The effect of trauma on the structural-temporal organization of the T-dependent zone of a regional lymph node]

Experiments in 238 white mice have shown that after trauma there was a change in the population density (PD) of immune competent cells in the T-dependent zone of the regional lymph node (LN) both in the center of the deep cortex and in the T-territory adjacent to the germinative center. PD of small lymphocytes increases on the 1st-3rd days after trauma and returns to the initial level by the 4th-5th day. PD of mitotically dividing cells, immunoblasts, plasmablasts, immature and mature plasmocytes dramatically decreased on the 3rd day while an inconsiderable elevation of their PD took place on the 1st day in T-territory. The increased PD of small lymphocytes in the regional LN seems to be associated with their intensified release from the injury focus. The suppressed proliferation and differentiation of the plasmocyte line cells is the reaction to operation stress: in the posttraumatic period the spectral composition of fluctuations of PD of cells and parameters of its rhythmical components (both in the center of the deep cortex and in T-territory) were changed. As a rule, there was a displacement of acrophase and lessening of the rhythm amplitude. The general potency of the process after trauma increased. The amount of circadian components in the spectral composition of rhythmicity and their potency increased which speaks of central hormonal influences becoming greater.     

Spatial-temporal organization of the deep cortex of the lymph node

In various areas of the deep cortex: central and peripheral parts, as well as T-territory (adjoining the fundus of the germinative center) various cells (small and middle lymphocytes, immunoblasts, plasmoblasts, immature and mature plasma cells and mitotically dividing cells) have been counted. The population density of various immunocompetent cells differs significantly in various areas of the deep cortex. Immunoblasts predominate in the center, cells of the plasmic line--in the periphery of the deep cortex and in the T-territory. Fluctuations of the population density are time-dependent. Spectral composition and parameters of rhythmicity for each cellular type and general course of the process are estimated. In the spectral composition ultradian components predominate. The circadian components are more specific for T- than for B-dependent zone. For immunoblasts in all the zones a common period of fluctuations, nearly 10 h, is revealed, and for the cells of the plasmic line 7 hours' period is common; therefore, it is possible to suppose presence of synchronizing pace-makers of the rhythm for T-lymphocytes, on the one hand, and for antibody-forming cells, on the other hand. Spectral composition of rhythmicity of the cells in the T-territory and in other part of the deep cortex has a number of similar components, that demonstrates functional unity of these zones. A higher part of the cells of the plasmic line in the T-territory and in the periphery of the deep cortex is, perhaps, connected with their migration along these areas towards medullar cords. The general process is of a complex character, rises and drops are registered at various time of the day.     

Features of the structure of the regional lymph nodes of the duodenum in monkeys

By means of morphometric methods, duodenal regional lymph nodes were studied in rhesus and lapunder macaques. It was demonstrated that in monkeys the connective tissue framework, cortical plateau, medullary substance, cortical substance, sinuses and follicles are expressed differently. Cellular elements in the lymph nodes analysed in the monkeys subjected to a comparative investigation demonstrated their uneven distribution in the same structural components. Small lymphocytes were predominate cellular elements. There were rather essential differences in the number of plasmic cells, mitotically dividing cells, acidophilic granulocytes, mast cells and macrophages. Certain species differences were demonstrated to exist both in structure and cell composition of the lymph nodes that seemed to depend on some local peculiarities of immunogenic reactions.     

The thymus in exposure to pain

The effect of isotonic solution and microtrauma of the gastrocnemius muscle to the structure and cell composition in various zones of the thymus has been studied on mature white male rats on the first, 7th and 14th days of the experiment. At injection of the isotonic solution (sodium chloride) the part of small lymphocytes decreases and that of the large and middle ones--increases (it is mostly manifested on the 7th day of the experiment). The amount of immature plasma cells increases sharply at the same time, and that of mature cells--fluctuates during the experiment. The number of the mitotically dividing cells decreases. To some extent grows the part of the reticuloepitheliocytes; this demonstrates that migration of the lymphoid line cells from the thymus becomes greater. Pricks of the syringe needle do not produce any statistically significant changes.     

Changes in the lymphoid tissue and in the level of corticosteroids in staphylococcal intoxication and infection]

A complex quantitative study of changes of proliferative processes in lymphatic vessels on the one hand and changes of the level of corticosteroids in the peripheral blood in staphylococcal intoxication and infection in the same rats on the other hand has been carried out. In the work H3-thymidine has been used. The comparison of the obtained morphological data with the dynamics of the change in the corticosteroid level shows that the decay of lymphocytes, the devastating of light centers and the cortical substance of lymph nodes, an abrupt lowering of the amount of DNA-synthesizing and mitotically dividing cells take place in the period associated with a release of a great amount of corticosteroids into the blood. The drop of their level to control values goes in parallel with increasing the amount of DNA-synthesizing and mitotically dividing cells. The obtained data suggest that the leading role in those changes of the lympoid tissue which had been described by a number of authors in infectional processes is played by corticosteroids.     

Three-dimensional ultrastructural and immunohistochemical study of immature neurons in the subgranular zone of the rat dentate gyrus

The present study is devoted to three-dimensional ultrastructural organization of mitotically dividing immature neurons in dentate gyrus using biophysical approaches. In adult vertebrate brain, cell proliferation persists throughout life mainly in dentate gyrus of the hippocampus (DG) and olfactory bulb. Neurogenesis has been demonstrated using tagged thymidine analogues incorporated into the S phase of the cell cycle, but these may also detect repaired DNA in postmitotic neurons. Recent retroviral labelling has shown that neuronal progenitors/neuroblasts divide and produce functional neurons. Providing ultrastructural evidence of mitotically active cells has proven problematical, not only because of technical issues of identifying dividing cells at electron microscope level, but also because it is difficult to demonstrate unequivocally that neurons identified in the electron microscope are really post mitotic. However by characterising post mitotic cells labelled with BrdU and doublecortin and comparing these with post mitotic cells reconstructed in 3-dimensions from ultrathin serial sections, we have been able to illustrate individual mitotic elements and phases of cells within the GC layer of adult rat dentate gyrus. Here we show dividing cells in metaphase within clusters of immature GCs in subgranular zone (SGZ). These reconstructions provide ultrastructural confirmation that cells expressing doublecortin (DCX), a microtubule-associated protein expressed in migrating neurons, localize as clusters in the subgranular zone (SGZ) of dentate gyrus (DG) in the hippocampus during all animal life. Such DG cells with clear synaptic specializations, somatic spines and basal dendrites are exclusive to immature GC that appear to re-enter the cell cycle, suggesting the possibility that newly generated neurons within the DG might arise not only from precursors, but also from clusters of immature GC.     

Functional morphology of the lymphatic system of the rat uterus during pregnancy

In the regional lymph nodes of the uterus the comparative volume of the paracortical zone significantly increases, especially within the period of the 13th-17th days of pregnancy. In the popliteal lymph node similar effect is not discovered. From the 7th up to the 11th day edema, vasodilatation, infiltration with special leucocytes are revealed. Endothelium of the postcapillary venules is hypertrophied, contains many migrating lymphocytes, which accumulate around the vessels mentioned. The volume of the microcirculatory bed is moderately increased. By the 17th day plasmoblasts, plasmocytes, Motta's cells, monocytes and especially macrophages appear in the paracortical zone. In B-zones and in medullary sinuses blasts, plasma cells, monocytes, macrophages, mitotically deviding cells increase in number. The part of the reticular cells decreases. The tensometric method demonstrates an increasing pressure of lymph in the iliac lymph node at pregnancy. Collateralies appear in the ovarian vein system, in the broad ligament of the uterus, in the lumbar area. The uterine vascular system is supposed to participate in adaptation to pregnancy. In genesis of the regional lymph node changes, discirculatory shifts, predominating during placental organogenesis, combine with phenomena of cell migration and proliferation (clearly revealed by the time when formation of the placenta is completed).     

Cellular composition of various structural zones of the iliac and mesenteric lymph node of pregnant rats

The dynamic of cellular reactions demonstrates certain changes in functional activity of all structures of the node during pregnancy. A similar trend of processes in the iliac (regional for the uterus) and mesenteric lymph nodes has been defined. At early stages of pregnancy, lymph nodule are the most active, this is demonstrated as an increasing portion of lymphoblasts, macrophages and dividing cells. During this period, cell composition of the cortical plateau is relatively stable. For the paracortical zone of the mesenteric lymph nodes a rather significant decrease in the portion of middle lymphocytes and reticular cells is characteristic. There is not any significant change in the relative amount of the cells in the same functional zone of the iliac lymph nodes during the same period of pregnancy. The medullar cords demonstrate an increasing number of blast forms and young plasmocytes. However, as the pregnancy develops, the structure of the paracortical zone undergoes an essential change--progressively increases the portion of lymphoblasts and large lymphocytes. The blastic reaction in the mesenteric lymph nodes is proved to depend, to some extent, on that in the iliac lymph nodes of the same animal. Mature plasma cells become the dominating cellular element in the medullary cords. At the end of the pregnancy a relative amount of the reticular cells increases in all structural zones of the node.     

