The effects of antigen on the migration of recirculating lymphocytes through single lymph nodes

Mechanisms of human lymphocyte migration and their role in the pathogenesis of disease

Lymphocyte recirculation is an essential component of the functional immune system, providing a means for constant surveillance of the organism's tissues by immunocompetent cells and, moreover, facilitating interactions between different cell types engaged in the immune response. Adhesive interactions between recirculating lymphocytes and the wall of high endothelial venules (HEV) are thought to play a central role in this process. These interactions are mediated by lymphocyte homing receptors expressed on the lymphocyte cell surface which recognize tissue-specific molecules on the endothelium. Moreover, LFA-1 is also involved in the regulation of lymphocyte traffic. In addition, recent evidence indicating that these mechanisms may also play a role in the pathogenesis of chronic inflammatory diseases and non-Hodgkin's lymphomas is discussed.

Bovine peripheral blood leukocyte population dynamics following treatment with recombinant bovine interferon-alpha I1

The in vitro functional activity of bovine peripheral blood lymphocytes and the population dynamics of the major peripheral blood leukocyte subpopulations were investigated following the administration of recombinant bovine interferon-alpha I1 (rBoIFN-alpha I1). The intramuscular injection of rBoIFN-alpha I1 induced a 24-h lymphopenia characterized by a decrease in both circulating T and non-T/non-B lymphocytes. An increased CD4/CD8 ratio indicated that there was a relatively greater depletion of the CD8 equivalent subpopulation of T lymphocytes. These changes in lymphocyte trafficking were observed in the absence of a cortisolemia. Coincidental with the lymphopenia, there was a marked decrease in the amplitude of mitogen-induced lymphocyte proliferation responses that probably was caused by a numerical deficit rather than functional deficit in the responder T cells.

Antigen-specific regulation of T lymphocyte proliferative responses to contact-sensitizing chemicals in the guinea pig

Skin painting of guinea pigs with either 4-ethoxymethylene-2-phenyloxazol-5-one or 2,4-dinitrofluorobenzene induced not only a primary proliferative response in the draining lymph node but also the systemic suppression of subsequent proliferative responses to topically applied hapten. The inhibition of lymphocyte proliferation, as assessed by the incorporation of [3H]-thymidine and the presence of large pyroninophilic cells in the paracortex, was hapten-specific and long-lasting. This study demonstrates that, in common with the mouse, the sensitization of guinea pigs results in the induction of a hapten-specific suppressor mechanism, which serves to control the proliferative response following reexposure to hapten. However, the antigen-nonspecific suppression of proliferation observed in the mouse following exposure to some potent contact sensitizers was not, under the conditions employed, detectable in the guinea pig.

Recirculation of lymphocyte subsets (CD5+, CD4+, CD8+, SBU-T19+ and B cells) through gut and peripheral lymph nodes

The surface phenotypes (CD5+, CD4+, CD8+, SBU-T19+, MHC class II+, T80+ and sIg+) of lymphocytes in blood, and in prescapular and ileocaecal efferent lymph of sheep, have been determined. The similarity in the distribution of lymphocyte subsets in both lymph compartments indicated that the non-random migration of lymphocyte populations to peripheral lymph nodes and gut could not be due to preferential migration of a particular lymphocyte subset such as CD4+ or CD8+ cells to one tissue. Marked differences in the percentage of lymphocyte subsets between blood and efferent lymph suggested that some lymphocyte subsets leave the blood with differing efficiencies and that differential extraction of lymphocyte subsets from blood by a lymph node may be due to subset-specific lymphocyte-endothelial interactions.

