Human SLPI Quantikine ELISA Kit

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Human SLPI ELISA Standard Curve
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Product Details
Citations (33)
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Human SLPI Quantikine ELISA Kit Summary

Assay Type
Solid Phase Sandwich ELISA
96-well strip plate
Assay Length
4.5 hours
Sample Type & Volume Required Per Well
Cell Culture Supernates (100 uL), Serum (10 uL), EDTA Plasma (10 uL), Heparin Plasma (10 uL), Citrate Plasma (10 uL), Urine (20 uL)
25 pg/mL
Assay Range
62.5 - 4,000 pg/mL (Cell Culture Supernates, Serum, EDTA Plasma, Heparin Plasma, Citrate Plasma, Urine)
Natural and recombinant human SLPI
< 0.5% cross-reactivity observed with available related molecules.Cross-species reactivity not tested.
No significant interference observed with available related molecules.

Product Summary

The Quantikine Human SLPI Immunoassay is a 4.5 hour solid phase ELISA designed to measure SLPI in cell culture supernates, serum, plasma, and urine. It contains E. coli-expressed recombinant human SLPI and antibodies raised against the recombinant factor. The kit has been shown to accurately quantitate recombinant human SLPI. Results obtained using natural human SLPI showed linear curves that were parallel to the curves obtained using the recombinant kit standards. These results indicate that this kit can be used to determine relative mass values for natural human SLPI.


Intra-Assay Precision (Precision within an assay) Three samples of known concentration were tested on one plate to assess intra-assay precision
Inter-Assay Precision (Precision between assays) Three samples of known concentration were tested in separate assays to assess inter-assay precision

Cell Culture Supernates, Serum, EDTA Plasma, Heparin Plasma, Citrate Plasma, Urine

Intra-Assay Precision Inter-Assay Precision
Sample 1 2 3 1 2 3
n 20 20 20 20 20 20
Mean (pg/mL) 109 693 2026 188 1174 2157
Standard Deviation 8.7 37.1 84.1 15.1 57.5 123
CV% 8 5.4 4.2 8 4.9 5.7


The recovery of SLPI was determined in various matrices by mixing high dose samples with low dose samples in ratios of 1:2, 1:1, and 2:1.

Sample Type Average % Recovery Range %
Cell Culture Media (n=5) 94 84-105
Citrate Plasma (n=10) 97 92-102
EDTA Plasma (n=10) 96 87-103
Heparin Plasma (n=10) 106 98-116
Serum (n=10) 98 89-104
Urine (n=25) 98 92-103


To assess the linearity of the assay, the following biological samples containing, or spiked with high concentrations of SLPI, were diluted with Calibrator Diluent and then assayed.
Human SLPI ELISA Linearity

Scientific Data

Human SLPI ELISA Standard Curve

Product Datasheets

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Preparation and Storage

The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.
Store the unopened product at 2 - 8 °C. Do not use past expiration date.

Background: SLPI

Secretory leukocyte protease inhibitor (SLPI) is found in various secretory fluids including parotid secretions, bronchial, nasal, cervical mucous, and seminal fluid. SLPI is a potent inhibitor of many proteolytic enzymes including the neutrophil proteases, elastase, cathepsin G, chymotrypsin, and trypsin.

Long Name:
Secretory Leukocyte Protease Inhibitor
Entrez Gene IDs:
6590 (Human); 20568 (Mouse)
Alternate Names:
ALK1; ALPProtease inhibitor WAP4; antileukoproteinase; BLPISeminal proteinase inhibitor; HUSI; HUSI-I; Mucus proteinase inhibitor; secretory leukocyte peptidase inhibitor; secretory leukocyte protease inhibitor (antileukoproteinase); Secretory leukocyte protease inhibitor; SLPI; WAP four-disulfide core domain protein 4; WAP4HUSI-1; WFDC4MPI
⚠ WARNING: This product can expose you to chemicals including N,N-Dimethylforamide, which is known to the State of California to cause cancer. For more information, go to

Assay Procedure

Refer to the product for complete assay procedure.

Bring all reagents and samples to room temperature before use. It is recommended that all samples, standards, and controls be assayed in duplicate.
  1.   Prepare all reagents, standard dilutions, and samples as directed in the product insert.
  2.   Remove excess microplate strips from the plate frame, return them to the foil pouch containing the desiccant pack, and reseal.

  3. 100 µL Assay Diluent
  4.   Add 100 µL of Assay Diluent to each well.

  5. 100 µL Standard, Control, or Sample
  6.   Add 100 µL of Standard, control, or sample to each well. Cover with a plate sealer, and incubate at room temperature for 2 hours.
  7.   Aspirate each well and wash, repeating the process twice for a total of 3 washes.

