SPD ELISA Kit (Surfactant Associated Protein D)

Full Name: SPD ELISA Kit (Surfactant Associated Protein D)
Reactivity: Human
Sample Type: Biological Fluids, Tissue Homogenates, Plasma, Serum
Sensitivity: 0.938 ng/ml


Surfactant associated protein D (SPD) belongs to the collectin family of proteins, it is described as a lung surfactant protein. It is made up of three subunits that can be assembled to generate a homotrimer, the 3 regions are collagenous region (N-terminal), nucleating neck region and the lectin domain (C-terminal). It is linked to lung cancer and other respiratory diseases, the agent that contributes to these diseases is thought to be a reactive nitrogen species. This is the gene encoding the protein associated with lung disease caused by reactive nitrogen species.

Some of the functions of SPD include innate immune defence, anti-microbial effects and dampening of the inflammatory process. It is found to be predominately localised on the lung and non-pulmonary tissues. It is also linked to many other external and luminal surfaces such as tears, plasma, amniotic fluid, urine and cerebrospinal fluid.

The SPD structure is a dimer with helices A and B folding into sheets that are each connected by antiparallel β-sheets. Each sheet contains eight α-helices that are folded into loops. Loop 1 has a conserved sequence of Phe/Pro/Ser, loop 2 has an Asp/Glu/Asn sequence and loop 3 has an Arg/Gly/Arg sequence. All three loops contain hydrophobic amino acids to accommodate the membrane.


Human SPD ELISA kit can detect levels of pulmonary surfactant associated protein D (SPD, SFTPD, Collectin-7, lung surfactant protein D, COLEC7) using human samples of tissue homogenates, other biological samples, serum and plasma.


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-SPD 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.


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

Standard Curve: 0, 1.563, 3.125, 6.25, 12.5, 25, 50, 100 ng/ml.
Reactivity: Human
Sensitivity: 0.938 ng/ml
Range: 1.563 – 100 ng/ml
Principle: Sandwich
Application: Research Use Only.


– Specificity: Highly specific for SPD, no cross reactivity or interference between SPD and analogues was detected.
– Recovery: Serum (88 – 104%), EDTA Plasma (88 – 100%), Heparin Plasma (86 – 103%).
– Linearity: Serum (89 – 98%), EDTA Plasma (84 – 95%), Heparin Plasma (87 – 97%).
– Precison Intra-Assay: CV < 8%.
– Precison Inter-Assay: CV < 10%.
– Stability: Less than 10%.


  1. The Role of Surfactant in Lung Disease and Host Defense against Pulmonary Infections. Ann Am Thorac Soc. (2015) 12 (5): 765-74. Han S. and Mallampalli R.K.
  2. Human surfactant protein-D (SP-D) binds Mycoplasma pneumoniae by high affinity interactions with lipids. J Biol Chem. (2002) 277 (23): 20379-85. Chiba H., et al.
  3. Surfactant-associated proteins: structure, function and clinical implications. Curr Pediatr Rev. (2014) 10 (2): 162-7. Ketko A.K. and Donn S.M.
  4. Enzyme-linked immunosorbent assay for human pulmonary surfactant protein D. J Immunol Methods. (1994) 173 (2): 157-64. Inoue T., et al.


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