Effect of interferon-alpha-2a on the output of recirculating lymphocytes from single lymph nodes

The output of recirculating lymphocytes from cannulated popliteal lymph nodes in sheep was measured after administration of human recombinant interferon (rIFN)-alpha-2a. Interferon (IFN) injection caused a dramatic decrease in lymphocyte output from lymph nodes. Following a single s.c. or i.d. injection of 2 x 10(7) U IFN into the drainage area of the popliteal lymph node, lymphocyte output fell to below 1% of the pre-treatment level and remained depressed for up to 35 hr. A substantial decrease in lymphocyte output from cannulated nodes also occurred after IFN was injected either i.v., into the skin of the opposite non-cannulated hind leg or into an afferent lymphatic vessel leading to the popliteal lymph node. After the period of depressed lymphocyte output, a seemingly compensatory surge of cell traffic occurred that lasted 2-3 days. During this phase there was a relative increase in the proportion of CD4+ T cells in lymph. Similar changes occurred after each treatment in animals given multiple doses of IFN. These effects are unlikely to be antigen-induced since there was no blast cell response in any treated animal. The analysis of blood and lymph plasma samples showed that the most severe depression of lymphocyte output was associated with high levels of IFN, while there was no apparent correlation between the reduction in lymphocyte traffic and concentrations of cortisol in plasma. These results suggest that IFN-alpha-2a is involved directly in the regulation of lymphocyte output from lymph nodes.

Mucosal immunity: the immunology of breast milk

The mammary glands represent one part of the mucosal immune system, a definable, subunit of humoral and cellular immune functions in man that appears to have developed particular qualities well suited to guard our interface with the environment. As our understanding of secretory immunoglobulins and lymphocyte migration patterns continues to develop, the immunologic components found in breast milk appear increasingly likely to play a specific immunologic role in the protection of the nursing infant. The biologic basis for the observed protective effect of breast-feeding is reviewed with an emphasis on the mechanisms involved in the development and maintenance of mucosal immunity in general.

Lymphocyte migration and differentiation in a large-animal model: the sheep

The size and docility of the sheep permit various surgical interventions and repeated collections of biological samples. Development of lymphatic cannulation techniques in this species enabled the investigation of the kinetics of lymphocyte migration in single lymph nodes of not only postnatal animals but also of fetuses at various stages of gestation. It was first demonstrated in the sheep that lymphocyte recirculation commences in the fetus without any exogenous antigenic stimulus. Using these cannulation techniques, it is also possible to investigate humoral events such as the secretion of lymphokines taking place in single lymph nodes with regard to the regulation of lymphopoiesis and the immune response. An extracorporeal perfusion system has been used successfully to investigate the emigration of cells from various lymphoid organs in the sheep. This apparatus enables cells to be labelled in their normal microenvironment with radioisotopes and/or fluorescent probes without destroying the normal tissue architecture. In studies with outbred animals such as the sheep, an investigation in which an individual animal is studied as a case history over a long time often provides much more information than studies based on single-point examinations of many animals and is much closer to the clinical study of immunological problems in individual humans. The recent development of an array of monoclonal antibodies against lymphocyte surface antigens in sheep will help to further dissect the complexity of immunological phenomena. Therefore, the sheep is a useful animal model to study physiological events taking place in the lymphoid system, and in vivo studies in this species will continue to offer a great potential for research of biological relevance and supplement the research done on the in vitro manipulation of cells and biological products related to the immune system.

A dual laser analysis of the migration of XRITC-labeled, FITC-labeled, and double-labeled lymphocytes in sheep

Substituted rhodamine isothiocyanate (XRITC) has been used to study lymphocyte migration in sheep. After being labeled in vitro with XRITC, lymphocytes appeared in the efferent lymph of single lymph nodes with the same kinetics as cells labeled with fluorescein isothiocyanate (FITC). The recovery of intravenously injected XRITC-labeled cells was followed in lymph for several days. The kinetics and recoveries were compared with data obtained using FITC, chromium-51, and indium-111. XRITC was found to be a suitable label and, using dual laser (argon and krypton) flow cytometry, it could be analyzed simultaneously with FITC. In addition, it was possible to relabel FITC-stained cells with XRITC after they were recovered in lymph. The migratory characteristics of such double-labeled cells were not different from single-labeled cells.