  8. 200 µL Conjugate
  9.   Add 200 µL of Conjugate to each well. Cover with a new plate sealer, and incubate at room temperature for 2 hours.
  10.   Aspirate and wash 3 times.

  11. 200 µL Substrate Solution
  12.   Add 200 µL Substrate Solution to each well. Incubate at room temperature for 20 minutes. PROTECT FROM LIGHT.

  13. 50 µL Stop Solution
  14.   Add 50 µL of Stop Solution to each well. Read at 450 nm within 30 minutes. Set wavelength correction to 540 nm or 570 nm.

Citations for Human SLPI Quantikine ELISA Kit

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

33 Citations: Showing 1 - 10
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  1. Secretory leukocyte protease inhibitor and risk of heart failure in the Multi-Ethnic Study of Atherosclerosis
    Authors: KT Sawicki, DR Nannini, SJ Bielinski, NB Larson, DM Lloyd-Jone, B Psaty, KD Taylor, SJ Shah, LJ Rasmussen-, JT Wilkins, EM McNally, RB Patel
    Scientific Reports, 2023;13(1):604.
    Species: Human
    Sample Types: Serum
  2. Changes in Microbiome Dominance Are Associated With Declining Lung Function and Fluctuating Inflammation in People With Cystic Fibrosis
    Authors: DL Frey, C Bridson, S Dittrich, SY Graeber, M Stahl, S Wege, F Herth, O Sommerburg, C Schultz, A Dalpke, MA Mall, S Boutin
    Frontiers in Microbiology, 2022;13(0):885822.
    Species: Human
    Sample Types: Sputum
  3. Elevated plasma levels of epithelial and endothelial cell markers in COVID-19 survivors with reduced lung diffusing capacity six months after hospital discharge
    Authors: O Sibila, L Perea, N Albacar, J Moisés, T Cruz, N Mendoza, B Solarat, G Lledó, G Espinosa, JA Barberà, JR Badia, A Agustí, J Sellarés, R Faner
    Respiratory Research, 2022;23(1):37.
    Species: Human
    Sample Types: Plasma
  4. Oral secretory leukocyte protease inhibitor (SLPI): Associations with oropharyngeal cancer and treatment outcome
    Authors: BL Dickey, B Sirak, L Martin-Gom, RR Reich, M Abrahamsen, K Isaacs-Sor, CH Chung, AR Giuliano
    PLoS ONE, 2021;16(7):e0254161.
    Species: Human
    Sample Types: Saliva
  5. Topical Estrogen Treatment Augments the Vaginal Response to Escherichia coli Flagellin
    Authors: A Stanton, C Mowbray, M Lanz, K Brown, P Hilton, A Tyson-Capp, RS Pickard, ASM Ali, J Hall
    Sci Rep, 2020;10(1):8473.
    Species: Human
    Sample Types: Vaginal Fluid
  6. Improved early detection of ovarian cancer using longitudinal multimarker models
    Authors: HJ Whitwell, J Worthingto, O Blyuss, A Gentry-Mah, A Ryan, R Gunu, J Kalsi, U Menon, I Jacobs, A Zaikin, JF Timms
    Br. J. Cancer, 2020;0(0):.
    Species: Human
    Sample Types: Serum
  7. Secretory leukocyte protease inhibitor and progranulin as possible regulators of cervical remodeling in pregnancy
    Authors: T Samejima, T Nagamatsu, N Akiba, T Fujii, S Sayama, K Kawana, A Taguchi, K Kumasawa, T Iriyama, Y Osuga, T Fujii
    J Reprod Immunol, 2020;143(0):103241.
    Species: Human
    Sample Types: Cervical Mucus
  8. Secretory Leukocyte Protease Inhibitor (SLPI)-A Novel Predictive Biomarker of Acute Kidney Injury after Cardiac Surgery: A Prospective Observational Study
    Authors: L Averdunk, C Fitzner, T Levkovich, DE Leaf, M Sobotta, J Vieten, A Ochi, G Moeckel, G Marx, C Stoppe
    J Clin Med, 2019;8(11):.
    Species: Human
    Sample Types: Serum
  9. Endothelial-Cell-Derived Human Secretory Leukocyte Protease Inhibitor (SLPI) Protects Cardiomyocytes against Ischemia/Reperfusion Injury
    Authors: K Kongpol, N Nernpermpi, E Prompunt, S Kumphune
    Biomolecules, 2019;9(11):.
    Species: Human
    Sample Types: Cell culture supernat
  10. High IFN-gamma and low SLPI mark severe asthma in mice and humans.
    Authors: Raundhal M, Morse C, Khare A, Oriss T, Milosevic J, Trudeau J, Huff R, Pilewski J, Holguin F, Kolls J, Wenzel S, Ray P, Ray A
