SUMMARY
A review of the literature on the immunology of CFS reveals that people who have Chronic Fatigue Syndrome (CFS) have two basic problems with immune function that have been documented by most research groups: 1. immune activation, as demonstrated by elevation of activated T lymphocytes, including cytotoxic T cells, as well as elevations of circulating cytokines; and 2. poor cellular function, with low natural killer cell cytotoxicity (NKCC), poor lymphocyte response to mitogens in culture, and frequent immunoglobulin deficiencies, most often IgGl and IgG3. These findings have a waxing and waning temporal pattern which is consistent with episodic immune dysfunction (with predominance of so called T-helper type 2 and proinflammatory cytokines and low NKCC and lymphoproliferation) that can be associated as cause or effect of the physiological and psychological function derangement and/or activation of latent viruses or other pathogens. The interplay of these factors can account for the perpetuation of disease with remission/exacerbation cycles. Therapeutic intervention aimed at induction of a more favorable cytokine expression pattern and immune status is discussed.