Development of specific antibody-forming cells in various lymphoid organs of rabbit after intravenous antigen administration

Rabbits were intravenously primed and boosted with trinitrophenyl-keyhole limpet hemocyanin (TNP-KLH) and human serum albumin (HSA); both antigens were injected simultaneously. The localization of anti-TNP-antibody-forming cells (AFCs) and anti-HSA-AFCs was determined in various lymphoid organs of the rabbit. In all lymphoid organs of primed rabbits anti-TNP-AFCs outnumbered anti-HSA-AFCs, with the exception of the thymus, in which neither of them was encountered. In the spleen the antibody-forming cells were mainly situated in the periphery of the periarteriolar lymphocyte sheaths (PALS) and in the coaxial sheaths of lymphoid tissue surrounding the terminal arterioles. In the lymphoepithelial organs AFCs were almost exclusively situated in the interfollicular areas, and in the lymph nodes largely in the medulla. An intravenous booster injection led to a secondary immune response (i.e., increase of AFCs) in the spleen. No visible change in the number of specific AFCs was observed in the lymphoepithelial organs. However, in the mesenteric and popliteal lymph node the number of anti-TNP-AFCs had increased tremendously.     

The long-term distribution of antibody-forming cells

Previous experiments suggested that the spleen might not be the chief source of serum antibody synthesized several months after the immunization of mice by sheep erythrocytes; this has been confirmed for classes other than γM. The anatomical location of the cells making the antibody is not the same for each class. The thymus contains a relatively greater number of non-γM antibody-producing cells late in the response than it does in the first three weeks after immunization.     

Innate lymphoid cells in secondary lymphoid organs

The family of innate lymphoid cells (ILCs) has attracted attention in recent years as its members are important regulators of immunity, while they can also cause pathology. In both mouse and man, ILCs were initially discovered in developing lymph nodes as lymphoid tissue inducer (LTi) cells. These cells form the prototypic members of the ILC family and play a central role in the formation of secondary lymphoid organs (SLOs). In the absence of LTi cells, lymph nodes (LN) and Peyer's Patches (PP) fail to form in mice, although the splenic white pulp can develop normally. Besides LTi cells, the ILC family encompasses helper-like ILCs with functional distinctions as seen by T-helper cells, as well as cytotoxic natural killer (NK) cells. ILCs are still present in adult SLOs where they have been shown to play a role in lymphoid tissue regeneration. Furthermore, ILCs were implicated to interact with adaptive lymphocytes and influence the adaptive immune response. Here, we review the recent literature on the role of ILCs in secondary lymphoid tissue from the formation of SLOs to mature SLOs in adults, during homeostasis and pathology.     

The role of the lymphoid organs in antibody production

Summary Simultaneous removal of the thymus gland and spleen in rabbits does not affect the viability of these animals. Together with the other organs the thymus gland and the spleentake part in the response of the animal to the administration of the typhoid antigen. This participation is manifested in various forms: thymectomy promotes greater accumulation of the antibodies in the blood; splenectomy on the contrary reduces the titre: Simultaneous removal of the thymus and spleen results in a greater accumulation of antibodies than in the case of splenectomized animals, although it is slightly less than in the normal ones.Thus one may assume that the thymus has a depressing effect on the mechanisms responsible for the accumulation of the antibodies in the blood; this effect is especially clearly manifested in the absence of the spleen. This is also confirmed experimentally by the increased titer of circulating antibodies in splenectomized rabbits after thymectomy, as well as by experiments with administration of thymus homogenate. The depressive effect of the thymus gland is manifested only during the first 48 hours after the administration of the antigen.From the Division of Infectious Pathology and Experimental Therapy of Infections (Head-Corresponding Member AMN SSSR Kh. Kh. Planel'es) of the N. F. Gamaleya Institute of Epidemiology and Microbiology (Director-Prof. S. N. Muromtsev)Presented by Active Member AMN SSSR L. A. Zil'ber     

Ontogeny of primary lymphoid organs and lymphoid stem cells

Cells of the immune system go through a series of important developmental steps that begin early in embryonic life and include, first, the various waves of hemopoietic-cell production in the embryo and, second, the homing of these cells to the hemopoietic organs, which are the sites of hemopoiesis and lymphopoiesis in embryonic and adult life. The avian embryo is an important model for investigating these early steps; and this paper presents a comprehensive review of the work done on the early ontogeny of the avian immune system.     

