This assay employs a two-site sandwich ELISA to quantitate LTF in samples. An antibody specific for LTF has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any LTF present is bound by the immobilized antibody. After removing any unbound substances, a biotin-conjugated antibody specific for LTF is added to the wells. After washing, Streptavidin conjugated Horseradish Peroxidase (HRP) is added to the wells. Following a wash to remove any unbound avidin-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of LTF bound in the initial step. The color development is stopped and the intensity of the color is measured.
 

LTF, a globular multifunctional protein with antimicrobial activity (bacteriocide, fungicide), is part of the innate defense, mainly at mucoses. Lactoferrin is found in milk and many mucosal secretions such as tears and saliva. Lactoferrin is also present in secondary granules of PMN and also is secreted by some acinar cells. Human colostrum has the highest concentration, followed by human milk, then cow milk. Lactoferrin belongs to the transferrin family proteins (TF, melanotransferrin, ovotransferin, etc.). Its molecular mass is 80,000 u (80 kDa).Lactoferrin antimicrobial activity is due partly to its high affinity for Fe (ferric state). LF proteolysis produces lactoferricin, kaliocin-5 small peptides with antimicrobial activity.
 

Reagents	Quantity	Reagents	Quantity
Assay plate (96 Wells)	1	Instruction manual	1
Standard (lyophilized)	2	Sample Diluent	1 x 20 mL
Biotin-Conjugate (concentrate 100 x)	1 x 120 μL	Biotin-Conjugate Diluent	1 x 20 mL
Streptavidin-HRP  (concentrate 100 x)	1 x 120 μL	Streptavidin-HRP Diluent	1 x 20 mL
Wash Buffer (concentrate 25 x)	1 x 20 mL	Substrate Solution	1 x 10 mL
Stop Solution	1 x 10 mL	Adhesive Films	4

 

This assay has high sensitivity and excellent specificity for detection of Bovine LTF. No significant cross-reactivity or interference between Bovine LTF and analogues was observed.
 

Matrices listed below were spiked with certain level of recombinant Bovine LTF and the recovery rates were calculated by comparing the measured value to the expected amount of Bovine LTF in samples.

Sample Type	Number	Recovery range (%)	Average(%)
Serum	10	90-101	96
EDTA plasma	10	89-97	93
Heparin plasma	10	91-99	95

 

Intra-assay Precision (Precision within an assay) Three samples of known concentration were tested twenty times on one plate to assess intra-assay precision. Inter-assay Precision (Precision between assays) Three samples of known concentration were tested in forty separate assays to assess inter-assay precision. CV (%) = SD/meanX100 Intra-Assay: CV<8% Inter-Assay: CV<12%
 

The linearity of the kit was assayed by testing samples spiked with appropriate concentration of Bovine LTF and their serial dilutions. The results were demonstrated by the percentage of calculated concentration to the expected.

Sample Type	1：2	1：4	1：8	1：16
Serum	78-89%	81-99%	92-103%	95-105%
EDTA plasma	91-101%	90-98%	93-101%	91-98%
Heparin plasma	92-103%	93-102%	92-99%	91-101%

 

The stability of ELISA kit is determined by the loss rate of activity. The loss rate of this kit is less than 5% within the expiration date under appropriate storage condition. The loss rate was determined by accelerated thermal degradation test. Keep the kit at 37°C for 4 and 7 days, and compare O.D.values of the kit kept at 37°C with that of at recommended temperature. (referring from China Biological Products Standard, which was calculated by the Arrhenius equation. For ELISA kit, 4 days storage at 37°C can be considered as 6 months at 2 - 8°C, which means 7 days at 37°C equaling 12 months at 2 - 8°C).
 

Serum: Use a serum separator tube (SST) and allow samples to clot for two hours at room temperature or overnight at 2 - 8°C before centrifugation for 15 minutes at 1000 × g. Remove serum and assay immediately or aliquot and store samples at ≤ -20°C. Avoid repeated freeze-thaw cycles. Plasma: Collect plasma using EDTA, or heparin as an anticoagulant. Centrifuge for 15 minutes at 1000 × g at 2 - 8°C within 30 minutes of collection. Assay immediately or aliquot and store samples at ≤ -20°C. Avoid repeated freeze-thaw cycles. Other biological fluids: Centrifuge samples for 20 minutes at 1000 × g. Remove particulates and assay immediately or store samples in aliquot at -20°C or -80°C. Avoid repeated freeze/thaw cycles.
 

Store at 2-8°C. Please refer to Instruction Manual.