We agree with Drs Hamer and Meydani that characterizing clinical immune responses in our ever-expanding advanced elderly population is of interest and importance. A number of the points that they raise were addressed in the "Comment" section of our article. Among the many parameters of immune function that can and have been tested in the elderly, we focused on B-cell function to characterize the ability of healthy older patients to produce antibodies in response to immunization. Our in vivo tests, such as determination of total immunoglobulin levels and antibody responses to vaccines, and of in vitro tests, such as measurement of responses to pokeweed mitogen (T-cell and T-cell– dependent B-cell responses) and Staphylococcus aureus Cowan strain 1 (a more T-cell–independent B-cell stimulus) reflects this focus. Because the literature suggests that both IL-2 production and responses to IL-2 may be impaired with aging, we compared B-cell responses to S aureus Cowan strain 1 with and without the exogenous T-cell–derived IL-2 to determine whether this cytokine would reverse any potential age-associated defects.
Carson P, Nichol KL, Janoff EN. Immune Function in the Elderly—Reply. Arch Intern Med. 2001;161(3):482-483. doi: