Identification of Marrow-Derived and Thymus-Derived Small Lymphocytes in the Lymphoid Tissue and Thoracic Duct Lymph of Normal Rats

Abstract

All the specific radiosensitive cells required for the induction and expression of the primary antibody response to sheep erythrocytes in the rat are normally present among the small lymphocytes in thoracic duct lymph (1, 2). Experiments with radiation chimeras have now made it clear that the activity of thoracic duct cells in this response is due to the presence in rat lymph of two populations of small lymphocytes, one derived from the thymus (T lymphocytes) 1 and the other derived from the bone marrow without thymic influence (B lymphocytes).2 Thymus-marrow collaboration in the rat, first reported by Johnston and Wilson (3), is similar to that originally described in mice by Mitchell and Miller (4).The present work extends the earlier findings on radiation chimeras by demonstrating that thymus-and marrow-derived small ]ymphocytes are present in the thoracic duct lymph of normal rats, and establishes three criteria by which the two populations may be distinguished. These are: (a) a marked deficiency of uridine incorporation in vitro by B lymphocytes relative to T lymphocytes; (b) a small difference in the rate of sedimentation; (c) a physiological segregation after transfusion into the blood, into clearly distinct zones within the spleen, lymph nodes, and Peyer's patches, which define the areas through which the two cell populations recirculate. Materials and MelhodsAnimals.--Young adult male and female rats of the inbred HO and AO strains were used in this study.Collection from the Tlzoracic Dztct of Pure Marrow-Derived Lymphocy/es and Artificial Mixtures of ~Iarrow-Derived and T Lymphacyles.--Adult rats were thymectomized, irradiated with 1000 rads from a 6°Co source, and then injected intravenously with 10 7 bone marrow cells from 1 Abbreviations used in this" paper: B ]ymphocytes, peripheral bone marrow-derived small lymphocytes; DAB, Dulbecco's A q-B (buffered salt solution); D/E/FCS, fetal calf serum in Dulbecco's modified Eagle's medium; PBS, phosphate-buffered saline; T Iymphocytes, peripheral thymus-derived small ]ymphocytes.2 Scott, D. W., and J. C. Howard. Collaboration between thymus-derived and marrowderived thoracic duct lymphocytes in the hemolysin response of rat.

Anatomical Distribution of T and B Lymphocytes in the Rat

“…The origin of these marginal zone lymphocytes is not known, but there is evidence for two possible sources. Howard et al (11) and Sprent (18) have shown that B lymphocytes continuously recirculate from the blood to the follicular region of splenic white pulp. The route followed has not yet been determined; it is conceivable, however, that it lies along a pathway that includes blood sinuses in the marginal zone.…”

“…B lymphocytes have been distinguished from T lymphocytes by their buoyant density, decreased rate of incorporation of RNA precursors, and propensity to migrate to the "thymus-.ndependent" areas of peripheral lymphoid tissue (10,11). 1…”

Anatomy of germinal centers in mouse spleen, with special reference to "follicular dendritic cells"

“…All macrophages in the GC have large, densely staining, phagocytic inclusions called tingible bodies (T). The mantle contains many small lymphocytes (SL), probably recirculating B cells (12,18). Macrophages (MAC) are present, though only a minority contain tingible bodies.…”

“…1 and 11). The latter consisted mainly of small lymphocytes (probably recirculating B cells [12,18]), as well as scattered lymphoblasts, macrophages, plasma cells, and cells which we termed FDC's. The mantle and GC proper together were referred to as a secondary follicle.…”

Lymphocyte Subsets and Mitogen Induced Proliferation in Adjuvant Arthritis. Part I. Migration and Function of the Peripheral T Lymphocytes.

“…The migrations of lymphocytes were specific to subtypes and microenvironment (Ford and Simmomds 1972 ;Howard et al 1972 ;Haynes and Fauci 1978) and were influenced by steroid, antigen, and genetic factors (Ford 1972;Moorhaed and Claman 1972;Bona 1979). It was suggested that the circulating lymphocytes were more adherent to the target tissue ; this binding between lymphocytes and target tissue thus controls the migratory pattern of lymphocytes from peripheral blood to the organized lymphoid organs such as lymph nodes (Jalkanen et al 1986).…”