In the present pilot investigation, the susceptibility of T-lymphocytes from Alzheimer's disease (AD) subjects (n=22) and aged-matched, non-demented controls (CNT) (n=12) was examined with ultraviolet (UV) B light-induced apoptosis in vitro. The basal apoptotic ratios were similar in both groups. However, the AD lymphocytes displayed significantly (p<0.0001) lower apoptotic levels than those of the CNT lymphocytes at all of the applied UVB exposure doses (100, 200 and 300 mJ/cm(2)). These observations indicate that AD lymphocytes are more resistant than CNT lymphocytes to UVB irradiation.