Muscle changes were accompanied by larger changes for monocyte phenotype and NK-cell characteristics, including absolute numbers, tumor cell cytotoxicity and expression of perforin and granzyme B. Together, these data suggest that HIIT-based exercise may be an important lifestyle intervention capable of improving physical and immunological functions critical to maintaining the health of older adults with treatment naïve CLL. The gene discussed is PRF1; the disease is neoplasm.