The organization of cell populations within lymph nodes: their origin, life history and functional relationships

The normal lymph node comprises a superficial cortex, a deep cortex or paracortex and a medulla. In each of these regions there are three kinds of spaces: an intralymphatic space, an intravascular space and an extravascular space or interstitium. Both the vascular endothelium and the lymphatic endothelium are specialized in these different regions. The cell types in lymph nodes comprise lymphoid cells, accessory or non-lymphoid cells and stromal cells, and within these cell types a number of different sub-types can now be identified by means of enzyme- and immunocytochemistry. Based predominantly on experimental studies, the origin, migratory patterns, localization, inter-relationships and interactions between these various cells are reviewed.

Relation of intra-splenic migration of marginal zone B cells to antigen localization on follicular dendritic cells

Injection of heat-killed Escherichia coli into rats results in massive loss of IgM + ve, IgD - ve B cells from the marginal zones of their spleen within 4 hr. This is matched by a concomitant increase of cells with this phenotype in the splenic follicles. The marginal zone remains depleted and the follicles distended for about 16 hr, but the histological picture returns to normal within 24 hr. Surface marker analysis of blood and spleen B lymphocyte populations throughout the course of the migration suggest that there is intrasplenic migration of IgM + ve cells from marginal zone to follicles rather than via the circulation. Factors inhibiting localization of immune complex on follicular dendritic cells were assessed for their influence on marginal-zone B cell migration. Immune complex, injected 5 hr post-endotoxin administration localized poorly on follicular dendritic cells. While C3 depletion, by cobra venom, has no effect on marginal-zone B cell migration induced by endotoxin, it completely inhibits transport of heat-aggregated human gammaglobulin to follicular dendritic cells.

The interaction of high endothelial venules with T and B cells in peripheral lymph nodes after antigenic stimulation

The influence of an ongoing immune response on the specific interaction of high endothelial venules (HEV) in peripheral lymph nodes with T and B cells was determined using short-term homing experiments and an in vitro HEV adherence assay. It was demonstrated that stimulation with various antigens did not change the receptor specificity of the HEV. However, the retention and/or the efflux of immigrant cells in the stimulated lymph nodes had changed.

The migration of blood-borne lymphocytes into rat popliteal lymph nodes stimulated with xenogeneic red blood cells

The recruitment of radiolabelled blood-borne lymphocytes into rat popliteal lymph nodes (PLN) was investigated following the injection of varying doses of chicken (CRBC) or sheep red blood cells (SRBC) into the hind foot pad. Within the dose range tested (10(5)-10(8) RBC) an increase in the dose of injected antigen resulted in elevated levels of lymphocyte recruitment into the draining popliteal lymph node. The kinetics of lymphocyte recruitment with the same dose of CRBC or SRBC was similar even though these red cells differ in size and are antigenically non-cross-reactive. While little is known of the mechanisms which control the rate of entry of blood-borne lymphocytes into antigen-stimulated lymph nodes, the extent of lymphocyte recruitment was shown to be directly related to the quantity of antigen injected.

Cellular and humoral IgA responses after single and multiple local injections of antigen

IgA responses in submandibular salivary glands, cervical lymph nodes, and saliva of rats were studied. Immunoglobulin-containing cells of the IgA isotype were examined by immunofluorescence of mononuclear cells isolated from the submandibular salivary glands and cervical lymph nodes after primary and multiple local injections of Streptococcus mutans. Also, salivary and serum antibodies to S. mutans were determined using an ELISA. The results support immunologic memory for the secretory (salivary) IgA system at both the cellular and humoral levels. Comparison of the dynamics of the IgAICC responses among the tissues and secretions after the injection regimes suggests that the cervical lymph nodes may provide an enriched tissue source for secretory IgA responses in the oral cavity.

