Long-lived B cells: mitogen reactivity as a tool for studying their life-spans

A population of noncycling small lymphocytes has been selectively enriched in mice by treatment with hydroxyurea (HU) over 4 consecutive days. This cell population, present in the spleen of HU-treated mice, contained a high frequency of lipopolysaccharide (LPS)-reactive cells and this could be used as a functional marker to follow their persistence after transfer to LPS-nonresponder recipient mice. The results reported here show that cells selected after a long-term HU treatment have considerably less decay, after transfer in recipient mice, than normal spleen cells. Furthermore, they demonstrate that HU-selected B cells survive in the recipient mice for periods up to 3 months, and are, consequently, true long-lived lymphocytes.