Extraction of polysaccharides from maca: Characterization and immunoregulatory effects on CD4⁺ T cells

The immunomodulatory effects of maca polysaccharides (MCPs) on macrophages have been demonstrated in many studies. However, the effects of MCPs on CD4⁺ T cells have not been studied. Four water-soluble MCPs, labeled MCP1 (weight-average molecular weights [Mws] of 896.1 and 276.6 kDa), MCP2 (Mws of 337.8 and 219.0 kDa), MCP3 (Mws of 110.6, 58.1, and 38.9 kDa), and MCP4 (Mws of 15.7, 12.6, and 12.1 kDa), were obtained from maca by graded ethanol precipitation. The immunoregulatory effects of MCPs on CD4⁺ T cells were evaluated for the first time. The experimental results indicated that all MCPs had immunoregulatory effects on CD4⁺ T cells. However, the effects of MCP2 were stronger compared to the other three components, not only in promoting the proliferation of CD4⁺ T cells but also in terms of secretion of interferon-γ (IFN-γ). The molecular weight and monosaccharide compositions of MCPs were analyzed to explore the structure-activity relationship. The results suggested that the molecular weight and the galactosamine (GalN) of MCPs might be determining factors for its bioactivity. These findings suggest that the MCP2 isolated in our study have immune potentiation effects on CD4⁺ T cells.