Rat Lymphoid Organs Research Articles

Plasma renin and erythropoietic activity after deduction of the extracelular volume

In the thymus, spleen and bone marrow of adult guinea pigs, 14--30-week human fetuses, and the peripheral blood of sterile men there were found cells capable of forming the rosettes with homo- or heterologous spermatozoa (RFC). Development of autoimmune orchitis after the trauma of the rat testis or after the guinea pig immunization with the testicular homogenate mixed with complete Freund's adjuvant caused the appearance of RFC with spermatozoa in the thymus and the spleen of rats, and an increase of their number in the lymphoid organs of guinea pigs. Such treatment did not influence the quantity of sheep-cell rosettes in the lymphoid organs of rats and guinea pigs. A possibility of using the detected capacity of animal and human lymphocytes to form spontaneous and immune rosettes with the spermatozoa to test the degree of lympocyte differentiation and their sensitisation to the spermatozoa antigens after the spermatogenesis distrubances of the autoimmune nature is discussed.

Rat T Lymphocyte-Specific Antigens and Their Cross-Reactivity with Mouse T Cells

Anti-rat T lymphocyte serum (ATLS)2 was prepared by immunizing rabbits with purified T cells from rat mesenteric nodes and absorbed with rat red cells and syngeneic sarcoma cells. The specificity of ATLS for rat T cells was confirmed by the following reasons: a) ATLS was not toxic for bone marrow cells but lysed most of the thymocytes and a number of spleen and lymph node cells, which were inversely correlated to the percentage of cells with B cell characteristics in respective organs; b) anatomical localization of ATLS-reactive cells in lymphoid organs coincided to the thymus-dependent areas, i.e. the paracortex of lymph node and the periarteriolar region of spleen; c) spleen cells treated with ATLS and complement failed to respond to phytohemagglutinin but normally responded to bacterial lipopolysaccharide; d) those cells treated with ATLS and complement could not induce a graft-vs-host reaction in F1 hosts, whereas the same treatment did not affect direct plaque-forming cells. All of these data confirm the specificity of ATLS and indicate that ATLS recognizes rat T lymphocyte-specific antigens (RTLA). Absorption studies showed that RTLA were present in higher concentration on medullary thymocytes and peripheral T cells than on cortical thymocytes, but absent from bone marrow, liver, and brain tissues. When the cross-reactivity of RTLA with mouse T cells was studied by C-dependent cytotoxicity and immunofluorescence, it was found that mouse T cells shared at least one determinant of RTLA with rat T cells, and that distribution pattern of the cross-reacting antigens in mouse lymphoid tissues was essentially the same as that of RTLA in rat lymphoid organs.

Selective effect on T and B cell subpopulations in rat lymphoid organs after urethan treatment.

In vitro phytohemagglutinin (PHA) and concanavalin A (Con A) responsiveness of thymus and bone marrow cells, and E, EA, and EAC rosette-forming cells (E, EA, EAC) of these organs and spleen were studied in Fisher rats at various time intervals following a carcinogenic treatment with urethan (UR). Immediately after treatment, organ cellularities were drastically reduced with a progressive recovery as time passed. 1 day after treatment, the response of thymocytes to PHA showed a fourfold increase while organ cellularity dropped to 1%. This response fell below normal values after 7 days with an overshoot after days 14 and 21. UR-treated bone marrow cells showed a response to PHA below normal values after 1 and 7 days, a twofold increase after 3 days and an overshoot after 14 and 21 days. The responsiveness to Con A of both organs was affected by UR treatment to a much lesser extent, although following a pattern similar to that of PHA. E were never found, whether in normal nor in UR-treated animals. As far as the B-cell compartment is concerned, UR causes a progressive diminution of EAC, while the number of EA remains unaffected. The data are discussed in terms of selective effect on T- and B-cell subpopulations.

Characterization of the normal lymphocyte population cytolytic to Burkitt's lymphoma cells of the EB2 cell line.

The normal human lymphocyte population which exhibits "spontaneous" cytolysis of EB2 Burkitt's lymphoma cells has been characterized. The effector cell has EA and EAC' receptors but lacks E receptors and probably surface Ig. "Spontaneous" anti-EB2 cytotoxicity was not reduced by preincubation of the effector cells with plastic or iron carbonyl or by passage through cotton wool or agarose columns but was reduced by passage through nylon wool columns. Thymocytes were not cytotoxic to EB2 cells, and chronic lymphocytic leukaemia cells (of B cell characteristics) had reduced cytotoxicity compared with normal lymphocytes. Cells from various lymphoid organs of rats and guinea-pigs were also cytotoxic to EB2 cells with reactivity in spleen greater than or equal to blood greater than lymph nodes. Spleen cells from neonatally thymectomized rats had increased cytotoxicity compared with normal rat spleen cells, suggesting that T lymphocytes are not essential. The effector cell in rat spleen did not adhere to cotton wool or agarose columns, indicating some resemblance to its counterpart in human peripheral blood.

