Consumption of Aphanizomenon flos-aquae Has Rapid Effects on the Circulation and Function of Immune Cells in Humans A novel approach to nutritional mobilization of the immune system

Objective: To examine the short-term effects of consumption of a moderate amount (1.5 grams) of the bluegreen algae Aphanizomenon flos-aquae (AFA), on the immune system. Methods: Using a crossover, placebo-controlled, randomized, double-blind design, 21 volunteers were studied, including 5 long-term AFA consumers. Results: Consumption of a moderate amount (1.5 grams) of the blue-green algae Aphanizomenon flos-aquae results in rapid changes in immune cell trafficking. Two hours after AFA consumption, a generalized mobilization of lymphocytes and monocytes, but not polymorph nucleated cells, was observed. This included increases in CD3+, CD4+, and CD8+ T cell subsets and CD19+ B cells. In addition, the relative proportions and absolute numbers of natural killer (NK) cells were reduced after AFA consumption. No changes were observed in the relative proportions of naive versus memory T cells, neither in the CD4 nor the CD8 fractions. A mild but significant reduction in phagocytic activity was observed for polymorph nucleated cells. When freshly purified lymphocytes were exposed to AFA extract in vitro, direct activation was not induced, as evaluated by tyrosine phosphorylation and proliferative activity. Discussion: The changes in immune cell trafficking displayed a high degree of cell specificity. Long-term consumers responded stronger with respect to altered immune cell trafficking. In vitro, AFA did not induce a direct activation of lymphocytes. These data support a signaling pathway from gut to CNS to lymphoid tissue. The signals from CNS may be crucial for the rapid changes in the general distribution and specific recruitment we observed. Moderate anti-inflammatory modulation may account for the modification of phagocytic activity. Conclusion: Consumption of AFA leads to rapid changes in immune cell trafficking, but not direct activation of lymphocytes. Thus, AFA increases the immune surveillance without directly stimulating the immune system.