Abstract: Aim In this study, we investigated the changes of lymphocyte subpopulation and apoptosis process of lymphocytes in the elderly, and the modulatory effect of pollen extract (PE) on apoptosis. Methods Lymphocyte phenotypes were detected using indirect immunofluorescence technique. The proliferation responses were determined by MTT method. Flow cytometry and automatic image analysis were performed to evaluate the apoptosis of lymphocytes. Results The proliferation responses of lymphocytes in the elderly were lower than that in young adults. Decreased CD45 RA+ cells and increased CD45 RA+ cells were found in lymphocyte population of aged people, compared with that of young adults. The CD45 RA+ cells were prone to apoptosis. There is an inhibitory effect of PE on apoptosis of lymphocytes in the elderly. Conclusion It is implied that the susceptibility of lymphocyte in the elderly to apoptosis depends on activation, so called, activation-induced cell death. Present results suggest that apoptosis of lymphocytes in aged people play an important role in the pathogenesis of immunosenescence. Thus, a possibility is open for development of apoptosis-modulating drugs from pollen.

Key words: pollen extract, pollen extract, lymphocytes, lymphocytes, apoptosis, apoptosis, CD45 RA+ cells, CD45 RA+ cells, automatic image analysis, automatic image analysis