The effect of vitamin A depletion on antigen-stimulated trapping of peripheral lymphocytes in local lymph nodes of rats

The effect of vitamin A depletion on antigen-stimulated trapping of peripheral lymphocytes in lymphatic organs was studied in rats. Distribution of [3H]-uridine-labelled syngenic peripheral lymphocytes was quantified by assaying radioactive content of brachial and axillary lymph nodes, spleen and liver of normal and vitamin A-depleted F344/Ducrj rats immunized with sheep red blood cells. Localization of labelled cells in the ipsilateral brachial lymph nodes of the normal rats was stimulated by three times upon immunization with sheep erythrocytes as compared with the contralateral nodes. Recruitment of cells in axillary lymph nodes, spleen and liver was not significantly different from non-immunized values. The vitamin A-depleted rats exhibited marked deterioration in antigen-stimulated trapping of labelled cells in the draining brachial lymph nodes. These results suggest that this effect of vitamin A depletion is due to derangement of integrity of lymphocyte-trapping mechanism in the draining lymph nodes and not to any change in nature of lymphocytes per se.

Assessment of in vivo natural antitumor resistance and lymphocyte. Migration in mice: comparison of 125I-iododeoxyuridine with 111indium-oxine and 51chromium as cell labels

Clearance of IV-injected tumor cells has been correlated with levels of natural killer (NK) cell activity in recipient animals. Studies of in vivo tumor cell clearance strongly suggest a relationship between levels of NK cell activity and antitumor or antimetastatic effector function. This study outlines the applicability of three radiolabels, [125I]iododeoxyuridine, ( [125I]dUrd), indium-111-oxine chelate ( [111In]Ox), and chromium-51 (51Cr), to studies of tumor cell clearance in vivo. The suitability of these labels for analysis of the in vivo migration patterns of normal lymphocytes or thymus-derived T cells cultivated in vitro (CTC) is also discussed. The results indicate that [111In]Ox and 51Cr compare favorably with the more widely used [125]dUrd as radiolabels for the assessment of IV-injected tumor cell clearance from the lungs of mice. The rates of clearance of both [111In]Ox and 51Cr, like that for [125I]dUrd, correlate closely with levels of NK-cell activity of the host. Further studies with [111In]Ox reveal that treatment of recipients with anti-asialo GM1 serum, a regimen known to suppress NK-cell activity, demonstrates the appropriate reduction in isotope clearance from the lungs after NK suppression. However, clearance data obtained by monitoring levels of radioactivity in the liver after IV injection must be viewed cautiously, since the same cells labeled with [111In]Ox and [125I]dUrd had a different pattern of clearance from the liver. The same inconsistencies in clearance were observed when [111In]Ox and [125I]dUrd were injected intrafootpad (i.f.p.). Similar effects were observed when [111In]Ox or 51Cr was applied to studies of CTC migration. Levels of [111In]Ox and 51Cr remained high in the liver after IV injection, while [125I]dUrd was rapidly cleared. Normal spleen or thymic lymphocytes exhibited the expected homing to the spleen after labeling with [111In]Ox, indicating a suitability of this label for migration studies, except possibly in the liver. These results with CTC and normal lymphocytes should be considered during the formulation of immunotherapy protocols based on cell migration data, since the choice of radiolabel can result in widely divergent levels of radioactivity accumulated in some organs, and may not provide an accurate representation of the presence of viable, intact, or functional cells.

Early changes in lymphocyte traffic between distant lymph nodes following regional antigenic stimulation

Regional labeling of mice by injection of cytidine-3H ([3H]CR) into the footpad of the left hind leg was used to evaluate lymphocyte traffic from the left regional nodes to the right popliteal lymph node (PLN) within a 24-h period, with or without concomitant primary or secondary stimulation of the right PLN with fluid tetanus toxoid. Results indicate that 1) in the case of primary antigen injection the relative contribution of lymphocytes from the left regional nodes to the small lymphocyte population present in the stimulated right PLN 24 h after labeling was slightly, but not significantly, greater than in non-stimulated controls; 2) a booster injection of antigen into the right hind leg footpad resulted in a significantly smaller relative contribution of lymphocytes from the previously primed left regional nodes to the small lymphocyte population in the right PLN, 24 h after injection of [3H]CR and secondary stimulation, as compared with controls or animals given a primary stimulation to the receiver node; and 3) in contrast to controls and mice subjected to primary stimulation only, the right PLN 24 h after booster contained a significant number of large lymphoid cells which, or whose precursors, had migrated to this site from contralateral nodes within a day, possibly also in the form of small lymphocytes. These findings are discussed in relation to the problem of lymphocyte recruitment and divergent behavior of non-committed lymphocytes as compared with memory cells in the initial phase after primary or secondary antigenic stimulation.

