Immunomodulatory drugs are available to maintain immune homeostasis but some have undesirable side effects. Six oligo- and poly-saccharides were assessed for their pro- and anti-inflammatory responses in two in vitro model systems, the monocytic THP-1 cell line and human whole blood cultures (HWBC). The compounds were first characterised for their molecular mass and physical properties. Following incubation with lipopolysaccharide (LPS) or the compounds, cytokine and chemokine secretion was assayed in both models and intracellular TNF-α was measured by flow cytometry in HWBC cell sub-populations. LPS, inulin, galacturonan, heteroglycan and fucoidan demonstrated pro-inflammatory properties and intracellular TNF-α expression was increased in the monocytes of HWBC. Mannan and xyloglucan did not elicit any significant responses. Inulin induced maximum cytokine secretion and heteroglycan induced maximum chemokine secretion in HWBC. This study emphasises the potential of inulin and heteroglycan as potential immunomodulatory therapeutics and that HWBC had a greater and more varied response in comparison to THP-1 cells.