cross reactivity or interference between SPA and analogues was detected.
– Recovery: Serum (89 – 102%), EDTA Plasma (90 – 98%), Heparin Plasma (93 – 103%).
– Linearity: Serum (85 – 103%), EDTA Plasma (82 – 101%), Heparin Plasma (80 – 95%).
– Precison Intra-Assay: CV < 8%
– Precison Inter-Assay: CV < 10%

REFERENCES

1. Surfactant protein A: A key player in lung homeostasis. Int J Biochem Cell Biol. (2016) 81 (Pt A): 151-155. Nathan N., et al.
2. Native supramolecular protein complexes in pulmonary surfactant: Evidences for SP-A/SP-B interactions. J Proteomics. (2019) 207: 103466. Martínez-Calle M., et al.
3. Alteration of surfactant protein A expression in renal cell carcinoma. Biotech Histochem. (2018) 93 (7): 519-525. Bassorgun CI., et al.

ADDITIONAL INFORMATION

• Full Name: SPA ELISA Kit (Pulmonary Surfactant Associated Protein A)
• Reactivity: Human
• Sample Type: Plasma, Tissue Homogenates, Serum, Biological Fluids
• Sensitivity: 9.375 pg/ml

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