Inductions of memory-like B cells and plasma-like cells from human naïve B cells in hypoxic cultures

Recently, we induced memory-like T cells from human naïve T cells in a hypoxic culture. In this study, we attempted induction of both memory B cells and plasma cells from human naïve B cells in hypoxic cultures. Although the hypoxic culture (1% O2) did not support the survival of naïve B cells, it supported the survival of B cells that were activated by interleukin 4 (IL-4) and lipopolysaccharides (LPS). On activation culture Day 7, there was no survivor in 20% O2, but 29.5% of the activated B cells survived in 1% O2. Next, we withdrew both IL-4 and LPS from the B-cell culture preactivated for 7 days in 1% O2, and the culture was continued for another 7 days. As a result, 12.4% of the B cells survived. These memory-like B cells decreased in body size and number of cytoplasmic granules. Moreover, we tried to induce plasma-like cells. Human naïve B cells were activated by two-step culture for 9 days, after which all activators were withdrawn from the medium, and the cells were cultured for an additional 6 days in 1% O2. The viability was 0.2%, but over 92% of the survivors showed a CD20-/CD27+/CD38+ plasma cell phenotype.