Figure 3

CD57⁺ GC-Th cells are more efficient than other tonsil CD4⁺ T cell subsets in helping B cells. (A) CD4⁺ T cell subsets were cultured with total tonsil CD19⁺ B cells for 7 days in the presence of SEB. Naïve B cells (C) or GC-B cells (D) were cultured with equal numbers of CD57⁺GC-Th cells or other T cell subsets (CD57^-, CD57^-CD69⁺ and CD57^-CD69^- T cells) for 7 days followed by ELISA for IgM, IgG, IgA and IgE. Data from 5 independent experiments were combined and the averages are shown with standard errors. Relative production levels to CD57⁺ GC-Th cells are shown. *Significant differences from CD57⁺ GC-Th cells. The absolute Ig production levels (ng/ml) in panel A (GC-Th + Total B cells) were 5737 ± 1764 (IgM), 2111 ± 1185 (IgG), 577 ± 186 (IgA), and 4.8 ± 2.1 (IgE). The absolute Ig production levels (ng/ml) in panel B (GC-Th cells + naïve B cells) were 2045 ± 697 (IgM), 63 ± 21 (IgG), 40 ± 23 (IgA), and 2.9 ± 1.2 (IgE). The average levels (ng/ml) of Ig produced in the cultures of GC-Th cells and GC B cells were 750 ± 279 (IgM), 175 ± 52 (IgG), 51 ± 13 (IgA), and 1.0 ± 0.5 (IgE). (D) Isotype composition of the Ig induced by CD57⁺ GC-Th cells. Naïve B cells or GC-B cells were cultured with equal numbers of CD57⁺GC-Th cells or CD57^-CD69⁺ T cells for 7 days followed by ELISA for IgM, IgG, IgA and IgE. Data from 4 independent experiments were combined and the averages are shown with standard errors. *Significant differences between naïve and GC-B cells, but not between the two T cell subsets, were observed.