Potentiation of Antibiotic Therapy for Bovine Mastitis by Recombinant Bovine Interleukin-2

¹ Immunology Group, Agricultural Research Division, American Cyanamid Co., PO Box 400, Princeton, NJ 08543-0400

Adjunct therapy with recombinant bovine interleukin-2 and antibiotics for Staphylococcus aureus IMI was investigated in an attempt to improve the therapy of antibiotics alone. Treatment of established S. aureus IMI with Na-cephapirin or Cefa-Lak® produced average cures of 32.0 and 41.8%, respectively. When Na-cephapirin treatment was combined with recombinant bovine interleukin-2 at either 3.3 or 10 mg, the therapeutic efficacy was improved by an average of 20 to 30%. When Cefa-Lak® treatment was combined with recombinant bovine interleukin-2 at 10 mg, the therapeutic efficacy was improved on average by 20%. Recombinant bovine interleukin-2, formulated in the excipient of the commercial Cefa-Lak®, also improved the therapeutic efficacy by 16% compared with Cefa-Lak® alone. Recombinant bovine interleukin-2, formulated in Cefa-Lak®, maintained biological activity at room temperature for at least 21 d. After intramammary infusion of recombinant bovine interleukin-2, no biologically active interleukin-2 was detected in milk 48 h (four milkings) after administration. These data suggest that cytokines may be used as adjunct therapy with existing mastitis antibiotics or formulations of existing commercial products to improve the therapeutic efficacy.

Key Words: cytokines • mastitis • antibiotics

Submitted on March 20, 1992
Accepted on July 24, 1992