High levels of apoptosis in lymphocytes of individuals living in a malaria-endemic area : abstract

The levels of spontaneous apoptosis of lymphocytes from four groups of healthy individuals have been evaluated in 3-day-old in-vitro cultures. The cell nuclei were stained with propidium iodide and the fluorescence quantified with a cytofluorometer. Under comparable culture conditions, the percentages of apoptotic nuclei were found to be significantly higher in lymphocytes from subjects living in an area holoendemic for malaria, with a high rate of parasite transmission, than in lymphocytes from subjects living in area where transmission is at a low level and seasonal. The plasma concentration of soluble interleukin-2 receptor was also found to be higher in subjects from endemic areas than in other groups, indicating different levels of lymphocyte activation. The high level of spontaneous apoptosis found in some batches of lymphocytes in vitro Fould be associated with this cell activation. All other factors being comparable between the different groups of individuals, the most probable origin of such activation would be malarial infection. It is conceivable that the withdrawal of the lymphocytes from their natural environment to one apparently devoid of cytokines could also iliduce their death by apoptosis.