The appearance of non-specific antibody-forming cells in the efferent lymph draining antigen-stimulated single lymph nodes.

Immunization of single lymph nodes with various antigens led to the appearance of cells in the efferent lymph that secreted antibody specific for the antigen which induced their formation and for a number of unrelated, non-crossreacting antigens. Immunization of single lymph nodes with mitogens led to the appearance of cells secreting antibodies specific for an even greater number of antigens, including one (TNP) that in all probability is not present in the animals' natural environment. When the node was primed with one antigen, a subsequent challenge with an unrelated antigen 12 weeks later led to the appearance of greater numbers of cells containing and secreting antibody against the previously experienced antigen, than was the case in unprimed lymph nodes. These findings indicate that the immune response to antigen provokes the maturation of lymphocytes of specificities unrelated to that of the injected immunogen. Such a mechanism may be important in maintaining immunological memory. Mitogens may directly activate lymphocytes into maturation and expression as antibody-secreting cells, whereas antigens appear to act indirectly.     

Immunoglobulin-containing cells in different lymphoid organs of the CBA mouse during its life-span.

The number of cells containing cytoplasmic immunoglobulin (C-Ig cells) was determined in the spleen, mesenteric lymph nodes, bone marrow and Peyer''s patches of CBA mice of different ages. A rapid increase in the number of C-Ig cells at between 2 and 6 weeks of age was observed in spleen and gut-associated lymphoid organs. The absolute number of C-Ig cells in these organs decreases with advancing age. In the bone marrow, the number of C-Ig cells increases steadily with age up to one year. From one year on, the number remains approximately constant in the males. In female mice, the number of C-Ig cells, mainly of the IgA class, increases sharply around 1 year of age. The spleen is the major site of Ig synthesis up to about 6 months of age. In older animals, the relative contribution of the bone marrow increases with age, possibly due to a gradual shift in the individual animal from primary type responses to a pattern of secondary type responses. No indication of a decreased overall immunological activity in senescence was obtained.     

Dendritic cells in the T-cell areas of lymphoid organs

Summary: Substantial numbers of dendritic cells (DCs) are found in the T-cell areas of peripheral lymphoid organs such as the spleen, lymph node and Peyer's patch. By electron microscopy these DCs (also called interdigitating cells) form a network through which T cells continually recirculate. The cytological features of DCs in the T-cell areas, as well as a number of markers detected with monoclonal antibodies, are similar to mature DCs that develop from other sites such as skin and bone marrow. Some markers that are expressed in abundance are: MHC II and the associated invariant chain, accessory molecules such as CD40 and CD86, a multilectin receptor for antigen presentation called DEC-205, the integrin CD11c, several antigens within the endocytic system that are detected by monoclonal anti-bodies but are as yet uncharacterized at the molecular level, and, in the human system, molecules termed Sl00b, CD83 and p55. DCs in the periphery can pick up antigens and migrate to the T-cell areas to initiate immunity However, there are new observations that DCs within the T-cell areas also express high levels of self-antigens and functional fas-ligand capable of Inducing CD4⁺ T-cell death. We speculate that there are at least 2 sets of DCs in the T-cell areas, a migratory myeloid pathway that brings in antigens from the periphery and induces immunity, and a more resident lymphoid pathway that presents self-antigens and maintains tolerance.     

Clones of antibody-forming cells in pokeweed mitogen-stimulated microcultures. I. Requirements for the induction of the antibody response of nude spleen cells

The effect of pokeweed mitogen (PWM) on the activation of precursor cells specific for sheep red cells (SRC) was studied in the microculture system. It was found that:

• 1 (a) PWM does not augment the response of nude spleen cells in the absence of T cells.
• 1 (b) When microcultures of nude spleen cells are supplemented with irradiated allogeneic spleen cells, the addition of PWM increases the number of precursor cells engaged in the anti-SRC response.
• 1 (c) Allogeneic supernatant produced in the presence of PWM is more active than that produced in the absence of PWM.

