NK-3 Immune® Supports Natural Killer Cell Activity NK-3 Immune® with selenium supports numerous natural immune processes, activating the work of macrophages, T cells, B cells, and natural killer or NK cells, the body’s “first line of defense.” It stimulates the production of the chemical messengers that activate the body’s natural immune response and it also supports a healthy circulatory system.RBAC™ is a trademark of Daiwa Pharmaceutical Co., Ltd., Japan.* 250 mg Capsule Option Available: 30, 60 Suggested Use: 4 capsules three times per day for the first 4 weeks. After 4 weeks, reduce dosage to the maintenance level of 4 capsules daily.