Cyclosporin-A inhibits accumulation of lymphocytes within lymph nodes

The ability of cyclosporin-A (CS-A) to modify lymphocyte accumulation, seen in lymph nodes draining a site of antigen deposition, has been compared with the effect of other drugs known to affect lymphocytes and/or macrophages. CS-A markedly inhibited lymphocyte accumulation in a dose-related manner, whereas aspirin, BW755c (3 amino 1 [m (trifluoromethyl) phenyl] 2-pyrazoline) and hydrocortisone were without effect. Indomethacin produced inconclusive results. The time of CS-A administration was critical, the drug needing to be present before antigen inoculation, being ineffective if given 23 hr after antigen.

Differential effector functions of central and peripheral compartments of immune response system: characterization of immune responses in the spleen and mesenteric lymph nodes to directly injected sheep red blood cells

When sheep red blood cells (SRBC) were injected intraperitoneally (i.p.), intravenously (i.v.), or into the Peyer's patches, definite plaque-forming cell (PFC) and rosette-forming cell (RFC) responses were induced in the spleen but not in the mesenteric lymph nodes (MLN). When SRBC were injected directly into the spleen or MLN, stronger PFC and RFC responses were induced in the spleen or MLN, respectively, than when injected i.p. or i.v. PFC response induced in MLN by injecting SRBC into MLN with or without the polysaccharide of Klebsiella pneumoniae type 1 Kasuya strain (CPS-K) as an immunological adjuvant was weaker than that induced in the spleen by injecting the antigen into the spleen. Direct PFC (PFC of IgM type) and RFC responses induced in the spleen by injecting SRBC into MLN were rather stronger than those induced in the spleen by injecting the antigen into the spleen. In contrast, no significant responses were induced in MLN by injecting SRBC into the spleen, and no definite indirect PFC (PFC of IgG type) response was induced in the spleen by injecting the antigen into MLN. The levels of whole immunological memory as well as isolated B- or T-cell memory in the spleen and MLN of mice injected with SRBC directly into the spleen or MLN were determined by using an in vitro assay system. Definite amounts of either B- or T-cell memory were detected in the spleen of mice injected with SRBC directly into the spleen of MLN. Smaller amounts of memory were detected in MLN injected with SRBC directly into the spleen. Moreover, the amounts of whole memory detected in MLN were much less than compared with those of isolated T- and B-cell memories in MLN. Further experiments showed that in vitro expression of the memories preserved in MLN required supplement of glass non-adherent cells from normal spleen. Based on these results, we discussed the possible differential and collaborative functions of the central (spleen) and peripheral (MLN) immune response systems in antibody responses.

Recruitment of functional subpopulations of T lymphocytes. Initiator T lymphocytes recruit helper T cells for cytotoxic response

Initiator T (Ti) lymphocytes are defined by their ability to recruit other T cell populations in vivo. In this study the function of T cells recruited into draining lymph nodes following injection of Ti cells primed to alloantigens in mixed lymphocyte culture was examined. The results demonstrate that alloantigen-specific helper T cells that interact with cytotoxic T (Tc) lymphocyte precursors are recruited, as shown by the significantly higher frequencies of helper cells in draining lymph nodes compared with controls. However, neither Tc cells nor their precursors are recruited. Recruitment by Ti lymphocytes is therefore selective for certain T cell subsets. Proposals to explain the mechanism, specificity, and selectivity of recruitment are discussed. We suggest that Ti cells have a central role in both the initiation of T cell-dependent immune responses and in the maintenance of immunologic memory. Their function is the rapid mobilization of T cell subclasses to a regional lymphoid organ where the immune response subsequently develops.