Biological rhythms of cells of the lymphoid series in the thymus-dependent zone of lymph nodes

Biological rhythms of density in the lymphoid line cell populations (small and middle lymphocytes, immunoblasts, plasmoblasts, immature and mature plasmocytes) have been investigated in the thymus-dependent zone of the mouse axillary lymph nodes. The observations have been performed for 572 h. The amount of the cells is counted over the nodes of the morphometrical net. The results of the observations are treated by means of the spectral cosinor-analysis. Circadian or similar to it rhythmicity is peculiar for all the types of the cells, besides plasmoblasts. Within the ultradian range rhythmicity of the small lymphocytes, immunoblasts and immature plasmocytes is presented by two components, and that of the plasmoblasts--by one. The complexity of the rhythm components demonstrates that the course of the process during the observation time does not repeat strictly every day running, since periods of the circadian components somewhat fluctuate from 24 h, and periods of the ultracircadian ones--do not make multiple parts from the duration of the circadian periods. The time of picks and troughs of the amount of the cells during successive 24 h also do not coincide with each other, as the circadian and ultradian components interact. During one 24-hour's period the curve does not possess a regular sinusoid form and additional picks and troughs are revealed, since certain oscillations of a higher frequency participate in the process. These data are necessary to estimate reactions at T-immunological response.     

Cellular composition of structural components of the lymph nodes of rats during rehabilitation after dimethyl sulfate poisoning

By means of microanatomical methods the inferior tracheobronchial lymph nodes have been investigated in 48 Wistar rats in 2 weeks and 3 months after discontinuance of inhalation of dimethylsulfate (DMS) vapours for 2 and 14 days by the animals in concentration 2.0 mg/m3, that is to say during rehabilitation period. Comparison of relative parameters of the structural components areas and cell composition of the lymph nodes has been carried out. During rehabilitation period after DMS inhalation for 2 days the cortical and medullary areas in histological preparations do not essentially differ from corresponding parameters of an acute experiment (2 days, 2.0 mg/m3, without rehabilitation). Amount (%) of cells with mitotic figures in the lymphoid nodules++ increases in 2 weeks and in 3 months. Contents of poorly differentiated cells during rehabilitation periods increase in the cortical plateau, but keeps nearly at the same low level as during the acute experiment in the lymphoid nodules++. In 2 weeks after DMS influence for 14 days, the cortical and medullary area in the histological preparations reach the control levels. In the lymphoid nodules++ a relative amount of reticular, poorly differentiated, mitotically dividing cells increases, and in the medullary cords contents of middle and small lymphocytes become greater in comparison with the acute experiment (14 days, 2.0 mg/m3, without rehabilitation).(ABSTRACT TRUNCATED AT 250 WORDS)     

Morpho-functional status of the lymph nodes of rats during rehabilitation after exposure to vapors of dimethyl sulfate]

By means of histological methods inferior tracheobronchial lymph nodes have been investigated in 48 Wistar rats in 2 weeks and 3 months after cessation of inhalation of DNSV at maximum possible dose (0.1 mg/m3) for 2 and 14 days. Cell composition of the lymph nodes and cross sections of structural components have been compared. The cross section of the cortex decreases, while that of the medulla increases in comparison with corresponding parameters of the acute experiment. In 2 weeks and 3 months after DMSV effect for 2 days the part (%) of poorly differentiated cells and middle lymphocytes increases, while content of plasma cells in the medullary cords decreases. During rehabilitation after DMSV effect for 14 days a low level plateau is noted (as in the acute experiment). However, in lymphoid nodules++ within content of the poorly differentiated cells and middle lymphocytes in the cortical germinative centers in 2 weeks and 3 months the number of the poorly differentiated and reticular cells increases essentially, as well as mitotically dividing cells (in comparison to the acute experiment). In the medullary cords of the lymph nodes after 3 months of rehabilitation content of immature plasma cells is essentially higher than in 2 weeks of rehabilitation and than in the acute experiment. During rehabilitation the level of cells destruction in the lymph nodes noticeably decreases in comparison to the acute experiment.     

