Formerly Grifron-Pro Dietary Supplement. Ultimate Immune Enhancer. Maitake has been prized in traditional Japanese herbology for hundreds of years. Modern science has identified in Maitake. Proteoglucan ,. Beta-1,3 glucan and. Beta-1,6 glucans combined with protein, as an active constituent to support the immune system.*. Maitake D-fraction is a standardized from of pure and active.