| Blue-green algae, historically consumed as a food source in certain native cultures, has more recently been promoted as a nutritional supplement for the general public. Several claims have been made regarding the consumption of blue-green algae. Such claims range from increased physical and mental energy to the treatment of neurological disorders and the enhancement of the immune system.; In order to determine whether the species of blue-green algae Aphanizomenon flos-aqua (AFA) has effects on immune cell circulation and function, 21 volunteers were involved in a crossover, double-blinded placebo-controlled study. Results reveal that two hours after AFA consumption, there was a generalized mobilization of lymphocytes and monocytes. This mobilization included increases in the CD3+, CD4+, and CD8+ T cell subsets, and of CD19+ B cells, in peripheral blood. In neither the CD4+ nor the CD8+ subsets however, were changes observed in the relative proportions of naive versus memory T cells. In addition, the relative proportions and absolute numbers of natural killer (NK) cells in peripheral blood were reduced after AFA consumption. This effect did not occur with polymorphonuclear (PMN) cells.; Using in vitro techniques to elucidate possible mechanisms of these in vivo observations, we have found that AFA binds to the L-selectin molecule on lymphocytes and PMNs. Furthermore, it does not directly activate lymphocytes, as evaluated by tyrosine phosphorylation, and by proliferative activity. Similarly, AFA does not induce reactive oxygen species formation in PMNs in vitro, and appears to slightly reduce the phagocytic activity of PMNs harvested from volunteers 2 hours post-consumption (ex-vivo).; Further studies are required to determine the components of AFA that are responsible for these phenomena. By altering the circulation of specific leukocyte subsets however, AFA represents a novel approach to modulating immune surveillance. Such an approach may have implications in the treatment and prevention of infection, cancer, and immunodeficiency states. |
