Technical note: measurement of ferritin in bovine milk and its clinical significance.
A quantitative ELISA was developed for bovine milk ferritin with an assay limit of 0.16 ng/mL of bovine spleen ferritin. Ferritin-binding activity was detected in bovine milk samples, and this binding activity was inhibited by increasing ionic strength with the addition of 0.5 M (NH4)2SO4. Heat treatment (60 degrees C, 20 min) of bovine milk in the presence of 0.5 M (NH4)2SO4 resulted in a 15 to 58% increase in ferritin concentrations compared with untreated samples. Although the recovery of bovine spleen ferritin added to milk was still low (55 to 90%), even in the presence of increased ionic strength with 0.5 M (NH4)2SO4, recovery was improved by heat treatment at 60 degrees C for 20 min (92 to 95%). Milk ferritin concentrations in 30 milk samples from quarters of 25 cows with mastitis (mean +/- SE: 134.2 +/- 28.7 ng/mL) were significantly higher than those in 17 quarter milk samples from 17 noninfected lactating cows (7.2 +/- 1.2 ng/mL), suggesting that bovine milk contains putative ferritin-binding proteins that inhibit immunoassay for milk ferritin and that bovine milk ferritin is an indicator of IMI.
Orino
K
K
Laboratories of Biochemistry, School of Veterinary Medicine and Animal Sciences, Kitasato University, Aomori 034-8628, Japan. orino@vmas.kitasato-u.ac.jp
Watanabe
S
S
Ohtsuka
H
H
Kohiruimaki
M
M
Watanabe
K
K
D000645:Ammonium Sulfate / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000378:metabolism; D016022:Case-Control Studies; D002417:Cattle; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D005293:Ferritins / Q000032:analysis* / Q000502:physiology*; D006358:Hot Temperature; D007774:Lactation / Q000502:physiology; D008414:Mastitis, Bovine / Q000175:diagnosis* / Q000503:physiopathology; D008892:Milk / Q000737:chemistry*; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology
D000906:Antibodies; D005293:Ferritins; D000645:Ammonium Sulfate