Effect of Cocoa Procyanidins on the Secretion of Interleukin-4 in Peripheral Blood Mononuclear Cells

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Abstract
Given the widespread ingestion of cocoa in many cultures, we investigated whether cocoa, in its isolated procyanidin fractions (monomer through decamer), would modulate synthesis of the antiinflammatory cytokine, interleukin-4 (IL-4). Both resting and phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC) were investigated at the protein secretion level. The smaller-sized cocoa fractions (tetramer or less) were unable to induce an IL-4 response (i.e., values fell below the detection limit of 0.25 pg/ml). The larger oligomeric procyanidins (pentamer or greater) stimulated secretion of IL-4 in resting PBMC by as much as 1.42 pg/ml, as shown by the nonamer. However, only the hexameric, heptameric, and decameric fractions proved to be statistically significant. Cells coincubated with PHA showed an immense increase in secretory IL-4 (21.1 ± 1.1 pg/ml). Only the monomeric fraction was able to enhance PHA-induced secretion by 48%. The other procyanidin oligomers suppressed IL-4 production; in particular, the hexameric, heptameric, and octameric fractions significantly inhibited mitogen-stimulated secretion of IL-4, by 55%, 61%, and 71% respectively. This study offers additional data for consideration of the health benefits of dietary polyphenols from a wide variety of foods, including those benefits associated specifically with cocoa and chocolate consumption.