![AB cells support B lymphopoiesis. (A) The percentages of eYFP+ cells within the A, AB, B, and DN populations in each Cre reporter. Data are mean ± SD (n = 3 mice per reporter, from 3 individual experiments). (B) Shown are the proportions of A, AB, B, and DN populations in calvaria, long bones, and vertebrae (n = 7 mice). (C) Heatmap showing microarray expression of B-lymphocyte regulatory factors in A, AB, B, and DN cells (n = 4 independent experiments of cells pooled from 4 mice). (D-I) Gene expression qPCR validation for Flt3l (D), Cxcl12 (E), Kitl (membrane bound [m]) (F), Kitl (secreted [s]) (G), Il7 (H), and Tnfsf11 (I) (n = 7 independent experiments of cells pooled from 3 to 4 mice). All data are mean ± SD. (J) Schematic showing coculture of pro-B lymphocytes with A, AB, B, or DN cells for 7 days, which were then assessed for the proportions of B-lymphocyte populations by FACS or transferred onto OP9 cells for an additional 7 days. (K) The proportions of pro-B, pre-B, and IgM+ B lymphocytes after 7 days of coculturing pro-B lymphocytes with A (n = 7), AB (n = 15), B (n = 9), or DN (n = 15) cells. (L) The proportions of pro-B, pre-B, and IgM+ B lymphocytes after coculturing pro-B lymphocytes with A, AB, B, or DN cells for 7 days, followed by 7 days coculture with OP9 cells. Data are shown only for cultures that produced B lymphocytes: A (n = 4), AB (n = 8), B (n = 6), or DN (n = 4). (M) The proportions of wells containing B lymphocytes after 7 days coculture with A, AB, B, and DN cells, and then 7 days after transfer onto OP9 cells. (N) Schematic showing coculture of pre-B lymphocytes with A, AB, B, or DN cells for 7 days, which were then analyzed for the proportions of B-lymphocyte populations. (O-P) The numbers of viable pre-B lymphocytes (O) and IgM+ B lymphocytes (P) after 7 days of coculture with pre-B lymphocytes with A (n = 5), AB (n = 9), B (n = 12), or DN (n = 16) cells. One-way ANOVA with Tukey’s multiple comparisons test: *P < .05; **P < .01; ***P < .001; ****P < .0001. C, calvaria; L, long bones; V, vertebrae.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/138/4/10.1182_blood.2020005865/4/bloodbld2020005865f7.png?Expires=1735524830&Signature=ttcN8jwAxLPSx5VZFYcHHe8S8~Fc6~ADuHRayWdqG7FauLW7qjs9tPu~w27gU208X6klINNLfpJZ~nh9raSSRgi7i72AgF0YF0p6HUh5p-f88Dksx7vUkHmbFuEwSv91y1QW3s2j~9VZqUb2BP-q7srq2sERWgLoALd37ZHk0s9mEILdAsaYpwu1i8wNwLa-qD7c2VPknPCdDaWt8gbt~5VJxqcaFDcvLEqIHpeC5jNanMAHY4EvAifvTGDGNHE0jTUnbn7dYo77AowwbDfAZ6ys-p3~5WoYL-sCR6Ho8WvtaxNVSlsCADj0Njx0zA~uRGM0pTvTVSBj3Vh4i2r6eg__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
AB cells support B lymphopoiesis. (A) The percentages of eYFP+ cells within the A, AB, B, and DN populations in each Cre reporter. Data are mean ± SD (n = 3 mice per reporter, from 3 individual experiments). (B) Shown are the proportions of A, AB, B, and DN populations in calvaria, long bones, and vertebrae (n = 7 mice). (C) Heatmap showing microarray expression of B-lymphocyte regulatory factors in A, AB, B, and DN cells (n = 4 independent experiments of cells pooled from 4 mice). (D-I) Gene expression qPCR validation for Flt3l (D), Cxcl12 (E), Kitl (membrane bound [m]) (F), Kitl (secreted [s]) (G), Il7 (H), and Tnfsf11 (I) (n = 7 independent experiments of cells pooled from 3 to 4 mice). All data are mean ± SD. (J) Schematic showing coculture of pro-B lymphocytes with A, AB, B, or DN cells for 7 days, which were then assessed for the proportions of B-lymphocyte populations by FACS or transferred onto OP9 cells for an additional 7 days. (K) The proportions of pro-B, pre-B, and IgM+ B lymphocytes after 7 days of coculturing pro-B lymphocytes with A (n = 7), AB (n = 15), B (n = 9), or DN (n = 15) cells. (L) The proportions of pro-B, pre-B, and IgM+ B lymphocytes after coculturing pro-B lymphocytes with A, AB, B, or DN cells for 7 days, followed by 7 days coculture with OP9 cells. Data are shown only for cultures that produced B lymphocytes: A (n = 4), AB (n = 8), B (n = 6), or DN (n = 4). (M) The proportions of wells containing B lymphocytes after 7 days coculture with A, AB, B, and DN cells, and then 7 days after transfer onto OP9 cells. (N) Schematic showing coculture of pre-B lymphocytes with A, AB, B, or DN cells for 7 days, which were then analyzed for the proportions of B-lymphocyte populations. (O-P) The numbers of viable pre-B lymphocytes (O) and IgM+ B lymphocytes (P) after 7 days of coculture with pre-B lymphocytes with A (n = 5), AB (n = 9), B (n = 12), or DN (n = 16) cells. One-way ANOVA with Tukey’s multiple comparisons test: *P < .05; **P < .01; ***P < .001; ****P < .0001. C, calvaria; L, long bones; V, vertebrae.