     

Precursor cell division during the immune response in vitro: antigen-induced and "spontaneous" antibody-forming cells

“Background” or “spontaneous” plaque-forming cells (PFC) which arise during in vitro culture of mouse spleen cells may be eliminated by a hot thymidine pulse. This does not prevent the subsequent addition of sheep red blood cells (SRBC) or trinitrophenylated (TNP) SRBC eliciting a primary immune response. Using mouse spleen cells, resently primed by carrier (SRBC), it was found that an early “hot pulse” (for the first 24 hours of culture) can eliminate the anti-SRBC response, but not the primary anti-TNP response which is dependent on carrier-specific, θ-bearing, radioresistant spleen cells.     

Detection of antibody-forming cells and humoral antibody to horseradish peroxidase.

Two new simple methods for detecting antibody-forming cells by hemolytic plaque assay and hemagglutinating antibody to horseradish peroxidase have been developed in mice. Both techniques utilize as target, sheep erythrocytes coupled directly with horseradish peroxidase. These assays are sensitive, antigen-specific and are useful to quantitate both direct and indirect antibody-forming cells and humoral antibodies.     

Target cells for duck enteritis virus in lymphoid organs

Duck enteritis virus (DEV), a herpesvirus, has been shown to cause lymphoid organ atrophy and immunosuppression in white Pekin ducklings. The cells that support virus replication and could be important for immunosuppression were identified in this study. Lymphoid organs of white Pekin ducks infected at 2 weeks of age were collected at 3, 6, 8 and 10 days post-inoculation (d.p.i.). Frozen sections were double-stained for DEV-infected (DEV+) and epithelial cells, DEV+ and CD3+ cells or DEV+ and B cells. DEV antigen was detected in the spleen, thymus and bursa for 3, 6 and 8 d.p.i., respectively. DEV antigen was demonstrated in epithelial cells of all examined lymphoid organs. B cells were irreversibly depleted from bursa; however, the depletion in the spleen was only for 8 d.p.i. Depletion of CD3+ cells was only observed in the thymus. These data show that the target cells for DEV are epithelial and B cells.     

Origin of dendritic cells in peripheral lymphoid organs of mice

Parabiosis experiments demonstrating that dendritic cells (DCs) do not equilibrate between mice even after prolonged joining by parabiosis have suggested that DCs are derived from self-renewing progenitors that divide in situ. However, here we found that unequal exchange of DCs between mice joined by parabiosis reflected uneven distribution of DC precursors in blood due to their short half-life in circulation. DCs underwent only a limited number of divisions in the spleen or lymph nodes over a 10- to 14-day period and were replenished from blood-borne precursors at a rate of nearly 4,300 cells per hour. Daughter DCs presented antigens captured by their progenitors, suggesting that DC division in peripheral lymphoid organs can prolong the duration of antigen presentation in vivo.     

Obesity affects peripheral lymphoid organs immune response in murine asthma model

Asthma and obesity present rising incidence, and their concomitance is a reason for concern, as obese individuals are usually resistant to conventional asthma treatments and have more exacerbation episodes. Obesity affects several features in the lungs during asthma onset, shifting the T helper type 2 (Th2)/eosinophilic response towards a Th17/neutrophilic profile. Moreover, those individuals can present reduced atopy and delayed cytokine production. However, the impact of obesity on follicular helper T (Tfh) cells and B cells that could potentially result in antibody production disturbances are still unclear. Therefore, we aimed to assess the peripheral response to ovalbumin (OVA) in a concomitant model of obesity and asthma. Pulmonary allergy was induced, in both lean and obese female BALB/c mice, through OVA sensitizations and challenges. Mediastinal lymph nodes (MLNs) and spleen were processed for immunophenotyping. Lung was used for standard allergy analysis. Obese-allergic mice produced less anti-OVA IgE and more IgG2a than lean-allergic mice. Dendritic cells (CD11c⁺ MHCII^high) expressed less CD86 and more PDL1 in obese-allergic mice compared with lean-allergic mice, in the MLNs. Meanwhile, B cells (CD19⁺ CD40⁺) were more frequent and the amount of PDL1/PD1⁺ cells was diminished by obesity, with the opposite effects in the spleen. Tfh cells (CD3⁺ CD4⁺ CXCR5⁺ PD1⁺) expressing FoxP3 were more frequent in obese mice, associated with the predominance of Th (CD3⁺ CD4⁺) cells expressing interleukin-4/GATA3 in the MLNs and interleukin-17A/RORγT in the spleen. Those modifications to the main components of the germinal centers could be resulting in the increased IgG2a production, which – associated with the Th17/neutrophilic profile – contributes to asthma worsening and represents an important target for future treatment strategies.     