Seasonal changes in recovery of cryopreserved murine lymphocytes resemble endogenous rhythms of unfrozen cells

Seasonal changes in the resistance of C57BL/6 mouse splenocytes to cryopreservation stress were expressed in both the recovery of viable cells and the levels of responses of T and B lymphocytes to mitogens in vitro. Single cell suspensions in 10% Me2SO were cooled at 1 degree C/min, the optimum velocity which was determined by using a range of cooling rates during January and May, the months of minimum and maximum recoveries of viable cells, respectively. After rapid thawing and washing, ethidium bromide-fluorescein diacetate staining delineated viable and nonviable cells. Cultures containing 0.5 X 10(6) viable cells were stimulated with the T lymphocyte mitogens, phytohemagglutinin and concanavalin A, and the B lymphocyte mitogen, lipopolysaccharide. Tritiated thymidine was added to each culture for the last 18 hr of the incubation period, and its incorporation by activated dividing cells was determined. Recoveries of viable cells were high from March through July and then declined to minimum levels in January and February. During the seasons of low recoveries, greater numbers of cells lysed in response to the freeze-thaw cycle. Activation of both T and B lymphocytes by mitogens was maximal in the spring and summer and then declined to only 40% of unfrozen control levels in October. The patterns of activation resembled those of the previously documented endogenous seasonal rhythms in levels of blastogenesis of unfrozen cells. These seasonal differences in cryopreservation properties of lymphocytes from inbred mice living under constant conditions reinforce the previously reported endogenous annual rhythmicity in cellular functions.     

Acute SIV Infection in Sooty Mangabey Monkeys Is Characterized by Rapid Virus Clearance from Lymph Nodes and Absence of Productive Infection in Germinal Centers

Lymphoid tissue immunopathology is a characteristic feature of chronic HIV/SIV infection in AIDS-susceptible species, but is absent in SIV-infected natural hosts. To investigate factors contributing to this difference, we compared germinal center development and SIV RNA distribution in peripheral lymph nodes during primary SIV infection of the natural host sooty mangabey and the non-natural host pig-tailed macaque. Although SIV-infected cells were detected in the lymph node of both species at two weeks post infection, they were confined to the lymph node paracortex in immune-competent mangabeys but were seen in both the paracortex and the germinal center of SIV-infected macaques. By six weeks post infection, SIV-infected cells were no longer detected in the lymph node of sooty mangabeys. The difference in localization and rate of disappearance of SIV-infected cells between the two species was associated with trapping of cell-free virus on follicular dendritic cells and higher numbers of germinal center CD4⁺ T lymphocytes in macaques post SIV infection. Our data suggests that fundamental differences in the germinal center microenvironment prevent productive SIV infection within the lymph node germinal centers of natural hosts contributing to sustained immune competency.     

rC5a directs the in vitro migration of human memory and naive tonsillar B lymphocytes: implications for B cell trafficking in secondary lymphoid tissues.

Human C5a is a potent chemoattractant for granulocytes, monocytes, and dendritic cells. In mice C5a has been shown to be chemotactic for germinal center (GC) B cells. To date, no information is available on the effects of C5a on human B cell locomotion. Here we demonstrate that rC5a increases polarization and migration of human tonsillar B cells. The locomotory response was due to both chemokinetic and chemotactic activities of rC5a. Moreover, memory and, at a lesser extent, naive B cell fractions from purified tonsillar populations displayed rC5a-enhanced migratory properties, whereas GC cells did not. Flow cytometry revealed C5aR (CD88) on approximately 40% memory and 10% naive cells, respectively, whereas GC cells were negative. Immunohistochemistry showed that a few CD88+ cells were of the B cell lineage and localized in tonsillar subepithelial areas, where the majority of memory B cells settle. Pretreatment of memory B cells with the CD88 mAb abolished their migratory responsiveness to rC5a. Finally, the C5 gene was found to be expressed in naive, GC, and memory B lymphocytes at both the mRNA and the protein level. This study delineates a novel role for C5a as a regulator of the trafficking of human memory and naive B lymphocytes and supports the hypothesis that the B cells themselves may serve as source of C5 in secondary lymphoid tissues.     

