Fig 3.

B cells with memory phenotype are generated in PfMSP-1₁₉-primed mice but these are short-lived. Splenocytes and bone marrow cells recovered from three mice per time point from PfMSP-1₁₉-primed or adjuvant-treated control mice at different days postimmunization were stained with B220, CD27, and IgG1. (A and B) The contour plot shows the expression of CD27 and IgG1 on gated B220⁺ cells. The average frequency (C) and total number (D) of CD27^high IgG1⁺ cells in spleen and bone marrow cells were calculated, and results are depicted as line graphs. (E) Differentiation of memory B cells to Ag-specific ASCs in response to recall antigen in vitro. Spleen and bone marrow cells were isolated from PfMSP-1₁₉-primed mice at indicated days after the last immunization, depleted of CD138⁺ plasma cells, and cultured with PfMSP-1₁₉ for 5 days. The numbers of PfMSP-1₁₉-specific ASCs were determined by ELISPOT assay. The cells were recovered from tissues of four mice per time point, and the results are representative of three independent experiments. ***, P < 0.001 (statistically significant difference between spleen and bone marrow).