Migration and differentiation of bone marrow lymphocytes: development of surface immunoglobulin, Fc receptor, complement receptor, and functional responsiveness as studied with anti-allotype serum

Clonal persistence of B lymphocytes in normal mice is determined by variable region-dependent selection

Many adult splenic B cells die within 1 week in the spleen of adoptive adult recipient mice; in contrast, the cellular environment of newborn recipients allows for their expansion and persistence for several weeks. In the present study, we show that the local environment of adult peritoneal cavity also allows adult splenic B cells to persist for over 2 weeks after intraperitoneal transfer. In order to determine whether the persistence of donor B cells in newborn hosts and in the peritoneum of adult recipients results from a selection process involving the clonal specificities expressed, the variation in time of VH gene family repertoires of donor B cells was analyzed in the hosts. At different times after the transfer of splenic cells from lipopolysaccharide (LPS)-reactive mice into LPS-non responder histocompatible recipients, mRNA colony blot assays were performed. The results show that among the donor adult LPS-reactive B cells, the VH genes are differently used by the expanding or persisting B cells, in both kinds of recipients. Thus, cells expressing J558 or VH11 gene families are, in particular, positively selected, while those expressing D-proximal or J606 and 36-30 VH gene families are less selected. These findings demonstrate that the propensity of B cells to persist and expand is determined by their selection through their immunoglobulin variable regions, rather than by genetic properties linked to particular B cell subsets.

Accumulation of bromodeoxyuridine-labeled cells in central and peripheral lymphoid organs: minimal estimates of production and turnover rates of mature lymphocytes

Daily lymphocyte production in both central and peripheral lymphoid organs was evaluated by associating in vivo incorporation of bromodeoxyuridine (BrdUrd) with cell surface labeling and multi-parameter flow analysis. At least 10% of mature T and B lymphocytes are generated every 24 h. The kinetic behavior of these cell populations differs, however, in that mature B cells are generated predominantly in the precursor compartments of the bone marrow, while most mature T cell generation occurs at the periphery. Therefore, peripheral expansion is the major mechanism of mature T cell production in the adult mouse. By following the accumulation of BrdUrd-labeled cells in peripheral lymphoid organs we found that the progeny of the daily lymphocyte production was sufficient to renew 30%-40% of all peripheral T and B cells every 48 h, demonstrating a high turnover rate of mature lymphocytes. We also examined the conditions of BrdUrd labeling of cycling cells in vivo. We found that while greater than 90% of bone marrow and thymus cells in S phase were labeled with a single injection of BrdUrd, in peripheral lymphoid compartments 70% of T and B cells in S failed to incorporate BrdUrd. Particular schedules of BrdUrd administration were required to overcome the low labeling efficiency of mature cells in vivo. Prolonged BrdUrd administration, however, had toxic effects on resident cells. The low labeling efficiency of BrdUrd incorporation by mature cells, as well as its potential toxicity during prolonged administration, may explain controversial results obtained by the different strategies used to study lymphocyte population dynamics.

Phenotype and proliferation of early B lymphocyte precursor cells in mouse bone marrow

Bone marrow cells were examined by double immunofluorescent labeling techniques to detect determinants for the B lineage monoclonal antibody, 14.8, the nuclear enzyme, terminal deoxynucleotidyl transferase (TdT), cytoplasmic mu chains (c mu), and surface mu (s mu). In 8-9-wk-old C3H/HeJ mice, 14.8+ cells totalled 22.2% of all marrow cells (35 X 10(5) cells/femur). While many 14.8+ cells were c mu+ s mu- pre-B cells and s mu+ B lymphocytes (17.0%), the remainder (5.2%) were large cells lacking mu chains. After injecting vincristine sulfate, these 14.8+ mu- cells accumulated in mitosis at a rate of 13.5%/h (turnover time, 7.4 h). Their calculated total production rate (41 X 10(6) cells/whole marrow/d) exceeded that previously determined for large pre-B cells, suggesting some cell loss from the B lineage. TdT+ cells made up 1.8% of marrow cells and were mainly medium-sized cells. They all lacked mu chains, but half (0.9%) bound 14.8 antibody at low to medium intensity. Three discrete cell populations were thus defined, differing in mean cell diameter TdT+ 14.8- mu-, 9.5 micron; TdT+ 14.8+ mu-, 10 microns; and TdT- 14.8+ mu-, 11.5 micron, presumptively representing a sequence of cell stages preceding the expression of mu chains in large pre-B cells (TdT- 14.8+ c mu+ s mu-, 11.5 microns). This work provides a tentative model of early progenitor cells and their proliferation in normal marrow as a basis for studies of perturbations and the control of B lymphocytopoiesis.

Population dynamics of bone marrow B lymphocytes

The dynamic concepts of lymphocyte populations which heralded the era of modern cellular immunobiology have been generally substantiated by recent studies and are still being correlated with functional properties. B lineage cells in the bone marrow are dynamically heterogeneous: A large majority are newly-formed, rapidly renewed cells, continuously produced from precursor cells within the bone marrow and disseminated during a terminal maturation phase via the blood stream. These cells develop low densities of sIgM in the extravascular bone marrow parenchyma and may undergo some further maturation within bone marrow sinusoids. The rate of production of bone marrow B cells appears to depend partly on the total load of exogenous agents to which the individual is exposed. Bone marrow lymphocyte production maintains a population of rapidly renewed virgin B cells in the peripheral lymphoid tissues. A small proportion of these cells apparently may be selected to enter a long-lived pool of B cells if suitably activated. By continuously creating novel clonotypes this process potentially can anticipate new antigen challenges and allow the immune system to build up a repertoire of antigen specificities most appropriate to the individual's changing environment throughout life. A minority of B lymphocytes in the bone marrow comprises slowly renewed, long-lived cells which enter and leave the bone marrow parenchyma as a selective part of the recirculating lymphocyte pool in the blood stream. Their role in the bone marrow is unknown. They include antigen-specific B memory cells, yet these are not activated within the bone marrow itself. No regulatory role has yet been directly demonstrated. Recently activated B cells enter from the spleen after secondary antigenic stimulation to develop into antibody-producing cells within the bone marrow. In assessing the significance of any phenotypically or functionally distinct B cell subset in the bone marrow, a basic consideration is to assign the subset to one of the foregoing dynamic categories. Within a given category cells may represent one stage in a time sequence of development. The bone marrow also produces lymphocytes of as yet uncertain lineage and contains selected subsets of T cells. The roles of these cells in cytotoxic, regulatory, or other events remain to be elucidated.

Lymphocyte population kinetics in the mouse

In a normal dynamic equilibrium, at least half of the peripheral T-cell pool is constituted by lymphocytes which have divided 24-48 h previously, and are therefore rapidly renewed. The renewal of peripheral T cells occurs partly by influx of cells from the thymus and, more importantly, by cell division at the periphery. The cyclic pattern of decay observed for T cells after HU treatment suggests the presence of progenitor-descendent relationships within the peripheral T-cell pool. Peripheral progenitors must contain both cycling and non-cycling cells to account for cell recovery after HU administration in ATx mice. T-cell production at the periphery involves both organized (spleen or lymph nodes) as well as non-organized lymphoid tissue (GALT). The latter may in fact provide the major contribution. Expansion of mature T lymphocytes contributes to clonal persistence at the periphery and to the choice of T-cell repertoires. The importance of post-thymic selection of T-cell repertoires is suggested by the considerable expansion potential revealed by peripheral T cells.