Figure 2. Mx1-Cre deletion of Asciz leads to B lymphopenia. (A) Blood cell content in ASCIZ-Mx controls and deleters, showing red blood cells (left) and lymphocytes (right) from 4 wk (w) to 12 mo (m) after poly(I:C) injection. Animal numbers: 4 wk, 31 controls/26 deleters; 8 wk, 31/26; 12 wk, 29/24; 16 wk, 30/22; 6 mo, 30/21; 9 mo, 28/23; and 12 mo, 27/22. Animals are from the same cohorts shown in Fig. 1 D with the control group comprised of Mx1-Cre+Ascizfl/+ and Mx1-Cre−Ascizfl/fl mice, with no differences between subgroups. Note that at all time points, differences between controls and deleters are P < 0.0001, except for red blood cells at 12 mo (P < 0.01). (B) Total blood B lymphocyte numbers (right) of ASCIZ-Mx controls and deleters and representative FACS plots (left) using B220 as a B cell marker and costaining for CD4 and CD8 conjugated to the same fluorophore as T cell markers. Results shown here were obtained at 4 wk after poly(I:C) injection. n = 13 for Mx1-Cre+Ascizfl/fl deleters, and n = 14 for pooled controls (n = 4 Mx1-Cre+Ascizfl/+ and n = 10 Mx1-Cre−Ascizfl/fl) with no difference between subgroups. (C) Representative FACS profiles for splenic B220+IgM+ B cell populations (boxed gates; left) and absolute numbers (right) of splenic B220+IgM+ cells in ASCIZ-Mx controls (n = 14; n = 8 Mx1-Cre+Ascizfl/+ and n = 6 Mx1-Cre Ascizfl/fl) and Mx1-Cre+Ascizfl/fl deleters (n = 5) at 4 wk after poly(I:C) injection. (D) Gating strategy (left) and total numbers of bone marrow B cell populations (right). The boxed B220+IgM+ population includes immature, transitional, and recirculating B cells, and the boxed B220+IgM− population is further gated for CD43 and CD19 to distinguish pro-B cells (CD43+CD19+) and pre-B cells (CD43−CD19+). Total numbers represent B cell populations in one hind limb of ASCIZ-Mx controls (n = 15; n = 9 Mx1-Cre+Ascizfl/+ and n = 6 Mx1-Cre−Ascizfl/fl) and Mx1-Cre+Ascizfl/fl deleters (n = 7) at 4 wk after poly(I:C) injection. (A–D) All data represent mean ± SEM. Each symbol in B and C represents one animal. Closed bars and circles indicate controls; open bars and circles indicate deleters. Data in B–D were obtained in at least two independent experiments. Similar results were obtained in mice sacrificed at 16 wk after poly(I:C) injection (not depicted).
Figure 2.

Mx1-Cre deletion of Asciz leads to B lymphopenia. (A) Blood cell content in ASCIZ-Mx controls and deleters, showing red blood cells (left) and lymphocytes (right) from 4 wk (w) to 12 mo (m) after poly(I:C) injection. Animal numbers: 4 wk, 31 controls/26 deleters; 8 wk, 31/26; 12 wk, 29/24; 16 wk, 30/22; 6 mo, 30/21; 9 mo, 28/23; and 12 mo, 27/22. Animals are from the same cohorts shown in Fig. 1 D with the control group comprised of Mx1-Cre+Ascizfl/+ and Mx1-Cre−Ascizfl/fl mice, with no differences between subgroups. Note that at all time points, differences between controls and deleters are P < 0.0001, except for red blood cells at 12 mo (P < 0.01). (B) Total blood B lymphocyte numbers (right) of ASCIZ-Mx controls and deleters and representative FACS plots (left) using B220 as a B cell marker and costaining for CD4 and CD8 conjugated to the same fluorophore as T cell markers. Results shown here were obtained at 4 wk after poly(I:C) injection. n = 13 for Mx1-Cre+Ascizfl/fl deleters, and n = 14 for pooled controls (n = 4 Mx1-Cre+Ascizfl/+ and n = 10 Mx1-Cre−Ascizfl/fl) with no difference between subgroups. (C) Representative FACS profiles for splenic B220+IgM+ B cell populations (boxed gates; left) and absolute numbers (right) of splenic B220+IgM+ cells in ASCIZ-Mx controls (n = 14; n = 8 Mx1-Cre+Ascizfl/+ and n = 6 Mx1-Cre Ascizfl/fl) and Mx1-Cre+Ascizfl/fl deleters (n = 5) at 4 wk after poly(I:C) injection. (D) Gating strategy (left) and total numbers of bone marrow B cell populations (right). The boxed B220+IgM+ population includes immature, transitional, and recirculating B cells, and the boxed B220+IgM− population is further gated for CD43 and CD19 to distinguish pro-B cells (CD43+CD19+) and pre-B cells (CD43−CD19+). Total numbers represent B cell populations in one hind limb of ASCIZ-Mx controls (n = 15; n = 9 Mx1-Cre+Ascizfl/+ and n = 6 Mx1-Cre−Ascizfl/fl) and Mx1-Cre+Ascizfl/fl deleters (n = 7) at 4 wk after poly(I:C) injection. (A–D) All data represent mean ± SEM. Each symbol in B and C represents one animal. Closed bars and circles indicate controls; open bars and circles indicate deleters. Data in B–D were obtained in at least two independent experiments. Similar results were obtained in mice sacrificed at 16 wk after poly(I:C) injection (not depicted).

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