Reduction of Ca2+-transporting systems in memory T cells

Antigen-specific B and T memory lymphocytes are the basis of immunological memory. Their major functional difference from naive cells is a rapid and a mplified response to an antigen-pathogen. Besides, a substantial difference memory and naive T cells is different sensitivities of these two T lymphoc yte subpopulations to Ca2+ ionophores. We carried out comparative analysis of Ca2+ signals of immune memory cells and naive T lymphocytes of CBA/J mice in response to addition of Ca2+-mobil izing agents (concanavalin A, thapsigargin, and ionomycin), The effective c oncentrations of the listed agents differed highly in naive and memory T ce lls. Hence, the depletion of intracellular Ca2+ stores didn't activate Ca2 entry. The treatment of the studied cells with ionomycin and thapsigargin in a Ca2+-free medium revealed the absence of intracellular Ca2+ pools in m emory T cells, which may account for their stability to ionophores. Using S H-reagent thimerosal, the reduction of the Ca2+ influx system in memory T c ells under the action of Ca2+-mobilizing agents was shown. It was also found that memory T cells are resistant to the "Ca2+-paradox". The addition of 2 mM CaCl2 to the cells previously incubated with 0,5 mM EG TA in the presence or absence of the Ca2+-mobilizing agents did not induce Ca2+ influx into the cells.