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B cell development in the spleen takes place in discrete steps and is determined by the quality of B cell receptor-derived signals.

Loder F, Mutschler B, Ray RJ, Paige CJ, Sideras P, Torres R, Lamers MC, Carsetti R - J. Exp. Med. (1999)

Bottom Line: They develop into the transitional B cells of type 2 (T2), which are cycling and found exclusively in the primary follicles of the spleen.Mice with genetic deletions of elements participating in the B cell receptor signaling cascade display developmental arrest at the T1 or T2 stage.The analysis of these defects showed that the development of T2 and mature B cells from T1 precursors requires defined qualitative and quantitative signals derived from the B cell receptor and that the induction of longevity and maturation requires different signals.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Immunology, University of Freiburg, Germany.

ABSTRACT
Only mature B lymphocytes can enter the lymphoid follicles of spleen and lymph nodes and thus efficiently participate in the immune response. Mature, long-lived B lymphocytes derive from short-lived precursors generated in the bone marrow. We show that selection into the mature pool is an active process and takes place in the spleen. Two populations of splenic B cells were identified as precursors for mature B cells. Transitional B cells of type 1 (T1) are recent immigrants from the bone marrow. They develop into the transitional B cells of type 2 (T2), which are cycling and found exclusively in the primary follicles of the spleen. Mature B cells can be generated from T1 or T2 B cells. Mice with genetic deletions of elements participating in the B cell receptor signaling cascade display developmental arrest at the T1 or T2 stage. The analysis of these defects showed that the development of T2 and mature B cells from T1 precursors requires defined qualitative and quantitative signals derived from the B cell receptor and that the induction of longevity and maturation requires different signals.

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Kinetics of BrdU labeling of B lymphocytes of normal and mutant mice. Mice received BrdU (1 mg/ml) in their drinking water for the indicated times. Splenic B cell populations were identified on the basis of three different surface staining protocols: IgM vs. IgD, IgM vs. CD21, and IgD vs. CD22. The BrdU content of the cells was determined by flow cytometry. The experiments were repeated three times, and comparable results were obtained. The columns represent the percentages of BrdU-labeled B cells in normal and mutant mice analyzed 24 (stippled bars) and 72 h (gray bars) after the beginning of the BrdU administration. The percentage of B cells still labeled 18 d after a 3-d treatment with BrdU (18-d chase; black bars) is also shown. The absolute numbers of labeled B cells in the normal spleen were 2 × 106 after 24 h, 5.6 × 106 after 3 d, and 0.9 × 106 after the 18-d chase. In the CD45−/− mouse, 35 × 106 B cells were labeled after 24 h and 37.8 × 106 after 3 d. 0.8 × 106 B cells were still labeled after the 18-d chase. The CBA/N mouse had 2.4 × 106 labeled B cells on day 1 and 3.2 × 106 on day 3. Only 0.1 × 106 cells were still labeled after the chase.
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Figure 7: Kinetics of BrdU labeling of B lymphocytes of normal and mutant mice. Mice received BrdU (1 mg/ml) in their drinking water for the indicated times. Splenic B cell populations were identified on the basis of three different surface staining protocols: IgM vs. IgD, IgM vs. CD21, and IgD vs. CD22. The BrdU content of the cells was determined by flow cytometry. The experiments were repeated three times, and comparable results were obtained. The columns represent the percentages of BrdU-labeled B cells in normal and mutant mice analyzed 24 (stippled bars) and 72 h (gray bars) after the beginning of the BrdU administration. The percentage of B cells still labeled 18 d after a 3-d treatment with BrdU (18-d chase; black bars) is also shown. The absolute numbers of labeled B cells in the normal spleen were 2 × 106 after 24 h, 5.6 × 106 after 3 d, and 0.9 × 106 after the 18-d chase. In the CD45−/− mouse, 35 × 106 B cells were labeled after 24 h and 37.8 × 106 after 3 d. 0.8 × 106 B cells were still labeled after the 18-d chase. The CBA/N mouse had 2.4 × 106 labeled B cells on day 1 and 3.2 × 106 on day 3. Only 0.1 × 106 cells were still labeled after the chase.

Mentions: In normal mice, mature B cells are long lived, and recent splenic immigrant B cells from the bone marrow are short lived, with a life span of 3 d after their arrival in the spleen. Subsequently, they are either incorporated into the long-lived pool or eliminated 530. We determined the frequency and phenotypic distribution of short- and long-lived B cells in CD45 and Btk mutant mice using the BrdU labeling technique. Mice were analyzed 24, 72, and 120 h after the onset of the treatment. 24 h after the beginning of the BrdU administration, the fraction of labeled cells was 4% in the spleens of normal mice (Fig. 7) and rose to a maximal 16% after 3 d of continuous treatment. In CD45−/− and CBA/N mice, about half of the splenic B cells incorporated BrdU in 24 h. The percentage of labeled cells remained constant thereafter. Our results confirm the life span analysis of splenic B cells of normal mice but indicate that in mutant mice, labeled B cells have a life span of only 1 d.