    J Clin Invest, 2015;125(8):3037-50.
    Species: Human
    Sample Types: Cell Culture Supernates
  11. Unexpected Inflammatory Effects of Intravaginal Gels (Universal Placebo Gel and Nonoxynol-9) on the Upper Female Reproductive Tract: A Randomized Crossover Study.
    Authors: Smith-McCune K, Chen J, Greenblatt R, Shanmugasundaram U, Shacklett B, Hilton J, Johnson B, Irwin J, Giudice L
    PLoS ONE, 2015;10(7):e0129769.
    Species: Human
    Sample Types: Complex Sample Type
  12. Hypoxia down-regulates expression of secretory leukocyte protease inhibitor in bronchial epithelial cells via TGF-beta1.
    Authors: Pahlman L, Jogi A, Gram M, Mori M, Egesten A
    BMC Pulm Med, 2015;15(0):19.
    Species: Human
    Sample Types: Cell Culture Supernates
  13. A lack of secretory leukocyte protease inhibitor (SLPI) causes defects in granulocytic differentiation.
    Authors: Klimenkova O, Ellerbeck W, Klimiankou M, Unalan M, Kandabarau S, Gigina A, Hussein K, Zeidler C, Welte K, Skokowa J
    Blood, 2014;123(8):1239-49.
  14. Molecular pathogenesis of post-transplant acute kidney injury: assessment of whole-genome mRNA and miRNA profiles.
    Authors: Wilflingseder J, Sunzenauer J, Toronyi E, Heinzel A, Kainz A, Mayer B, Perco P, Telkes G, Langer R, Oberbauer R
    PLoS ONE, 2014;9(8):e104164.
    Species: Human
    Sample Types: Plasma
  15. Regulation of progranulin expression in human microglia and proteolysis of progranulin by matrix metalloproteinase-12 (MMP-12).
    Authors: Suh HS, Choi N, Tarassishin L, Lee SC
    PLoS ONE, 2012;7(4):e35115.
    Species: Human
    Sample Types: Cell Culture Supernates
  16. The relationship between secretory leukocyte protease inhibitor expression and Epstein-Barr virus status among patients with nasopharyngeal carcinoma.
    Authors: Tse KP, Wu CS, Hsueh C
    Anticancer Res., 2012;32(4):1299-307.
    Species: Human
    Sample Types: Serum
  17. A randomized trial to assess anti-HIV activity in female genital tract secretions and soluble mucosal immunity following application of 1% tenofovir gel.
    Authors: Keller MJ, Madan RP, Torres NM
    PLoS ONE, 2011;6(1):e16475.
    Species: Human
    Sample Types: Vaginal Lavage Fluid
  18. Secretory leukocyte protease inhibitor (SLPI) expression and tumor invasion in oral squamous cell carcinoma.
    Authors: Wen J, Nikitakis NG, Chaisuparat R, Greenwell-Wild T, Gliozzi M, Jin W, Adli A, Moutsopoulos N, Wu T, Warburton G, Wahl SM
    Am. J. Pathol., 2011;178(6):2866-78.
    Species: Human
    Sample Types: Cell Culture Supernates
  19. Bacterial vaginosis, not HIV, is primarily responsible for increased vaginal concentrations of proinflammatory cytokines.
    Authors: Mitchell CM, Balkus J, Agnew KJ, Cohn S, Luque A, Lawler R, Coombs RW, Hitti JE
    AIDS Res. Hum. Retroviruses, 2008;24(5):667-71.
    Species: Human
    Sample Types: Vaginal Fluid
  20. Overexpression of a secretory leukocyte protease inhibitor in human gastric cancer.
    Authors: Cheng WL, Wang CS, Huang YH, Liang Y, Lin PY, Hsueh C, Wu YC, Chen WJ, Yu CJ, Lin SR, Lin KH
    Int. J. Cancer, 2008;123(8):1787-96.
    Species: Human
    Sample Types: Plasma
  21. The secretory leukocyte protease inhibitor (SLPI) and the secondary granule protein lactoferrin are synthesized in myelocytes, colocalize in subcellular fractions of neutrophils, and are coreleased by activated neutrophils.
    Authors: Jacobsen LC, Sorensen OE, Cowland JB, Borregaard N, Theilgaard-Monch K
    J. Leukoc. Biol., 2008;83(5):1155-64.
    Species: Human
    Sample Types: Cell Lysates
  22. Use of an immunoaffinity-mass spectrometry-based approach for the quantification of protein biomarkers from serum samples of lung cancer patients.
    Authors: Nicol GR, Han M, Kim J, Birse CE, Brand E, Nguyen A, Mesri M, FitzHugh W, Kaminker P, Moore PA, Ruben SM, He T
