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Fel d 1 and Fel d 4 levels in cat fur, saliva, and urine

2018; Elsevier BV; Volume: 142; Issue: 6 Linguagem: Inglês

10.1016/j.jaci.2018.07.033

1097-6825

Suzanne Kelly, Jacob Karsh, Jennifer Marcelo, Douglas Boeckh, Nate Stepner, Bryan Santone, Jimmy Yang, William H. Yang,

Contact Dermatitis and Allergies

Cats are popular household pets and commonly cause allergies. Several cat allergens have been identified, including Fel d 1, an uteroglobin. More commonly, animal allergens are lipocalins, and the cat lipocalin allergen Fel d 4 has been identified.1Smith W. Butler A.J. Hazell L.A. Chapman M.D. Pomes A. Nickels D.G. et al.Fel d 4, a cat lipocalin allergen.Clin Exp Allergy. 2004; 34: 1732-1738Crossref PubMed Scopus (102) Google Scholar Recently, Fel d 1– and Fel d 4–specific IgE was assessed in patients with pet allergy.2Ukleja-Sokolowska N. Gawronska-Ukleja E. Zbikowska-Gotz M. Socha E. Lis K. Sokolowski L. et al.Analysis of feline and canine allergen components in patients sensitized to pets.Allergy Asthma Clin Immunol. 2016; 12: 61Crossref PubMed Scopus (25) Google Scholar Of those with cat allergy, 94% had increased levels (>0.35 kU/L) of Fel d 1, and 49% had increased levels of Fel d 4. Older studies cited by Zahradnik and Raulf3Zahradnik E. Raulf M. Animal allergens and their presence in the environment.Front Immunol. 2014; 5: 76Crossref PubMed Scopus (85) Google Scholar reported that Fel d 1 is produced in sebaceous and salivary glands and can be extracted from fur, skin, and saliva.4Anderson M.C. Baer H. Ohman Jr., J.L. A comparative study of the allergens of cat urine, serum, saliva, and pelt.J Allergy Clin Immunol. 1985; 76: 563-569Abstract Full Text PDF PubMed Scopus (52) Google Scholar Intact male cats were found to have more fur Fel d 1 than female cats. There appears to be no information on age- or breed-related differences in Fel d 1 nor is there information about sites of Fel d 4 production. Therefore Fel d 1 and Fel d 4 levels in fur, urine, and saliva were evaluated and compared in a cohort of domestic cats to determine which phenotypes would distinguish cats with higher levels of either antigen. This study was performed in collaboration with a local cat hospital and enrolled cats undergoing routine procedures requiring anesthesia. Canadian Council on Animal Care guidelines were followed. After obtaining the owners' consent, a mixed cohort of 26 male and female cats older than 5 months that were neutered and intact and of different breeds was recruited. Cats with dental (abscess or cavity) or skin diseases or other health problems were excluded. Samples of 100 mg or more fur cut close to the skin by using clippers were collected from either front leg at the site of anesthesia administration. Before use of anticholinergic medication and after anesthesia, 0.25 to 0.50 mL of saliva was pipetted from the cheek pouches. Approximately 2.5 mL of urine was collected by means of catheterization performed by a veterinarian or delegate. For analysis, fur samples were placed in clean plastic bags, stored at 4°C, and shipped at room temperature. Saliva and urine were placed in sterile cryovials, stored at −20°C, and shipped in dry ice. Fel d 1 and Fel d 4 were eluted, 3 aliquots from each sample were analyzed by means of ELISA, and the average was reported (Indoor Biotechnologies, Charlottesville, Va). Medians and ranges were calculated. Comparisons were made with a nonparametric test (Mann-Whitney). There was no attempt to account for multiple comparisons. The 26 cats studied came to the clinic for procedures that required anesthesia, mainly dentistry and spaying (see Table E1 in this article's Online Repository at www.jacionline.org). They were 5 months to 12 years old, half were female, about half were of the domestic short-hair variety, and the majority (65%) had been neutered. Fur was collected from 26 cats, urine was collected from 20 cats, and saliva was collected was from 17 cats. No adverse events were recorded from sample collection. Fel d 1 and Fel d 4 levels in fur, urine, and saliva are shown in Fig 1. In fur, Fel d 1 levels (median, 12.24 μg/g; range, 5.49-20.72 μg/g) were significantly greater than Fel d 4 levels (median, 0.09 μg/g; range, 0.03-0.19 μg/g; P < .001). Conversely, Fel d 4 levels were greater than Fel d 1 levels in saliva (median of 7.62 μg/mL [range, 1.41-17.42 μg/mL] vs 2.45 μg/mL [0.87-5.11 μg/mL], respectively; P = .039). In urine, Fel d 1 (median, 0.02 μg/mL; range, 0.065-0.071 μg/mL) and Fel d 4 levels (<0.4 μg/mL, the limit of detection) were low. The effect of sex and neutering on Fel d 1 and Fel d 4 levels is shown in Table I. In fur both antigens were unrelated to sex and neutering. In saliva there was a potential reciprocal relationship between Fel d 1 and Fel d 4 in neutered and nonneutered animals; however, the numbers were small, and only Fel d 4 levels in neutered female animals were significant (P = .039).Table IFel d 1 and Fel d 4 levels in fur and saliva according to sex and neuteringFel d 1, median (25th-75th percentile)Fel d 4, median (25th-75th percentile)Fur (μg/g) All female cats (n = 13)10.08 (4.3-16.13)0.12 (0.04-0.21) Neutered female cats (n = 7)10.1 (4.0-14.03)0.05 (0.03-0.15) Nonneutered female cats (n = 6)10.1 (6.8-34.7)0.22 (0.21-0.42) All male cats (n = 13)12.72 (8.7-37.35)0.08 (0.02-0.12) Neutered male cats (n = 10)10.89 (6.95-33.11)0.09 (0.06-0.12) Nonneutered male cats (n = 3)14.5 (13.6-37.97)0.02 (0.01-0.12)Saliva (μg/mL) All female cats (n = 10)3.3 (0.83-6.86)9.71 (3.32-16.95) Neutered female cats (n = 5)0.59 (0.22-2.22)17.42 (11.79-19.56)∗P = .039. Nonneutered female cats (n = 5)5.01 (3.67-7.93)2.2 (0.79-6.71)∗P = .039. All male cats (n = 7)3.30 (1.46-4.84)6.71 (1.32-19.71) Neutered male cats (n = 5)3.3 (1.46-4.84)1.41 (1.22-12.04) Nonneutered male cats (n = 2)0.76 (0.41-1.10)17.05 (11.88-22.21)In fur Fel d 1 levels exceeded Fel d 4 levels, and there were no differences based on sex or neutering. In saliva Fel d 4 levels exceeded Fel d 1 levels, and there appeared to be a reciprocal relation between Fel d 1 and Fel d 4 levels based on neutering, which was significant only for neutered versus nonneutered female cats.∗ P = .039. Open table in a new tab In fur Fel d 1 levels exceeded Fel d 4 levels, and there were no differences based on sex or neutering. In saliva Fel d 4 levels exceeded Fel d 1 levels, and there appeared to be a reciprocal relation between Fel d 1 and Fel d 4 levels based on neutering, which was significant only for neutered versus nonneutered female cats. There were no age-related differences in either Fel d 1 or Fel d 4 levels in fur or saliva (see Fig E1 in this article's Online Repository at www.jacionline.org), even though the youngest cats were not neutered. Hair length was used as a surrogate for breed in this study, and although fur Fel d 1 levels were greatest in short-hair cats (15.32 vs 9.22 μg/g and 5.2 μg/g for long- and medium-hair cats, respectively), statistical significance was not reached (see Table E2 in this article's Online Repository at www.jacionline.org). This study confirms earlier findings that Fel d 1 is present in cat fur and saliva and extends this observation to Fel d 4. Furthermore, the data suggest that saliva is the main source of Fel d 4. Given the low fur levels of Fel d 4, it is likely deposited during grooming rather than from sebaceous secretions, as with Fel d 1. Urine is not a significant source of Fel d 1 (0.02 μg/mL). However, levels were greater in the 3 intact male cats (median of 5.15 μg/mL [range, 4.12-7.69 μg/mL] vs 0.013 [range, 0.007-0.026 μg/mL], P = .012), making it possible for litter boxes to be a source of this allergen in the home. Lipocalins represent the largest group of mammalian inhalant allergens.5Virtanen T. Kinnunen T. Rytkonen-Nissinen M. Mammalian lipocalin allergens—insights into their enigmatic allergenicity.Clin Exp Allergy. 2012; 42: 494-504Crossref PubMed Scopus (52) Google Scholar The lipocalin superfamily includes allergens, such as Fel d 4, the major dog allergen Can f 1, and the mouse major urinary protein Mus m 1. These and others have been identified in salivary glands or saliva6Konieczny A. Morgenstern J.P. Bizinkauskas C.B. Lilley C.H. Brauer A.W. Bond J.F. et al.The major dog allergens, Can f 1 and Can f 2, are salivary lipocalin proteins: cloning and immunological characterization of the recombinant forms.Immunology. 1997; 92: 577-586Crossref PubMed Scopus (132) Google Scholar, 7Torres J.A. de Las Heras M. Maroto A.S. Vivanco F. Sastre J. Pastor-Vargas C. Molecular and immunological characterization of the first allergenic lipocalin in hamster: the major allergen from Siberian hamster (Phodopus sungorus).J Biol Chem. 2014; 289: 23382-23388Crossref PubMed Scopus (16) Google Scholar, 8Thavathiru E. Jana N.R. De P.K. Abundant secretory lipocalins displaying male and lactation-specific expression in adult hamster submandibular gland. cDNA cloning and sex hormone-regulated repression.Eur J Biochem. 