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Retinoid-induced modulation of immunoglobulin M secretion by bovine mononuclear leukocytes in vitro
B J Nonnecke1, T A Reinhardt, S T Franklin
1USDA, Agricultural Research Service, National Animal Disease Center, Ames, IA 50010-0070.
Insights
Retinoids like retinol and retinoic acid influence IgM secretion in bovine immune cells. Specific isomers and concentrations differentially affect pokeweed mitogen-stimulated leukocytes, highlighting their immunomodulatory roles.
Area of Science:
- Immunology
- Biochemistry
- Cell Biology
Background:
- Retinoids, including retinol and retinoic acid, are crucial for immune function.
- Understanding their specific effects on B-cell antibody production is important for immunology.
Purpose of the Study:
- To investigate the in vitro effects of trans and cis isomers of retinol and retinoic acid on immunoglobulin M (IgM) secretion.
- To determine how different concentrations of these retinoids impact bovine peripheral blood mononuclear leukocytes.
Main Methods:
- Bovine peripheral blood mononuclear leukocytes were cultured and stimulated with pokeweed mitogen.
- Cultures were supplemented with various concentrations (10⁻¹⁰ to 10⁻⁶ M) of retinol and retinoic acid isomers.
- Polyclonal IgM concentrations in culture supernatants were quantified using an enzyme-linked immunosorbent assay (ELISA) after 14 days.
Main Results:
- Pokeweed mitogen stimulation significantly increased IgM secretion compared to unstimulated cultures.
- Retinoid supplementation did not alter basal IgM secretion in unstimulated cells.
- All-trans-retinoic acid enhanced IgM secretion at low concentrations (10⁻¹⁰ M) and inhibited it at high concentrations (10⁻⁶ M).
- Other retinoids enhanced IgM secretion at certain concentrations, with retinoic acid isomers showing effects at lower concentrations than retinol isomers.
Conclusions:
- Retinol and retinoic acid isomers modulate polyclonal IgM secretion by mitogen-stimulated bovine mononuclear leukocytes.
- The effects are concentration-dependent and isomer-specific.
- Further research is needed to identify affected leukocyte subsets and the role of trans-retinoic acid as a metabolite.
Abstract:
Effects of trans and cis isomers of retinol and retinoic acid on IgM secretion by bovine peripheral blood mononuclear leukocytes were evaluated in vitro. Mononuclear leukocyte cultures that were unstimulated or stimulated by pokeweed mitogen were supplemented with isomers of retinol and retinoic acid at 10(-10) to 10(-6) M. Concentrations of polyclonal IgM in supernatants from 14-d cultures were measured by an ELISA. Cultures stimulated by pokeweed mitogen consistently secreted more IgM than parallel, unstimulated cultures. Retinoid supplementation did not affect basal IgM secretion by unstimulated cultures. However, each retinoid affected IgM secretion by cultures stimulated by mitogen. The nature of the effect was dependent on the concentration of the specific retinoid. All-trans-retinoic acid enhanced secretion at 10(-10) M and inhibited secretion at 10(-6) M. The other retinoids, however, did not inhibit IgM secretion at any concentration. Each retinoid enhanced IgM secretion at one or more concentrations, although enhancement was produced by much lower concentrations of retinoic acid isomers than retinol isomers. These results indicate that retinol and retinoic acid modulate polyclonal IgM secretion by cultures of bovine mononuclear leukocytes stimulated by mitogen. Future research will determine which subsets of the mononuclear leukocyte population are affected and whether trans-retinoic acid is the metabolite that produces these effects.