Comparative Studies of Immunoglobulin Receptors and Antibody-Dependent Cell Cytotoxicity (ADCC) in Rat Lymphoid Organs

Abstract The capability of rat lymphoid cells to destroy antibody-coated target cells (antibody-dependent cell cytotoxicity, ADCC) and to form rosettes with immunoglobulin-coated erythrocytes (EA) was compared. Because both processes require binding of a lymphoid cell to antibody associated with cellular antigen, we undertook to determine if both assays detect the same cell population. Peripheral blood lymphocytes, spleen and lymph node cells had both activities, but there was no correlation between the number of rosettes and the ADCC activity. Blood lymphocytes had the highest cytotoxic potential, while spleen cells produced the highest percentage of rosettes. Bone marrow cells were devoid of cytotoxic activity though many of the cells were able to form rosettes. Thymus cells were neither cytotoxic nor able to form rosettes. Following treatment of spleen cells with 1) anti-rat Ig serum, 2) high concentrations (τ1 mg/ml) of trypsin and Pronase (but not papain), or phospholipase-C, the number of rosettes was strongly diminished, whereas the cytotoxic activity was unimpaired. The ADCC activity was not altered after removal of 60% of the rosetteforming cells by nylon column, but was greatly reduced when 85% of the rosette-forming cells were removed by anti-SRBC serum. These observations indicate that: 1) there is no correlation between the percentage of EA rosette-forming cells and the ADCC activity in various lymphoid tissues, 2) these activities were not equally susceptible to enzymes' action, 3) the cytotoxic activity is mediated by a subpopulation of the EA rosette-forming cells, and 4) probably fewer immunoglobulin receptor sites per unit surface membrane are required for ADCC cytotoxicity than for rosette formation.

A comparison of the activation of thymus and lymph-node cells by concanavalin-A and phytohaemagglutinin. Effects of complement

Cell suspensions from rat lymphoid organs were incubated for 6 hr with 3H-uridine in either bovine calf serum or homologous serum. The radioactive labelling of acid-precipitable material was then measured. Calf serum greatly inhibited the labelling of thymus cells, but had only a small effect on lymph-node cells. The inhibition was removed by decomplementing serum suggesting that cell destruction had been initiated by specific complement-fixing natural antibodies against rat thymus determinants. Activation of lymphocytes was assessed by measuring the enhancement of labelling produced by concanavalin-A (Con-A) or phytohaemagglutinin )PHA). In homologous serum and in decomplemented calf serum, thymus cells were activated by Con-A, (i) more than by PHA, and (ii) less than lymph-node cells were activated by Con-A. The latter finding indicates that the reduced transformation response of thymus cells to Con-A reported by other workers reflects the failure of cell activation, rather than of cell survival in vitro. In calf serum, lymph-node cells were activated by low concentrations of Con-A and inhibited by high concentrations of Con-A; the latter reaction required complement. In calf serum, thymus cells were (i) inhibited by Con-A concentrations low enough to stimulate lymph-node cells, and (ii) stimulated by low PHA concentrations. The results suggest that thymus cells consist of at least two populations, a major population destroyed by calf serum and activated by Con-A but not by PHA, and a minor population which is activated by PHA but not by Con-A. Attention is drawn to discrepancies between the Con-A dose-response relationships described by different workers. These may be understood in terms of the changing pattern of dose-response curves with time of culture, which is described elsewhere (Milthorp and Forsdyke, 1973).

Vitamin C in lymphoid organs of rats and cockerels treated with corticosterone or testosterone.

Immature rats and cockerels were injected for 14 days with 0.05-5.0 mg of testosterone propionate or corticosterone, and the concentration and oxidation state of vitamin C in their lymphoid organs was measured. The total vitamin C concentration (ascorbate + dehydroascorbate) in the lymphoid organs of both animals decreased after hormone administration, but to a greater extent in rats than in cockerels. These changes appear to be independent of any direct hormonal influence on vitamin C biosynthesis. Significant and marked changes in the oxidation state of lymphoid organ vitamin C occurred after lympholytic steroid hormone treatment; the percentage of dehydroascorbate increased and that of ascorbate decreased. After hormone treatment the largest percentage change from controls (more than 100% increases in percentage dehydroascorbate) occurred in the central lymphoid organs, the bursa and thymus, rather than in the spleen or lymph nodes. Much lower dose levels of corticosterone (0.05 mg) than of testosterone propionate (5.0 mg) were required to produce this shift in the oxidation state of lymphoid organ vitamin C. We suggest the ascorbate-dehydroascorbate system in the lymphoid organs is an integral portion of the physiological mechanisms operative during hormonal modulation of the growth, metabolism, and function of the lymphoid organs.

Impaired Activation of Thymus Lymphocytes by Phytohemagglutinin

Abstract Activation of lymphocytes was assessed by measuring the enhanced labeling with 5-3H-uridine of cell suspensions from various rat lymphoid organs produced by phytohemagglutinin (PHA) in a 4-hr period. No evidence was obtained for reduced function of thymus cells when compared with cells from other lymphoid organs over this time period. Suspensions from lymph nodes were more strongly activated by PHA than were suspensions from spleen. Suspensions from the thymus either failed to be activated or were only weakly activated. The results indicate that the widely reported failure of the majority of thymus lymphocytes to be transformed by PHA reflects a failure of cell activation rather than of cell survival in vitro.