1999; 266: 467-476Crossref PubMed Scopus (23) Google Scholar and urine3Zahradnik E. Raulf M. Animal allergens and their presence in the environment.Front Immunol. 2014; 5: 76Crossref PubMed Scopus (85) Google Scholar, 7Torres J.A. de Las Heras M. Maroto A.S. Vivanco F. Sastre J. Pastor-Vargas C. Molecular and immunological characterization of the first allergenic lipocalin in hamster: the major allergen from Siberian hamster (Phodopus sungorus).J Biol Chem. 2014; 289: 23382-23388Crossref PubMed Scopus (16) Google Scholar of several species. Our observation that Fel d 4 is present in cat saliva is consistent with these observations. Salivary Fel d 4 levels appeared to be greater in neutered than intact female cats and in intact compared with neutered male cats (Table I); only the former was statistically significant. Expression of another salivary lipocalin, male-specific submandibular gland protein, can be hormonally controlled and is increased in neutered female hamsters.8Thavathiru E. Jana N.R. De P.K. Abundant secretory lipocalins displaying male and lactation-specific expression in adult hamster submandibular gland. cDNA cloning and sex hormone-regulated repression.Eur J Biochem. 1999; 266: 467-476Crossref PubMed Scopus (23) Google Scholar This might also be true for cat salivary Fel d 4. Sex-related differences in fur Fel d 1 levels were not seen (Table I), likely because 10 of 13 male cats were castrated. The 3 intact male cats at 5, 6, and 12 months of age were sexually mature. However, only the 6-month-old had increased fur Fel d 1 levels (61.44 μg/g). Therefore the data do not confirm or refute previous reports that intact male cats have greater fur Fel d 1 levels. It is a common belief that certain cat breeds are hypoallergenic. Hair length as a surrogate for breed did not explain differences in Fel d 1 levels. Siebers et al9Siebers R. Healy B. Holt S. Peters S. Crane J. Fitzharris P. Fel d 1 levels in domestic living rooms are not related to cat color or hair length.J Allergy Clin Immunol. 2001; 108: 652-653Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar also found that sex, fur color, and fur length were not related to Fel d 1 levels in reservoir dust from homes. Although 23% of cats had fur Fel d 1 levels of greater than 30 μg/g in this study, it is possible that other factors, such as day-to-day variation or lack of grooming, might have led to these higher levels. In conclusion, we observed cat-to-cat variability of Fel d 1 levels in fur of domestic cats unrelated to breed, sex, or age. This is contrary to other observations for Fel d 1.3Zahradnik E. Raulf M. Animal allergens and their presence in the environment.Front Immunol. 2014; 5: 76Crossref PubMed Scopus (85) Google Scholar The data suggest that hormonal status can affect salivary Fel d 4 levels in female cats and urinary Fel d 1 levels in male cats. These findings deserve further investigation. In addition, it would be of interest to compare levels of Fel d 4 and Fel d 1 in homes with cats. Given the low levels of Fel d 4 in cat fur, it is likely that levels in houses will also be low but might be still be sufficient to induce levels of specific IgE in patients with cat allergy. Table E1Cat demographic dataSex Male13 Female13Age (y) Mean (SD)5.6 (4.3) Minimum0.42 Maximum12Weight (kg) Mean (SD)4.54 (1.46) Minimum2.47 Maximum7.53Breed (no.) Domestic short hair14 Domestic medium hair3 Domestic long hair9Neutered (no.) Yes17 No9Procedures (no.) Dental cleaning10 Spaying9 Tests∗Tests include biopsy, blood draw, and imaging.5 Ear cyst removal1 Grooming1Twenty-six cats were enrolled in the study. The cats were mostly adults and neutered. They were anesthetized for the procedures, which were predominantly spaying and dental cleaning.∗ Tests include biopsy, blood draw, and imaging. Open table in a new tab Table E2Fur Fel d 1 and Fel d 4 levels show no relation to hair length on a per-gram basisFel d 1 (μg/g)Fel d 4 (μg/g)Domestic short hair (n = 14)15.32 (8.12-46.21)0.12 (0.0225-0.19)Domestic medium hair (n = 3)5.2 (4.04-39.80)0.05 (0.045-0.08)Domestic long hair (n = 9)9.22 (4.0-13.02)0.1 (0.05-0.12) Open table in a new tab Twenty-six cats were enrolled in the study. The cats were mostly adults and neutered. They were anesthetized for the procedures, which were predominantly spaying and dental cleaning.