Studies by James McKay found that people who are open and friendly to strangers had half the rate of major illnesses of those who kept a cold and distant attitude toward strangers. These “affiliator types” (people who value relationships) had stronger defenses against viruses and cancer cells and their CD-4/CD8 ratios were better. CD stands for “clusters of differentiation,” and the immune cells that have the CD8 marker on the membrane kill invaders such as viruses. The cells with CD4 markers on their membranes are necessary to help the CD8s work. For that reason, CD4s are known as T-helper cells.
McKay J. Assessing aspects of object relations associated with immune function: Development of the Affiliative Trust-Mistrust coding system. Psychological Assessment, 1991;3(4):641-647.
Social support at its best includes mutual feelings of love, as the experience of love is physiologically regenerative. There is an expression: Love heals all. And it has been shown that people in loving relationships are healthier than people in contentious ones.
Well-known Harvard University Health Service physician and researcher Dr. David McClelland tested immune function on students who were shown films that triggered loving feelings. He found that the films resulted in increased NK cells, increased IgA, and overall improvements in immune cell numbers as well as function
McClelland D. Some reflections on the two psychologies of love. J of Personality, 1986;54:334-353.
McClelland D, and Kirshnit C. The effect of motivational arousal through films on salivary immunoglobulin A. Psychology and Health, 1988;2:31-52.