    Mol. Cell Proteomics, 2008;7(10):1974-82.
    Species: Human
    Sample Types: Serum
  23. PRO 2000 elicits a decline in genital tract immune mediators without compromising intrinsic antimicrobial activity.
    Authors: Keller MJ, Guzman E, Hazrati E, Kasowitz A, Cheshenko N, Wallenstein S, Cole AL, Cole AM, Profy AT, Wira CR, Hogarty K, Herold BC
    AIDS, 2007;21(4):467-76.
    Species: Human
    Sample Types: Vaginal Lavage Fluid
  24. Mucosal innate immune factors in secretions from high-risk individuals immunized with a bivalent gp120 vaccine.
    Authors: Cummins JE, Denniston M, Mayer KH, Pickard R, Novak RM, Graham P, Gurwith M, Orelind K, Ackers ML, Dezzutti CS
    AIDS Res. Hum. Retroviruses, 2007;23(5):748-54.
    Species: Human
    Sample Types: Serum
  25. An integrated clinical-genomics approach identifies a candidate multi-analyte blood test for serous ovarian carcinoma.
    Authors: Meinhold-Heerlein I, Bauerschlag D, Zhou Y, Sapinoso LM, Ching K, Frierson H, Brautigam K, Sehouli J, Stickeler E, Konsgen D, Hilpert F, von Kaisenberg CS, Pfisterer J, Bauknecht T, Jonat W, Arnold N, Hampton GM
    Clin. Cancer Res., 2007;13(2):458-66.
    Species: Human
    Sample Types: Serum
  26. Arginine-specific gingipains from Porphyromonas gingivalis deprive protective functions of secretory leucocyte protease inhibitor in periodontal tissue.
    Authors: Into T, Inomata M, Kanno Y, Matsuyama T, Machigashira M, Izumi Y, Imamura T, Nakashima M, Noguchi T, Matsushita K
    Clin. Exp. Immunol., 2006;145(3):545-54.
    Species: Human
    Sample Types: Cell Culture Supernates
  27. Differential proteolytic enzyme activity in eosinophilic and neutrophilic asthma.
    Authors: Simpson JL, Scott RJ, Boyle MJ, Gibson PG
    Am. J. Respir. Crit. Care Med., 2005;172(5):559-65.
    Species: Human
    Sample Types: Sputum
  28. Salivary secretory leukocyte protease inhibitor and oral candidiasis in human immunodeficiency virus type 1-infected persons.
    Authors: Chattopadhyay A, Gray LR, Patton LL, Caplan DJ, Slade GD, Tien HC, Shugars DC
    Infect. Immun., 2004;72(4):1956-63.
    Species: Human
    Sample Types: Saliva
  29. Effect of fluticasone on the elastase:antielastase profile of the normal lung.
    Authors: Kamal AM, Corrigan CJ, Tetley TD, Alaghband-Zadeh J, Smith SF
    Eur. J. Clin. Invest., 2002;32(9):713-9.
    Species: Human
    Sample Types: BALF
  30. Salivary secretory leukocyte protease inhibitor is associated with reduced transmission of human immunodeficiency virus type 1 through breast milk.
    Authors: Farquhar C, VanCott TC, Mbori-Ngacha DA, Horani L, Bosire RK, Kreiss JK, Richardson BA, John-Stewart GC
    J. Infect. Dis., 2002;186(8):1173-6.
    Species: Human
    Sample Types: Saliva
  31. Relationship between airway inflammation and the frequency of exacerbations in patients with smoking related COPD.
    Authors: Gompertz S, á—Óã=ÄV¾WÄ, /&#x0E;@ðtJ‡&#x0C;ã, Bayley DL, Hill SL, Stockley RA
    `„ÞRqp±šú°†0~«Â‹9ê¢ü JÕÈ$GôÏf –4± beta ~lþ8Wúu“ƒ•îçÐ00©Ù °x°Ï*á|øB´Æ‘?+@“ÞQ}¨»9‡m£Íå8¬vT?[A¥±¶Üùæ¨Ü­nU™-™œŠ!Þ‰êÖYí—ÁjyŸÁ}®)¢2A, 2001;56(1):36-41.
    Species: Human
    Sample Types: Saliva
  32. Passive transfer of scrub typhus plasma to patients with AIDS: a descriptive clinical study.
    Authors: Watt G, Kantipong P, Jongsakul K, de Souza M, Burnouf T
    QJM, 2001;94(11):599-607.
    Species: Human
    Sample Types: Plasma
  33. Secretory leukocyte protease inhibitor inhibits infection of monocytes and lymphocytes with human immunodeficiency virus type 1 but does not interfere with transcytosis of cell-associated virus across tight epithelial barriers.
    Authors: Hocini H, Becquart P, Bouhlal H, Adle-Biassette H, Kazatchkine MD, Belec L
    Clin. Diagn. Lab. Immunol., 2000;7(3):515-8.
    Species: Human
    Sample Types: Vaginal Lavage Fluid


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