The temporal organization of the complex nodule in the lymph node

The aim of the work is to study rhythmic processes at tissue level in the lymph nodule and in the T-territory adjacent to it in order to reveal temporal interrelations in functioning the germinative center, crown and T-territory. The lymph nodule sections are stained with methylene green-pyronine. Small and middle lymphocytes, immunoblasts, plasmoblasts, immature and mature plasma cells, mitotic figures are taken into account. Spectral composition and rhythmic parameters are determined for each type of the cells in the ultradian, circadian and infradian ranges. Periods, approaching the circadian one, are revealed in the germinative centers for small lymphocytes and immature plasma cells. Practically, for all plasma cells the functional period near to 7 h is found; this attests the presence of the common synchronous rhythm driver. Phase difference of immunoblast, plasmablast, immature plasma cell fluctuation in the germinative centers makes it possible to suppose the time, necessary to transfer the immunoblast into the plasmablast (1.6-2.6 h) and the plasmablast into the immature plasma cell (3 h). Owing to the knowledge of the spectral composition of the rhythmic and parameters of certain components it is possible to approximate the total course of the process. Combination of fluctuations with various periods results in their recurrence in more prolonged time intervals.     

Requirement for non T-cells in the generation of cytotoxic T lymphocytes (CTL) in vitro. II. Characterization of the active cells in the spleen of nude mice.

Small numbers of LN cells will produce many more cytotoxic lymphocytes on in vitro culture with allogeneic stimulator cells if spleen cells from nu/nu mice are also present throughout the culture period. All cytotoxic cells produced are T cells and arise from precursors in the LN component. The nude spleen component appears to be providing a required non-T cell which has been lost from the LN component through dilution. At least two active subpopulations of cells, differing in sedimentation velocity, adherence properties, radiation sensitivity, and antigen recognition properties can be identified in the nu/nu spleen. The first, the dominant activity in normal nu/nu spleen, is nonadherent, radiation sensitive, and can synergize with either syngeneic or allogeneic LN cells provided both are different from the same alloantigens in the stimulator population. The second, found in nu/nu spleen cells precultured with alloantigen, sediments more rapidly, is adherent, and radiation resistant, and need not be allogeneic to the stimulator cells to synergize with LN cells. The first subpopulation may give rise to the second.     

Rhesus Macaque Lymph Node PD-1hiCD4+ T Cells Express High Levels of CXCR5 and IL-21 and Display a CCR7loICOS+Bcl6+ T-Follicular Helper (Tfh) Cell Phenotype

CD4 T follicular helper (Tfh) cells play a unique and essential role in the generation of B cell responses in the lymph node microenvironment. Here we sought to determine if differential expression of PD-1 could be used to delineate Tfh cells in rhesus macaque lymph nodes (LN). CD3⁺CD4⁺ T cells were found to harbor a unique subset of cells that expressed the Program death-1 (PD-1) receptor at significantly high levels that were enriched in the LN compartment as compared to peripheral blood. The LN CD4⁺PD1^hi T cells expressed a predominantly CD28⁺CD95⁺ central memory phenotype and were CCR7^loICOS^hiBcl6^hi. Additionally, CD4⁺PD1^hi T cells preferentially expressed high levels of CXCR5 and IL-21 and significantly correlated with Bcl6⁺Ki-67⁺ IgG⁺ B cells. As Bcl6 is primarily expressed by proliferating B cells within active germinal centers, our results suggest that LN CD4⁺PD1^hi T cells likely localize to active GC regions, a characteristic that is attributable to Tfh cells. Overall, our findings suggest that high levels of PD-1 expression on CD4⁺ T cells in LN of rhesus macaques can serve as a valuable marker to identify Tfh cells and has implications for studying the role of Tfh cells in Human immunodeficiency virus (HIV), Simian immunodeficiency virus (SIV) and other infectious diseases that use the rhesus macaque model.     

Analysis of the spatial expression pattern of seven Kip related proteins (KRPs) in the shoot apex of Arabidopsis thaliana

BACKGROUND AND AIMS: Kip-related-proteins (KRPs), negative regulators of cell division, have recently been discovered in plants but their in planta function is as yet unclear. In this study the spatial expression of all seven KRP genes in shoot apices of Arabidopsis thaliana were compared. METHODS: In situ hybridization analyses were performed on longitudinal sections of shoot apices from 2-month-old Arabidopsis plants. KEY RESULTS: The study provides evidence for different expression pattern groups. KRP1 and KRP2 expression is restricted to the endoreduplicating tissues. In contrast, KRP4 and KRP5 expression is mainly restricted to mitotically dividing cells. KRP3, KRP6 and KRP7 can be found in both mitotically dividing and endoreduplicating cells. CONCLUSION: The results suggest differential roles for the distinct KRPs. KRP1 and KRP2 might specifically be involved in the establishment of polyploidy. In contrast, KRP4 and KRP5 might be involved in regulating the progression through the mitotic cell cycle. KRP3, KRP6 and KRP7 might have a function in both types of cell cycle.