Retinoid-induced modulation of immunoglobulin M secretion by bovine mononuclear leukocytes in vitro

Influence of vitamin A supplementation in milk on growth, health, concentrations of vitamins in plasma, and immune parameters of calves

Seventy-seven Holstein calves were used to determine effects of vitamin A supplementation (0, 15,000, or 30,000 IU/d) of milk fed to calves through 6 wk of age. Effects of gender of calves and parity of dams also were considered. Supplementation with vitamin A did not affect retinol concentrations in plasma; however, calves fed milk containing supplemental vitamin A had decreased alpha-tocopherol concentrations in plasma at 6 wk compared with the concentrations in plasma of calves that were fed milk without supplemental vitamin A. Growth, serum protein, serum immunoglobulin (Ig) M and IgG, leukocyte proportions, and weekly fecal scores were not affected by vitamin A supplementation. Calves that scoured were fed milk supplemented with an additional 0 or 30,000 IU/d of vitamin A. Supplementation with an additional 30,000 IU/d when calves were scouring increased treatment days. Female calves had lower body measurements (weight, length, and height) at birth and greater fecal scores for wk 2 and 3 than did male calves. Gender did not affect serum protein, IgM, or IgG; however, female calves had higher percentages of monocytes and lower percentages of T cells than did male calves. At 6 wk, female calves also had higher percentages of B cells than did male calves. These data indicate that ratios of vitamins A and E should be considered in dietary formulations for calves. Also, additional vitamin A provided by some scour treatments could be detrimental to calves that are already receive vitamin A supplementation.

Reactivity and phenotype of mononuclear leukocytes from nongravid heifers after in vitro exposure to 9,13-di-cis-retinoic acid

The predominant isomer of retinoic acid in the plasma of dairy cows during the periparturient period is 9,13-di-cis-retinoic acid. Because retinoic acids influence the activity of cells in a variety of tissues, including the immune system, the potential for this isomer to modulate the bovine immune system during the periparturient period must be considered. The present study examined the in vitro effects of 9,13-di-cis-retinoic acid on the reactivity and phenotype of blood mononuclear leukocytes from nongravid Holstein heifers that were sensitized to antigens and that had naturally low plasma concentrations of 9,13-di-cis-retinoic acid. In this system, 9,13-di-cis-retinoic acid, approximating the highest plasma concentrations occurring in vivo during the periparturient period, had no effect on DNA synthesis, secretion of interleukin-2 or interferon-gamma, or secretion of immunoglobulin by unstimulated cultures or cultures stimulated by mitogen (pokeweed mitogen) or antigen (ovalbumin). The composition of unstimulated and stimulated mononuclear leukocyte populations, based on percentages of specific cell types, was unaffected by 9,13-di-cis-retinoic acid at the physiologic concentration of 10(-8) M. 9,13-di-cis-Retinoic acid did not affect the actual number of cells in unstimulated cultures and cultures stimulated by antigen but did cause a moderate reduction in the number of cells, primarily CD4+ lymphocytes, in cultures stimulated by mitogen. Overall, these results suggest that the elevated concentration of 9,13-di-cis-retinoic acid in maternal plasma may have a negligible effect on the reactivity and phenotype of cells constituting the circulating mononuclear leukocyte population.

Effects of replacement of native fat in colostrum and milk with coconut oil on fat-soluble vitamins in serum and immune function in calves

Fat-soluble vitamins and their metabolites modulate immune function in a variety of animal species. The objective of the present study was to determine the role of fat-soluble vitamins in colostrum and milk in the development of specific aspects of immune function in the calf during the 1st wk postpartum. During this period, control calves (n = 6) were fed normal colostrum and milk, and calves in the treatment group (n = 6) were fed skimmed colostrum and skimmed milk supplemented with coconut oil. Treated calves did not experience the progressive increase in concentrations of retinol, beta-carotene, alpha-tocopherol, 1,25-dihydroxyvitamin D, or retinoic acids in serum that was observed in control calves. Acquisition of passive immunity, which is indicated by concentrations of immunoglobulin G1 in serum, was unaffected by treatment. Composition and functional capacities of populations of blood mononuclear leukocytes that were collected from birth to 7 d postpartum were also unaffected by treatment. Major changes in the function and composition of mononuclear leukocyte populations from all calves occurred during the experimental period and were unrelated to the concentrations of fat-soluble vitamins in serum. Populations of blood mononuclear leukocytes from calves were functionally hyporesponsive and compositionally different from populations of blood mononuclear leukocytes from adult nongravid cows. These differences likely reflected the immaturity of the immune system of the neonatal calf and may contribute to the increased susceptibility of the calf to infectious disease.

