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The splenic lymphoid tissue of mice reared in a conventional environment regressed with increasing age. Immunogloblin G positive plasma cells gathered along the penicilli in the senile spleen as well as in the adult control spleen. The number of plasma cells around the penicilli showed no difference in the senile spleen as compared to the adult spleen. Since mature plasma cells remain in the lymph node for a short time only and seldom divide there, our results indicate that the transformation from B lymphocyte to plasma cell is not affected by age. 相似文献
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M Honda T Yoshimura T Watanabe H Hayashi 《Journal of immunology (Baltimore, Md. : 1950)》1983,131(6):2989-2994
The chemotactic specificity of ia-positive and -negative macrophages was studied by using three macrophage chemotactic factors (MCF), -a, -b, and -c, isolated from delayed hypersensitivity reaction (DHR) skin sites in guinea pigs. Listeria-elicited macrophages migrated toward MCF-a, -b, and -c. The chemotactic responses suggested responsive subpopulations to MCF. The electronic programmable individual cell sorter (EPICS) was used to separate macrophages with anti-la monoclonal antibodies. Ia-positive subpopulations responded to MCF-c, although they did not migrate toward MCF-a and -b. In contrast, Ia-negative subpopulations migrated toward MCF-a and -b, but not toward MCF-c. Furthermore, MCF-c attracted Ia-positive macrophages, whereas MCF-a and -b were Ia-negative in vitro; MCF did not induce Ia-negative macrophages to express surface Ia-antigens in vitro. MCF-c was able to produce massive Ia-positive macrophage accumulations when injected i.p., whereas MCF-a accumulated Ia-negative macrophages. The data suggest that MCF-a and -b, which mediate initial macrophage reactions, attract Ia-negative macrophages, and that MCF-c, which mediates predominant macrophage reactions, attract Ia-positive macrophages in the DHR. 相似文献
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To investigate the mechanisms that regulate the action of interleukin 2 (IL 2) and possibly limit its activity, we screened supernatants of mouse spleen cell cultures which had been stimulated with concanavalin A (Con A) for their ability to inhibit IL 2-mediated proliferation of a cloned IL 2-dependent line. Inhibitory activities with m.w. of 10,000 to 12,000 and 60,000 to 80,000 daltons could be identified in supernatants of both L3T4+ and Ly-2+ T cells, but not in supernatants of Con A or lipopolysaccharide-stimulated B cells. Maximal inhibitory activity was observed after 3 to 4 days of stimulation, and this inhibitory activity could be overcome by increasing the stimulatory concentration of IL 2. When the factor was further purified by reverse-phase high pressure liquid chromatography, it eluted as a single peak with an m.w. of 11,000 to 12,000 daltons which inhibited IL 2- but not IL 3-dependent proliferation. The mechanisms by which this new lymphokine might play in the control of the clonal expansion of T lymphocytes are discussed. 相似文献
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The organization of the ribosomal RNA genes was examined in several species of Vicia in an attempt to determine whether a relationship exists between genome size and ribosomal repeat length. Species within this genus exhibit a sevenfold variation in haploid DNA content. Our data suggest that species with an intermediate genome size maintain one predominant Eco RI class of ribosomal repeat of about 9 kilobases (kb). In contrast, the smallest and largest genomes of Vicia possess one major and several minor classes. The possible relationship between repeat classes among species is discussed. We examined the species with the smallest (V. villosa) and largest (V. faba) genomes in closer detail by R-loop analysis of a satellite DNA from Hoechst 33258 dye-CsCl gradients. Heterogeneity was found in the length of the ribosomal repeat for both species, but no appreciable difference was observed in the distribution of these lengths, which averaged 11–12 kb. This heterogeneity is associated with the nontranscribed spacer region. Intervening sequences were not found in either the 25S or 18S coding regions of the ribosomal repeat of either of these two plants. A putative ribosomal RNA precursor of 7 kb was identified for both species. 相似文献
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Nitrite, a stable metabolite of nitric oxide (NO), is measured fluorometrically as an indicator of NO production using 2,3-diaminonaphthalene. In cultured cells, it has been believed that a longer period of incubation improves the detection sensitivity because of the accumulation of nitrite formed from NO in culture media. However, here we show that nitrite formed from nitrogen oxide air pollutants accumulates continuously in culture media during the incubation and interferes with the measurement of NO as nitrite. Thus, a proper period of incubation is important to allow maximum nitrite signals from NO with minimum background nitrite from the air. 相似文献
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