[Functional significance of reactive histologic changes in lymph nodes (author's transl)]

Being a reservoir of lymphocytes and plasma cells the lymph nodes are an integral part of the immune system. B and T lymphocytes in the lymph nodes show a distinct topographical distribution. The follicular outer cortex and the medullary cords are predominantly populated by B cells. The paracortical zone between cortex and medulla, is again subdivided in T cell areas and regions with heterogeneous populations of T and B lymphocytes. Even in the normal state nodal lymphocytes maintain a permanent exchange with blood lymphocytes via the mechanism of lymphocyte recirculation. Reactive structural changes of immunologic origin result in an increased immigration of blood lymphocytes into, as well as in local clonal proliferation within the lymph nodes. Four different morphologic patterns of nodal reaction can be determined in terms of functional impact: (1) cortical plasma cell reactions, (2) paracortical plasma cell reactions, (3) germinal center reactions, all three associated with humoral immune responses, and (4) hyperplastic changes of the paracortex associated with cell-mediated immune reactions. In both humoral and cell-mediated immune responses there may be an additional sinus histiocytosis, or mast cell hyperplasia.

The sequence of changes in blood flow and lymphocyte influx to stimulated rat lymph nodes

The rat popliteal lymph node was studied from 1 hr to 8 days after the footpad injection of either sheep erythrocytes or syngeneic rat erythrocytes. The following were measured relative to the contralateral (unstimulated) lymph node: (i) blood flow; (ii) lymph node weight; (iii) influx of lymphocytes from the blood; (iv) [3H]-thymidine incorporation; (v) [35S]-sulphate incorporation into macromolecular form (chiefly by high endothelial venules). After the arrival of sheep erythrocytes all five quantities showed substantial increases which began in a definite sequence. The blood flow started to rise first and may have been the main factor contributing to the later increase in lymphocyte influx. Increased sulphate incorporation began later than the rise in lymphocyte influx. After the injection of rat erythrocytes a small increase in lymphocyte influx was found without a corresponding increase in blood flow. In rats irradiated before the footpad injections lymphocyte influx increased three-fold after sheep erythrocytes, rat erythrocytes or PBS, again without a corresponding increase in blood flow. Thus while variation in blood flow to high endothelial venules is one important factor in determining the supply of lymphocytes to the lymph node other factors are operative in certain situations.

Lymphocyte traffic through antigen-stimulated lymph nodes. I. Complement activation within lymph nodes initiates cell shutdown

Complement activation within lymph nodes has been shown to alter lymphocyte traffic through the node. Challenge of cannulated sheep lymph nodes with either immune complexes or complement activators was found to initiate the phenomenon of cell shutdown associated with antigenic challenge of lymph nodes in primed animals.

Lymphocyte traffic through antigen-stimulated lymph nodes. II. Role of Prostaglandin E2 as a mediator of cell shutdown

Prostaglandin E2 (PGE2) can mediate changes in lymphocyte traffic through lymph nodes. By measuring PGE2 levels in efferent lymph from cannulated sheep lymph nodes it was shown that increased synthesis of PGE2 always correlated with cell shutdown; infusion of PGE2 alone induced cell shutdown and inhibition of PGE2 synthesis by the node abolished cell shutdown induced by antigen.

Tridimensional study of the deep cortex of the rat lymph node. IV. Differential labelling of the deep cortex units with 3H-uridine

Using tridimensional reconstruction, it was recently found that the deep cortex of rat lymph nodes comprises one to several basic "units." Each unit is a semi-rounded structure contiguous to the peripheral cortex and bulging into the medulla of a node. Other investigators reported that transfused lymphocytes, heavily labelled in vitro by 3H-uridine, became concentrated in an ill-defined region of nodes, referred to as the mid and deep cortex. This suggested to us that the in vivo labelling of nodes with 3H-uridine might allow to further characterize the units on a physiological basis. Therefore, rats were injected intravenously with a dose of 1--20 muCi of 3H-uridine/gm body weight and sacrificed 1 hour to 3 days later. The radioautographs of their nodes were exposed up to 535 days. The observations revealed that a large dose of 3H-uridine combined with a long exposure of the radioautographs yielded a differential labelling of the cell population of the units, characterized by a much more intense reaction than that of the surrounding structures. This demonstrated that the physiology of the lymphocyte population of the deep cortex units differs from the morphologically similar lymphocyte population of the extrafollicular zone of the peripheral cortex. The possible reason(s) for the differential labelling of the units is discussed.

