Partial characterization of feline myeloperoxidase and investigation of its potential role as an autoantigen in hyperthyroid cats.
OBJECTIVE
To partially characterize the cDNA, amino acid sequence, and tertiary structure of feline myeloperoxidase, describe its cellular location in mature granulocytes, and determine whether hyperthyroid cats have anti-myeloperoxidase antibody.


METHODS
Bone marrow RNA and whole blood from cats of various sources and feline serum samples submitted for measurement of total thyroxine concentration from September 2006 to July 2007.


METHODS
Feline myeloperoxidase cDNA was amplified from bone marrow RNA; presumptive splice sites were determined by comparison with human sequences. Intracellular localization of myeloperoxidase in granulocytes was determined by use of immunofluorescence and electron microscopy, and molecular weight and partial tertiary structure were determined by use of immunoblotting of granulocyte lysates. Anti-human myeloperoxidase (hMPO) antibody was detected via ELISA.


RESULTS
A 2,493-bp sequence encompassing the 2,160-bp cDNA with presumably the same number and size of exons as hMPO was generated. Translation predicted 85% homology with hMPO. Feline myeloperoxidase was localized to neutrophil primary granules, and immunoblotting revealed heavy and light bands with molecular weights similar to those of hMPO. The prevalence of anti-hMPO antibody did not differ between nonhyperthyroid and hyperthyroid cats or among hyperthyroid cats subclassified by treatment modality.


CONCLUSIONS
Moderate homology existed between feline myeloperoxidase and hMPO cDNA and protein. Although findings suggested a similar tertiary structure and function for the 2 proteins, they also suggested that inability to detect a high prevalence of anti-hMPO antibody in hyperthyroid cats may be attributable to antigenic differences between the human and feline proteins rather than a lack of autoantibody.
Pressler
Barrak M
BM
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA.
Robarge
Mark E
ME
Anderson
Kathleen I
KI
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001324:Autoantigens / Q000378:metabolism*; D001483:Base Sequence; D002371:Cat Diseases / Q000378:metabolism*; D002415:Cats; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic; D006980:Hyperthyroidism / Q000201:enzymology / Q000662:veterinary*; D008969:Molecular Sequence Data; D009195:Peroxidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011110:Polymorphism, Genetic
D000906:Antibodies; D001324:Autoantigens; D018076:DNA, Complementary; D009195:Peroxidase