Fig. 2: Mouse and human B cells synthesize and secrete GABA.

a, MS analysis of glutamine, glutamate and GABA in purified CD4⁺ T cells, CD8⁺ T cells, CD11b⁺ and/or CD11c⁺ macrophages and dendritic cells (Mf/DC) or B220⁺ B cells from the cLNs and iLNs of immunized WT mice as in Fig. 1a (n = 3; ND, not done). b, MS-determined GABA levels in B cells from LN (n = 10), spleen (SPL; n = 4), bone marrow (BM; n = 3), Peyer’s patches (PP; n = 4) and small intestinal lamina propria IgA⁺ plasma cells (SILP IgA⁺ PC; n = 4), relative to naive CD4⁺ T cells from the LN of non-immunized WT mice (n = 13). c, B cells (± anti-IgM and anti-CD40) and T cells (± anti-CD3, anti-CD28 and IL-2) were cultured with ¹³C₅,¹⁵N₂-labelled glutamine for 24 h (n = 2) or 72 h (n = 4). Isotope-labelled glutamate and GABA were measured by MS in cell lysate or supernatant. d, GABA measured by MS in B cells or supernatant after 72 h of treatment with anti-IgM and anti-CD40 (n = 8), anti-IgM (n = 7) or LPS (n = 7), relative to non-stimulated cells (n = 6) or as absolute concentration (n = 5). e, f, Human tonsil B cells were stimulated with a mix of anti-IgM and anti-IgG (BCR), CpG (TLR9 agonists), IFNα and IL-2 (n = 4) or a mix of IL-21, CD40L and IL-2 (n = 3) for 5 d with ¹³C₅,¹⁵N₂-labelled glutamine. The percentage of isotope-labelled and unlabelled GABA in cells (e) and the level of isotope-labelled GABA in cells and supernatant relative to that in non-stimulated cells (f), as measured by MS, are presented (n = 3). Significance was calculated by unpaired two-tailed t-test (a, b, f), one-way ANOVA (d) or two-way ANOVA (e): *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001; NS, not significant;. Data are shown as mean ± s.e.m. (a–d, f) or –s.e.m. (e). n indicates the number of biological (a–c) or technical (d–f) replicates. Data are pooled from two (d, left) or three (b) experiments. Exact P values are provided in the Source Data.

Source data