Age-related changes in cell localization and proliferation in lymph nodes and spleen after antigenic stimulation

Antigen-dependent localization of 51Cr-labelled lymphocytes, and the subsequent uptake of IUdR into lymphoid organs has been studied as a function of age. Measures of cell localization indicated that while old age can alter the patterns of entry of lymphocytes into lymph nodes and spleen, these changes are variable and probably not sufficient alone to explain decreased primary antibody responses in old animals. Proliferation of cells, however, was consistently affected in both organs and this phenomenon is discussed in terms of abnormal T-cell function.

Measurement of lymphocyte traffic with indium-111

This study was designed to assess the use of 111indium as a radioactive marker for the investigation of lymphocyte recirculation in the sheep. Lymphocytes were collected from sheep with indwelling catheters in the efferent lymphatic ducts of peripheral lymph nodes and labelled with 111In-oxine or Na2 51CrO at doses of 10 microCi and 50 microCi/10(8) cells respectively. After intravenous injection the lymphocyte specific activity (c.p.m./10(7) cells) in blood and lymph was measured for several days. The maximum specific activity in efferent lymph was twelve-fold greater with 111In than with 51Cr-labelled cells. The kinetics of lymphocyte traffic as measured in double labelling experiments was very similar. The modal transit time was 21.6 hr with each isotope. The recovery of 111In-labelled cells was not significantly different from cells labelled with 51Cr. In vivo viability of the labelled cells was further supported by the normal proliferative response observed with 111In-labelled lymphocytes compared to unlabelled cells in the normal lymphocyte transfer reaction. In conclusion, 111In-oxine is an excellent radioactive label for lymphocytes in the sheep. Because of its high counting efficiency and cell labelling characteristics one can label as few as 10 million lymphocytes, or a subpopulation of cells, and assess their recirculation.

Comparative histological studies of regional lymph nodes of 201 melanoma patients. (Microscopic features in relation to individual age, site, and metastatic spread)

Since May 1968 a total of 2.108 regional lymph nodes (l.n.) dissected from 201 melanoma patients (86 axillary, 107 groin, and 8 neck) have become available for study. The purpose was to detect histological differences between the l.n. of 134 patients lacking and those of 67 patients exhibiting l.n. metastases, histologically verified in 104 of 706 nodes. The main finding is a more than six-fold increase in number and an eleven-fold increase in total area (evaluated by a microscope micrometer) of germinal centers in the lymph follicles of patients with, as compared to those without, l.n. metastases (P less than or equal to 0.05). Paracortical areas were found to be diminished in 56.7% of cases with metastatic spread. Accumulations of plasma cells were mainly seen in the nodes of elderly patients (48.4%) and of those exhibiting regional metastases (47.8%). The observation of numerous and dilated blood vessels in the interfollicular regions noticeably corresponded to the occurrence of lymphatic metastases (P less than or equal to 0.01), suggesting a "tumor angiogenic factor". A negative correlation with metastatic involvement was found as to histiocytosis of marginal sinuses and with respect to the observed fibrinoid hyalinosis of pulp vessels (P less than or equal to 0.01). The marked hyperplasia of lymph node B-lymphocyte regions as opposed to diminished T-lymphocyte areas prevailing in cases with metastatic melanoma is in accord with findings of humoral immunologic blocking activity and impaired T-cell response in advanced malignant melanoma.

