A new and useful method is provided, for enhancing the immune system of a donor/recipient. Stem cells are collected from the donor/recipient at a time that the donor/recipient appears to have a healthy immune system, taking into consideration the age of the donor/recipient and the characteristics of a healthy immune system for a donor/recipient of that age. The stem cells are processed and stored in a condition that enables the stem cells to be later administered to that donor/recipient in predetermined amounts, in serial (consecutive) fashion, over predetermined time intervals, and at the later request of the donor/recipient, the stem cells are administered to the donor/recipient in serial (consecutive) fashion, over predetermined time intervals, to enhance the donor/recipient's immune system thereby preventing formation of age related diseases that are caused by rundown immune system. The practice of the present invention results in replenishing the hematopoietic system and primarily rebuilding the immune system in an aged individual. Also noteworthy, it refreshes the repertoire of stem cells, which are at the point of exhaustion, bringing about extension of life span and can also be used for improvement of cognitive functions of the donor/recipient.