B cell development in the spleen takes place in discrete steps and is determined by the quality of B cell receptor-derived signals.

Loder F, Mutschler B, Ray RJ, Paige CJ, Sideras P, Torres R, Lamers MC, Carsetti R - J. Exp. Med. (1999)

Kinetics of BrdU labeling of B lymphocytes of normal and mutant mice. Mice received BrdU (1 mg/ml) in their drinking water for the indicated times. Splenic B cell populations were identified on the basis of three different surface staining protocols: IgM vs. IgD, IgM vs. CD21, and IgD vs. CD22. The BrdU content of the cells was determined by flow cytometry. The experiments were repeated three times, and comparable results were obtained. The columns represent the percentages of BrdU-labeled B cells in normal and mutant mice analyzed 24 (stippled bars) and 72 h (gray bars) after the beginning of the BrdU administration. The percentage of B cells still labeled 18 d after a 3-d treatment with BrdU (18-d chase; black bars) is also shown. The absolute numbers of labeled B cells in the normal spleen were 2 × 106 after 24 h, 5.6 × 106 after 3 d, and 0.9 × 106 after the 18-d chase. In the CD45−/− mouse, 35 × 106 B cells were labeled after 24 h and 37.8 × 106 after 3 d. 0.8 × 106 B cells were still labeled after the 18-d chase. The CBA/N mouse had 2.4 × 106 labeled B cells on day 1 and 3.2 × 106 on day 3. Only 0.1 × 106 cells were still labeled after the chase.
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Related In: Results  -  Collection

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Figure 7: Kinetics of BrdU labeling of B lymphocytes of normal and mutant mice. Mice received BrdU (1 mg/ml) in their drinking water for the indicated times. Splenic B cell populations were identified on the basis of three different surface staining protocols: IgM vs. IgD, IgM vs. CD21, and IgD vs. CD22. The BrdU content of the cells was determined by flow cytometry. The experiments were repeated three times, and comparable results were obtained. The columns represent the percentages of BrdU-labeled B cells in normal and mutant mice analyzed 24 (stippled bars) and 72 h (gray bars) after the beginning of the BrdU administration. The percentage of B cells still labeled 18 d after a 3-d treatment with BrdU (18-d chase; black bars) is also shown. The absolute numbers of labeled B cells in the normal spleen were 2 × 106 after 24 h, 5.6 × 106 after 3 d, and 0.9 × 106 after the 18-d chase. In the CD45−/− mouse, 35 × 106 B cells were labeled after 24 h and 37.8 × 106 after 3 d. 0.8 × 106 B cells were still labeled after the 18-d chase. The CBA/N mouse had 2.4 × 106 labeled B cells on day 1 and 3.2 × 106 on day 3. Only 0.1 × 106 cells were still labeled after the chase.
Mentions: In normal mice, mature B cells are long lived, and recent splenic immigrant B cells from the bone marrow are short lived, with a life span of 3 d after their arrival in the spleen. Subsequently, they are either incorporated into the long-lived pool or eliminated 530. We determined the frequency and phenotypic distribution of short- and long-lived B cells in CD45 and Btk mutant mice using the BrdU labeling technique. Mice were analyzed 24, 72, and 120 h after the onset of the treatment. 24 h after the beginning of the BrdU administration, the fraction of labeled cells was 4% in the spleens of normal mice (Fig. 7) and rose to a maximal 16% after 3 d of continuous treatment. In CD45−/− and CBA/N mice, about half of the splenic B cells incorporated BrdU in 24 h. The percentage of labeled cells remained constant thereafter. Our results confirm the life span analysis of splenic B cells of normal mice but indicate that in mutant mice, labeled B cells have a life span of only 1 d.

Bottom Line: They develop into the transitional B cells of type 2 (T2), which are cycling and found exclusively in the primary follicles of the spleen.Mice with genetic deletions of elements participating in the B cell receptor signaling cascade display developmental arrest at the T1 or T2 stage.The analysis of these defects showed that the development of T2 and mature B cells from T1 precursors requires defined qualitative and quantitative signals derived from the B cell receptor and that the induction of longevity and maturation requires different signals.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Immunology, University of Freiburg, Germany.

ABSTRACT
Only mature B lymphocytes can enter the lymphoid follicles of spleen and lymph nodes and thus efficiently participate in the immune response. Mature, long-lived B lymphocytes derive from short-lived precursors generated in the bone marrow. We show that selection into the mature pool is an active process and takes place in the spleen. Two populations of splenic B cells were identified as precursors for mature B cells. Transitional B cells of type 1 (T1) are recent immigrants from the bone marrow. They develop into the transitional B cells of type 2 (T2), which are cycling and found exclusively in the primary follicles of the spleen. Mature B cells can be generated from T1 or T2 B cells. Mice with genetic deletions of elements participating in the B cell receptor signaling cascade display developmental arrest at the T1 or T2 stage. The analysis of these defects showed that the development of T2 and mature B cells from T1 precursors requires defined qualitative and quantitative signals derived from the B cell receptor and that the induction of longevity and maturation requires different signals.

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