Alteration of cell cycle kinetics by reducing agents in human peripheral blood lymphocytes from adult and senescent donors

For improving cell proliferation reducing agents are routinely used as medium supplements in murine cell cultures, however, they are rarely used for human peripheral blood lymphocytes (PBLs). Data on changes in cell kinetics induced by reducing agents are not available. Here cell kinetic alterations induced by reducing agents in human lymphocytes are revealed by applying flow cytometric BrdUrd/Hoechst cell cycle analysis and by using the exit kinetic model of Smith and Martin. Applying alpha-thioglycerol (a-TG) as a model compound it was shown that the major cell kinetic effect is a shortening of the mean duration of the G0/G1 phase. The minimum G0/G1 phase duration and the percentage of the non-cycling G0/G1 cell fraction decrease only slightly. Moreover, a lower number of PBL's are arrested in the G2/M phase of the 1st cell cycle. The durations of the S and G2/M phase in the 1st and G1 phase in the 2nd cycle are not affected. These cell kinetic effects are identical for lymphocytes from both adult and senescent donors. The supplementation of the cell cultures with recombinant IL-2 did not induce similar cell kinetic alterations compared with a-TG. This indicates that the variation of the cell cycle progression factor IL-2 is not solely responsible for improvement of the cell activation process in the G0/G1 phase.