Interferon and 2′,5′-oligo(A) synthetase activities in serum and blood mononuclear leukocytes of cattle after injection of bovine interferon-α1

Louis J. Perino From the Departments of Veterinary Parasitology, Microbiology, and Public Health (Perino, Burge, Winter, Fulton) and Physiological Sciences (Short), College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078.

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Everett C. Short Jr. From the Departments of Veterinary Parasitology, Microbiology, and Public Health (Perino, Burge, Winter, Fulton) and Physiological Sciences (Short), College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078.

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Lurinda J. Burge From the Departments of Veterinary Parasitology, Microbiology, and Public Health (Perino, Burge, Winter, Fulton) and Physiological Sciences (Short), College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078.

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Douglas A. Winter From the Departments of Veterinary Parasitology, Microbiology, and Public Health (Perino, Burge, Winter, Fulton) and Physiological Sciences (Short), College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078.

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Robert W. Fulton From the Departments of Veterinary Parasitology, Microbiology, and Public Health (Perino, Burge, Winter, Fulton) and Physiological Sciences (Short), College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078.

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Summary

Cell extracts that were prepared from blood mononuclear leukocytes from 66 samples obtained from 6 clinically normal calves contained mean 2′,5′-oligoadenylate (2′,5′-oligo[A]) synthetase activity sufficient to synthesize 186 ± 82 pmol of 2′,5′-oligo(A)/h/106 cells. Calves had no measurable serum interferon (ifn) activity. Five calves were given im injections of 104, 105, 5 × 105, 106, and 107 U of bovine ifn-α1/kg of body weight at 2-week intervals. Five dosing sequences were used with a 5 × 5 Latin square design so that each calf received each dose once. Activity of 2′,5′-oligo(A) synthetase increased at 24 hours in response to all dosages of ifn and then declined following first-order kinetics, with an apparent half-life (t½) of 2.1 ± 0.5 days. The area under the concentration-time curve for 2′,5′-oligo(A) synthetase increased with dose of ifn more rapidly than did peak response. Serum ifn that was measured at 1-day intervals following administration of ifn was consistently measurable only at dosages above 106 U of ifn/kg. The t½ for circulating ifn was 12.4 ± 1.0 hours. Over all dosages, increases in 2′,5′-oligo(A) synthetase activity were measurable for 3.5 days longer than were increases in ifn following im injection of ifn. None of the calves developed detectable anti-ifn antibodies.

Summary

Cell extracts that were prepared from blood mononuclear leukocytes from 66 samples obtained from 6 clinically normal calves contained mean 2′,5′-oligoadenylate (2′,5′-oligo[A]) synthetase activity sufficient to synthesize 186 ± 82 pmol of 2′,5′-oligo(A)/h/106 cells. Calves had no measurable serum interferon (ifn) activity. Five calves were given im injections of 104, 105, 5 × 105, 106, and 107 U of bovine ifn-α1/kg of body weight at 2-week intervals. Five dosing sequences were used with a 5 × 5 Latin square design so that each calf received each dose once. Activity of 2′,5′-oligo(A) synthetase increased at 24 hours in response to all dosages of ifn and then declined following first-order kinetics, with an apparent half-life (t½) of 2.1 ± 0.5 days. The area under the concentration-time curve for 2′,5′-oligo(A) synthetase increased with dose of ifn more rapidly than did peak response. Serum ifn that was measured at 1-day intervals following administration of ifn was consistently measurable only at dosages above 106 U of ifn/kg. The t½ for circulating ifn was 12.4 ± 1.0 hours. Over all dosages, increases in 2′,5′-oligo(A) synthetase activity were measurable for 3.5 days longer than were increases in ifn following im injection of ifn. None of the calves developed detectable anti-ifn antibodies.

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