The immune response in lymphoid organs of rat: A cytochemical study

Variations in the activity of lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), dihydrofolate reductase (DHFR) and alkaline phosphatase (ALP) were studied, using the light microscope (LM), and cytochemical reactions in lymphoid organs (lymph node, spleen, thymus) of rats, up to day 5 following Escherichia coli immunisation. Increased levels of LDH and DHFR in the T-area of lymph nodes and of spleen were seen from day 2 to day 4 postimmunisation. The SDH reaction in lymph nodes and in the spleen increased during days 2 and 3 but decreased on day 4 postimmunisation. Considerable increases in the activities of LDH and SDH were seen in thymus at all times postimmunisation. The DHFR reaction product also increased but less markedly. No reaction for ALP was observed in lymphocytes of lymphoid organs studied. Following E. coli immunisation, there is an increase in glycolytic and respiratory metabolism, and in the synthesis of proteins in T-dependent areas of lymphoid organs. These increases are correlated with immune activation of T-cells in these organs.     

The localization of haemolytic antibody in sections of lymphoid organs: an improved method

A simple and sensitive method is described for detecting foci of haemolysin-producing cells in tissues. Frozen sections are mounted on glass, covered with an agar—red cell gel and complement, incubated, fixed, stained and mounted. The preparation is examined in toto.

In the primary response to sheep red cells, antibody appears first in the red pulp and subsequently in germinal centres. This sequence is repeated in the secondary response, but is accelerated.

In cyclophosphamide-treated mice injected with sheep red cells and 10⁷ isogeneic spleen cells, about five to twenty haemolytic foci are seen per transverse spleen section.

     

Changes in immunological activity of rat lymphoid organs during pregnancy.

Immune reactivity in lymhoid organs of rats during the last week of syngeneic (Lewis: L x L) or allogeneic (females Lewis x males Wistar: L x W) pregnancy was compared with that found in non-pregnant animals. The thymus weight was slightly reduced and the response of thymic lymphocytes to phytohaemagglutinin and concanavalin A was slightly, but not significantly, elevated in pregnant rats. By contrast, the response of lymphoid cells from spleen and mesenteric lymph nodes to the mitogens was reduced in rats during advanced pregnancy. The immune response of lymphocytes from pregnant L x W rats to allogenic (Brown-Norway: BN) or semiallogeneic (W) irradiated cells was tested by the mixed lymphocyte culture (MLC) assay. The MLC response of para-aortic lymph nodes towards the unrelated BN cells was elevated over that of non-pregnant rats on day 15 of pregnancy. No significant enhancement was observed at the same time in the MLC response of mesenteric lymph nodes. On day 20 of pregnancy, a reduced MLC response towards BN cells was found in the mesenteric and para-aortic lymph nodes. On day 15 of pregnancy, the MLC response of mesenteric and, more markedly, that of para-aortic lymph nodes to paternal (W) cells was enhanced, as compared to that of non-pregnant rats. On day 20 of pregnancy, the response of mesenteric lymph nodes was suppressed, while the response of para-aortic lymph nodes was similar to that found in non-pregnant rats. Since the latter lymph nodes are the most directly exposed to antigenic stimulation from the uterus, it seems unlikely that the suppression in response to T-cell mitogens observed in the spleen and mesenteric lymph nodes during pregnancy accounts for the survival of the foetus. It seems more plausible that local factors in the vicinity of the uterus protect the foetus from being rejected.