Maturation of bone marrow lymphocytes. II. Development of Fc and complement receptors and surface immunoglobulin studied by rosetting and radioautography.

Abstract

Radioautographic DNA labeling and rosetting techniques were combined to study the development of surface IgM, Fc, and complement receptors (FcR, CR) on small lymphocyte populations in mouse bone marrow. [3H]thymidine was either infused continuously to label newly formed cells for periods up to 4 days, or injected daily, 21--35 days before use, to label a sample of long-lived cells. Bone marrow cells were incubated with sensitized sheep erythrocytes to detect surface IgM, FcR, and CR, respectively, and examined radioautographically after cytocentrifugation. During [3H]thymidine infusion, marrow small lymphocytes lacking surface markers were the first to show [3H]thymidine labeling. Most of these cells became labeled by 4 days (IgM--ve, 89%; FcR--ve, 92%; Cr--ve, 88%). Labeling of small lymphocytes bearing surface IgM, FcR, and Cr began after an initial lag and increased to high values by 4 days (IgM + ve, 73%; FcR + ve, 82%; CR + ve, 83%). Labeled IgM + ve small lymphocytes formed progressively larger rosettes as cell age increased. Some proliferating large lymphoid cells formed rosettes for IgM, FcR, and CR. Labeled long-lived small lymphocytes expressed surface IgM, FcR, and CR, the incidence of each receptor being uniformly high (38--43%) and the rosettes tending to be larger than those formed by newly formed lymphocytes. In double-surface marker studies, FcR and CR rosettes were formed by some IgM--ve small lymphocytes as well as IgM + ve cells in the marrow. After transfusion of marrow cells from donor mice infused with [3H]thymidine for 24 h, many labeled newly formed lymphocytes homed into the splenic red pulp of unlabeled syngeneic recipients. Subsequently, these cells showed a rapid increase in the incidence of rosettes for surface IgM, FcR, and CR, together with a progressive enlargement of each type of rosette. Although all the labeled small lymphocytes recovered from the spleen developed both surface IgM and FcR by 3 days, only approximately one-half developed CR. The results demonstrate that most of the small lymphocytes bearing FcR, CR, and surface IgM in mouse bone marrow are newly formed indigenous cells. Each receptor becomes detectable by rosetting soon after the small lymphocytes are first produced. The newly formed, marrow-derived small lymphocytes are able to continue their development of surface IgM, FcR, and CR after migrating into the spleen, consistent with a maturation of primary B lymphocytes. In addition, the data indicate the genesis in mouse marrow of a non-B lineage of lymphocytes (notably, IgM--ve FcR + ve cells.). A minority of small lymphocytes bearing IgM, FcR, and CR in mouse marrow are long-lived cells, presumptive recirculating immigrants, differing in receptor status from the newly formed cells. The results are discussed with regard to the heterogeneity of marrow lymphocytes and proposed models of primary B lymphocyte and null lymphocyte production.

Population Dynamics of Bone Marrow B Lymphocytes

“…Kinetic analyses of small lymphocyte populations bearing other surface markers of mature B lymphocytes confirm that the majority of such cells are rapidly renewing and demonstrate a sequential expression of components on individual cells, at and following the time of expression of sIgM. Combined labeling with ^Hthymidine and cytocentrifuge rosetting techniques (Yang et al 1978), to quantitate surface membrane components, have shown that 75-85% of small lymphocytes bearing Ia antigens, Fc receptors (FcR) and complement receptors (CR) are rapidly renewing cells (t'A, 24-27 h), which first express these markers after a post-mitotic lag period. The dynamics of subsets of cells characterized by combinations of more than one marker on individual cells have also been defined by 'H-thymidine labeling of cell fractions (Chan & Osmond 1979).…”

“…Other commonly used assays for lymphocyte longevity involve transfer of identifiable cells into either normal or immunodeficient adoptive host animals (Yang et al 1978, Yoshida & Osmond 1978, Freitas et al 1982, Ron & Sprent 1985, Park et al 1985. While these techniques can indicate the potential hfe spans and phenotypic changes with age of the transferred cells under the conditions of the experiment, they cannot define the normal population kinetics of the lymphocytes in the intact immune system in vivo.…”

“…Bone marrow small lymphocytes can be divided into 2 kinetic populations with respect to IgM expression. Small lymphocytes with no detectable sIgM become rapidly labeled after the onset of ^H-thymidine administration (t'A, 17 h) and are extensively labeled (=^90%) by 2-3 d (Osmond & Nossal 1974, Yang et al 1978, Chan & Osmond 1979. They are thus immediately post-mitotic cells, mainly having a short turnover time in this phenotypic compartment but corresponding, nevertheless, to an exponential renewal pattern.…”

“…The cells pass in large numbers to the spleen, in smaller numbers and with a 1to 2-d lag to the lymph nodes, and rarely to the corticomeduUary junctional region of the thymus (Brahim & Osmond 1970). Transfusion of bone marrow cells labeled with ^H-thymidine to follow the fate of a cohort of newly-formed cells in unlabeled recipient mice also demonstrates a rapid localization of young small lymphocytes in the spleen (Yang et al 1978, Yoshida & Osmond 1978. Here, the immature B lymphocytes continue their development.…”

The bone marrow perisinusoidal niche for recirculating B cells and the positive selection of bone marrow‐derived B lymphocytes

“…In conventional secondary lymphoid organs such as the spleen, lymph nodes and Peyer's patches, these B cells are drawn into well‐defined B‐cell areas or follicles by CXCL13 secreted by follicular dendritic cells. The presence of IgD hi B cells in the bone marrow, often referred to as recirculating B cells, has been recognized for decades 4 , 5 but only recently has it been established that these B cells are actually extravascular in location, recirculate freely and that they occupy a unique perisinusoidal niche in the bone marrow, clustered around vascular sinusoids in the bone marrow 6 . Although follicular B cells are supported in the conventional follicular niche by follicular dendritic cells secreting the tumor necrosis factor family member B cell activating factor of the TNF family (BAFF), the survival of these very same B cells when they reside in the bone marrow perisinusoidal niche is mediated not by follicular dendritic cells (FDCs) and BAFF but by bone marrow dendritic cells that secrete macrophage migration inhibitory factor 7 .…”