Re-utilization of lymphocytes in lymphopoiesis

The in vivo reutilization of lymphocytic and sarcoma DNA by cells growing in the peritoneal cavity

An ascites tumor, Sarcoma I, was transplanted to isologous and homologous mice which had been labeled with tritiated thymidine from 1 to 24 hours previously. Radioautographic preparations revealed labeled host lymphocytes emerging to mingle with the transplanted tumor and the subsequent appearance of nuclear radioactivity in the sarcoma. Sarcoma cells cultured subcutaneously or in Millipore diffusion chambers in previously labeled mice did not demonstrate significant radioactivity. Transplantation of washed, H³-thymidine-labeled lymphocytes to non-radioactive, sarcoma-bearing mice was followed by the gradual appearance of nuclear radioactivity in the sarcoma. The label in the sarcoma was entirely removed by deoxyribonuclease but not by ribonuclease treatment prior to radioautography. Intraperitoneal injections of purified, H³-thymidine-labeled sarcoma or lymphoid DNA in normal or tumor-bearing mice were followed by radioactivity appearing in sarcoma or normal peritoneal mononuclear cells. It was concluded that reutilization of DNA and its metabolites may occur in vivo, and the conditions under which reutilization may be detected are discussed.

Transformation of adult allogeneic small lymphocytes after transfusion into newborn rats

Newborn rats of one inbred strain were given an intracardiac injection of adult thoracic duct lymphocytes from another inbred strain. It was found that although there was a direct relationship between the number of small lymphocytes injected and the incidence of fatal runt disease, there was no particular relationship between the large lymphocyte content of an inoculum and its runt-inducing potentiality. Using tritiated thymidine and an autoradiographic technique, the small lymphocytes in the inoculum were labelled and found to migrate in large numbers into the cortex of the lymph nodes and into the Peyer's patches of the host animal, and in smaller numbers into the white pulp of the spleen. Within 24 hours isotope, previously present in the DNA of small lymphocytes, appeared in a number of the large pyroninophilic cells which were a characteristic feature of the spleen and lymph nodes in this early phase of runt disease. When the large lymphocytes in the inoculum were labelled they were found to migrate to the red pulp of the spleen, medulla of the lymph nodes, and the Peyer's patches and the lamina propria of the small intestine. Later some labelled small lymphocytes appeared at these sites. These findings suggest that: (1) Some small lymphocytes are immunologically competent cells, and (2) After introduction into the circulation of a newborn rat, these same small lymphocytes are the first cells to react with the antigens of the host, and in the process they become transformed into large pyroninophilic cells capable of division. The large lymphocytes seem to play little part in this initiating of an immunological response, but do give rise to some small lymphocytes.

Quantitativ studies on small lymphocyte disposition in epithelial cells

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The effects of varying dosages of irradiation on benign and malignant pelvic lymph nodes

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The fine structure of lymphatic tissue germinal centers. Reticular remnant after injury

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The uptake of tritium-labelled thymidine by lymphoid tissue

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