Radioautographic studies of small lymphocytes in the thoracic duct of the rat

Bone marrow origin of immunologically competent lymphocytes in the rat

Rat bone marrow is deficient in immunologically competent cells when compared with the peripheral pool of circulating small lymphocytes. However, circulating lymphocytes capable of initiating a lethal graft vs. host reaction can develop from myeloid precursors. In adult rats inoculated at birth with parental strain bone marrow cells, the thoracic duct lymph contains cells having the immunological capability of the marrow donor. The evidence suggests that immunologically competent lymphocytes derive from cells normally resident in bone marrow and probably not from precursors in the peripheral lymphocyte pool.

Chronic thoracic duct fistula: operative technic and physiologic effects in man

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Studies on the leukocytosis and lymphocytosis induced by Bordetella pertussis. I. Radioautographic analysis of the circulating cells in mice undergoing pertussis-induced hyperleukocytosis

By the use of radioautographic techniques it was shown that the lymphocytosis induced by Bordetella pertussis in mice was not caused by an increased production of lymphocytes but was primarily due to the entry into the circulation of mature cells from tissue pools. The accompanying polymorphonuclear leukocytosis was due to both proliferation of myeloid elements and entry of mature cells from tissue reserves, with the former the predominant mechanism.

The carriage of immunological memory by small lymphocytes in the rat

Lymphocytes were obtained from the thoracic duct of rats 1(1/2) to 15 months after primary immunization with a single dose of bacteriophage phiX 174. An intravenous injection of these lymphocytes conferred on heavily X-irradiated rats the ability to form antibody in a secondary-type manner after a first injection of phiX. Negligible responses were obtained after cell transfer if the recipients were not challenged with antigen. Thoracic duct cells from some immunized donors were incubated in vitro for 24 hr before transfer in order to destroy selectively the large, dividing lymphocytes. The responsiveness conferred on X-irradiated recipients by such "incubated" inocula was then compared with that given by equal numbers of "fresh" thoracic duct cells. In all such comparisons the recipients of the "incubated" cells gave higher and more rapid antibody responses. It was concluded that the cells in thoracic duct lymph which carried immunological memory were small lymphocytes.

The interaction of mycoplasmas with mammalian cells. II. Monocytes and lymphocytes

The incubation of mycoplasmas with human peripheral blood buffy coats resulted in the uptake of these microorganisms by more than 50% of the mononuclear cells. Mycoplasmas adhered to the plasma membranes of all leukocytes, most of which developed long cytoplasmic processes not seen in the controls. In human and rat thoracic duct lymph, about 6% of the cells ingested the microorganisms. T(2) phage and thorotrast were taken up by a similar percentage of lymphocytes. On morphological grounds, the cells which were able to take up PPLO's or particles could not be distinguished from the cells which were incapable of this function. Following phagocytosis, neither the cell nor the microorganism showed any morphological alterations over a 3 hr period of observation. The demonstration that a small percentage of "lymphocytes" are able to phagocytose may have pathological and immunological implications.

The origin and turnover of mononuclear cells in peritoneal exudates in rats

Tritiated thymidine-labeling data in individual and parabiotic rats showed that macrophages in peritoneal exudates were derived from cells in the blood which were the progeny of rapidly and continuously proliferating precursors. The characteristics of this population identify them with free macrophages studied in other sites; similarly, they can be obtained from transfused bone marrow. Cells in the exudates which were morphologically indistinguishable from small lymphocytes were also found to have the labeling features of a rapidly proliferating population in contrast with the known kinetics of the majority of small lymphocytes in blood and thoracic duct lymph. However, experimental evidence indicated that the lymphocytelike exudate cells had emigrated from the blood and that bone marrow was a source of their precursors. These findings support the concept of the heterogeneity of lymphocytes. The possible relationships among the mononuclear cells is discussed.

Thymus-dependent areas in the lymphoid organs of neonatally thymectomized mice

Specific areas of lymphocyte depletion, termed thymus-dependent areas, have been delineated in neonatally thymectomized C3H/Bi and F(1) (C57BL x C3H/Bi) mice. They occur within the lymphoid follicles of the spleen immediately surrounding the central arterioles, and constitute the mid and deep cortical zones of the lymph nodes. These depleted areas appear in healthy thymectomized mice as early as 3 wk after operation but, in mice which survive for more than 6 to 7 wk, the thymus-dependent areas are repopulated by rapidly dividing pyroninophilic cells, the majority of which are immature plasma cells. Syngeneic thymus cells, labeled in vitro with tritiated adenosine localize preferentially in the thymus-dependent areas after intravenous injection. Similarly labeled spleen cells also accumulate in these areas but, in addition, are distributed at the periphery of splenic follicles and in the outer cortical zone of the lymph nodes. Many more spleen than thymus cells enter the lymphoid tissues and the spleen appears to be the primary target. The apparent paradox that syngeneic thymus cells are less efficient than spleen cells in restoring neonatally thymectomized mice to normality is discussed in the light of these results and possible routes by which the migrating cells could enter the lymphoid tissues are considered. The origin of the plasma cells which repopulate the lymphocyte depleted areas is also discussed. It is concluded that the normal thymus produces cells which contribute directly to the migratory or circulatory lymphocyte population but that there also exists another source of supply for the plasma cell series. These two systems may function synergistically so that the thymus may control, directly or indirectly, the balance of cell populations within the body.

Role of the thymus in tolerance. I. Tolerance to bovine gamma globulin in thymectomized, irradiated rats grafted with thymus from tolerant donors

Rats thymectomized and irradiated as adults were restored to immunologic reactivity by grafts of normal adult rat thymus and bone marrow. Reactivity of the delayed (cellular) type and formation of mercaptoethanol-sensitive (MES) and mercaptoethanol-resistant (MER) antibody returned within 3 weeks, while Arthus reactivity remained subnormal till 9 weeks after irradiation and grafting. When the thymus donor was tolerant to BGG, the recipient showed specific non-reactivity to this antigen 3 weeks and, to a much lesser extent, 6 weeks after grafting. This non-reactivity affected delayed responses and MER antibody. No effect was noted on Arthus reactivity and a slight effect on MES antibody. Controls showed that the non-reactivity was not due to transfer of free antigen at the time of grafting. It was concluded that different source organs are responsible for different immune functions and that specific immunologic tolerance may be induced within such an organ as the thymus.