Granulocyte colony-stimulating factor effects on lymphocytes and immunoglobulin concentrations in periparturient cows

Immunomodulatory effects of recombinant bovine granulocyte colony-stimulating factor were evaluated in periparturient dairy cows. Eleven of 21 cows were experimentally infected with Staphylococcus aureus in one mammary quarter prior to the study. Cows were assigned to four groups in a randomized complete block design to evaluate the effects of recombinant bovine granulocyte colony-stimulating factor (5 micrograms/kg of body weight or placebo injected subcutaneously once daily beginning 14 d prepartum through 10 d postpartum) on infected and uninfected cows during the periparturient period. Blood lymphocytes were isolated and evaluated from 5 wk before expected parturition through 7 wk postpartum. Lymphocyte function was evaluated using a blastogenesis assay, a mitochondrial methylthiazoltetrazolium cleavage activity assay, and an in vitro assay of IgM production. Serum concentrations of IgM, IgG1, conglutinin, and hemolytic complement were also determined. Injections of cows with recombinant bovine granulocyte colony-stimulating factor resulted in enhanced lymphocyte blastogenesis and mitochondrial methylthiazoltetrazolium cleavage activity in unstimulated cultures, higher serum IgM, and increased in vitro IgM production by B lymphocytes. These data provide support for the use of recombinant bovine granulocyte colony-stimulating factor to alleviate immunosuppression in periparturient cows.