Associations between function and composition of blood mononuclear leukocyte populations from Holstein bulls treated with dexamethasone

To characterize further the effects of corticosteriod-induced stress on the immune system of dairy cattle, functional and phenotypic characteristics of populations of blood mononuclear leukocytes from control and treated (0.04 mg dexamethasone/kg per d for 3 consecutive d) Holstein bulls were evaluated concurrently. In vivo administration of dexamethasone caused a > or = 97% reduction in in vitro secretion of interferon-gamma by pokeweed mitogen-stimulated mononuclear leukocytes by d 2 after the first treatment. In vitro secretion of immunoglobulin M was reduced by > 50% on d 2 and 3 after the first treatment, but returned to normal concentrations sooner than did interferon-gamma secretion. Concurrent with changes in the secretion of these proteins were changes in the mean fluorescence intensities of major histocompatibility class I and II antigens and the WC1 antigen and in the proportion of B cells, CD3 T cells, gamma delta T cells, and cells in the leukocyte population expressing major histocompatibility class II antigens. Examination of the relationships between protein secretion in vitro and the composition of the blood mononuclear leukocyte population indicated that secretion was associated positively with the proportion of CD3 T cells (primarily the gamma delta T-cell subset) and the expression of major histocompatibility class I and II molecules and associated negatively with the proportion of cells expressing major histocompatibility class II antigens. Overall, these results suggest that corticosteroid-mediated stress in dairy cattle impairs secretion of proteins that are critical to normal cellular and humoral immune responses, an effect that is strongly linked with changes in the composition of the circulating mononuclear leukocyte population.

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 three replicate experiments evaluating the effects of 13-cis-retinoic acid 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 treatments. Parameters measured were IgM production in vitro by blood lymphocytes, serum Ig concentrations, and the phenotype of peripheral blood mononuclear leukocytes. Administration of 13-cis-retinoic acid had no effect on in vitro Ig production induced by pokeweed mitogen; however, supplementation of the same cultures with 13-cis-retinoic acid enhanced production of polyclonal IgM. Serum Ig concentrations and total numbers of peripheral blood leukocytes and numbers within mononuclear leukocyte 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 function in vivo.

Administration of 13-cis-retinoic acid to dairy cattle. 1. Plasma retinoid concentrations and lymphocyte blastogenesis

Effects of administration of 13-cis-retinoic acid on concentrations in plasma of retinoic acid isomers, retinol, and beta-carotene and on in vitro mitogen-stimulated lymphocyte blastogenesis of peripheral blood mononuclear leukocytes were evaluated in Holstein cattle. Treatments consisted of i.m. injections of 0 (vehicle only), 100, 200, or 400 mg of 13-cis-retinoic acid in dimethylsulfoxide for 7 d. Concentrations of 13-cis- and all-trans-retinoic acids in plasma and in mononuclear leukocytes were elevated in a dose-dependent manner by administration of 13-cis-retinoic acid. Treatment with 13-cis-retinoic acid, however, had no effect on concentrations of retinol and beta-carotene in plasma. In vitro DNA synthesis in unstimulated and mitogen-stimulated mononuclear leukocyte cultures was unaffected by in vivo administration of 13-cis-retinoic acid. In contrast, in vitro supplementation of unstimulated and mitogen-stimulated mononuclear leukocyte cultures with 13-cis-retinoic acid inhibited DNA synthesis relative to unsupplemented cultures. In conclusion, elevated plasma and intracellular concentrations of 13-cis- and all-trans-retinoic acids produced by repeated i.m. administrations of 13-cis-retinoic acid did not affect peripheral blood mononuclear leukocyte function, as measured by the in vitro blastogenic response of peripheral blood lymphocytes.