ANALYSIS OF THE HAIRLESS MOUSE AS A MODEL FOR THE EFFECTS OF AGING ONTHE IMMUNE-SYSTEM

Studies into the effects of aging on the immune system are hampered by the lack of a suitable animal model that is readily available and cos t efficient. The mutant mouse, hairless (hr/hr genotype), has been sho wn to undergo an accelerated thymic involution with accompanying immun odeficiency. Thus, this strain of mouse has been proposed as a model f or studying the interactions of aging and immune function. We have inv estigated the effects of homozygous hr gene expression over time on th e immune function of these mice. It was observed that homozygous hr ge ne expression had minimal effects on peripheral lymphocyte subset comp ositions but did appear to result in changes in thymic differentiation . Further, hr/hr mice displayed decreased proliferative responses to I L2 and mitogen stimulation, although cytotoxic responses (both NK and T cell mediated) appeared normal. These defects appear to be attributa ble to T helper cell dysfunction. Each of the changes found in hr/hr m ice were distinct from those seen with age-matched control mice. Thus, the hr/hr inbred strain of mouse does not appear to be a suitable mod el for use in analyzing the effects of aging on the immune system.