ADMINISTRATION OF 13-CIS-RETINOIC ACID TO DAIRY-CATTLE .2. PHENOTYPE OF BLOOD LEUKOCYTES AND PRODUCTION OF IMMUNOGLOBULIN

Eight Holstein dairy cattle were assigned randomly to treatments in th ree replicate experiments evaluating the effects of 13-cis-retinoic ac id on mononuclear leukocyte function. Treatments were i.m. injections of 0 (vehicle only), 100, 200, or 400 mg/d of 13-cis-retinoic acid in dimethylsulfoxide for 7 consecutive d. Peripheral blood was collected before treatment and periodically for 18 d after initiation of treatme nts. Parameters measured were IgM production in vitro by blood lymphoc ytes, serum Ig concentrations, and the phenotype of peripheral blood m ononuclear leukocytes. Administration of 13-cis-retinoic acid had no e ffect on in vitro Ig production induced by poke-weed mitogen; however, supplementation of the same cultures with 13-cis-retinoic acid enhanc ed production of polyclonal IgM. Serum Ig concentrations and total num bers of peripheral blood leukocytes and numbers within mononuclear leu kocyte subsets were unaffected by treatment with 13-cis-retinoic acid. Experimentally induced elevations in the concentrations of serum and intracellular retinoic acids did not affect mononuclear leukocyte func tion in vivo.