Regional blood flow and its relationship to lymphocyte and lymphoblast traffic during a primary immune reaction

The relationship of alterations in blood flow with changes in cell distribution has been studied in an inflammatory site and its draining lymph node during the induction of an immune reaction with oxazolone in mice. The cells which move to the site of inflammation are predominantly lymphoblasts and their increased localization in the inflamed ear is significantly correlated with increased regional blood flow to the inflamed tissue. The existence of this correlation is not antigen dependent although there is a relative increment of lymphoblasts which are specifically primed to the inflammatory agent. The localization of nonblastic (small) 51Cr-labeled lymphocytes on the other hand is substantial only in lymphoid tissue and during the induction of an immune reaction after oxazolone application, the increase in localization of these cells in the draining lymph node is positively correlated with increased blood flow to the node. Furthermore, the probability of finding 51Cr labeled lymphocytes in a particular lymph node is related to the regional blood flow which that node receives.

Kinetics of prostaglandin production in various inflammatory lesions, measured in draining lymph

Efferent lymph was collected over long periods via catheters surgically placed in popliteal and prefemoral lymph nodes of sheep. Prostaglandin (PG) E and F equivalents were measured with a radioimmunoassay. After stimulation with heat-killed Escherichia coli, PG levels rose dramatically in the efferent lymph but were undetectable in the contralateral control lymphatics or in the systemic circulation. When E coli were infused directly into a lymph node, the PG levels in the effluent lymph were inhibited with indomethacin. Carrageenan, delayed hypersensitivity, and lymphocyte transfer reactions were also studied. In the classic acute inflammations (caused by E coli and carrageenan) the PG levels rose early in the response (first 4 to 6 hours) compared with delayed production in the immune reactions. With PPD, PG levels peaked between 10 and 20 hours after injections, while PG rose 127 hours after allogeneic lymphocytes were injected. These results are discussed in relation to the role of PG in inflammation, and the use of the sheep lymphatic model in PG research is emphasized.

Changes in lymphocyte accumulation and proliferation in the lymph nodes draining the pregnant uterus

Changes in weight, lymphocyte accumulation and cellular proliferation have been measured in the lymph nodes draining the uterus during inter- and intra-strain pregnancies and compared with similar effects after other antigenic stimuli. From the data obtained it was concluded that "paternal" antigenic stimulation from the conceptus initiated an immune response in these nodes. The mechanisms of the subsequent suppression of this response are discussed.

Effect of Peptichemio upon Localization of Injected Radiolabelled Lymphocytes in the Lymphatic Organs of Antigen - Stimulated Mice

Increased localization (trapping) of lymphocytes occurs in lymphoid organs following antigenic challenge. The effect of peptichemio (PTC) upon lymphocyte trapping in lymph nodes and spleen was investigated: the results demonstrate that the drug diminishes trapping in lymphatic organs. The depression of lymphocyte trapping may provide at least one mechanism whereby PTC achieves its immunosuppressive effects.

Migratory behavior of lymphocytes with specific reactivity to alloantigens. II. Selective recruitment to lymphoid cell allografts and their draining lymph nodes

A dual-antigen, dual-isotope assay has been used to monitor the migratory behavior of selectively labeled antiallogeneic lymphocytes in mice challenged subcutaneously in all four foot pads with semiallogeneic spleen cells. 3H-labeled anti-C3H and 14C-labeled anti-C57BL lymphocytes of DBA/2J origin were pooled and adoptively transferred to multiple groups of previously challenged DBA/2J recipients. In some of the studies, separate groups of recipients were challenged with either CDF or BDF spleen cells in all four paws, whereas in others CDF spleen cells were used to challenge the right paws of each mouse in the group and BDF spleen cells to challenge the left paws of each mouse in the group. At intervals varying from 24 to 96 h after challenge, a subgroup of four mice from each appropriate group was sacrificed and the relative numbers of anti-C3H and anti-C57BL lymphocytes present in the challenged paws, draining lymph nodes, and other tissues of each mouse were inferred from the mean 3H/14C ratios of the respective tissues of that subgroup. The results of these studies firmly establish that specific antiallogeneic lymphocytes are selectively recruited to the paws and draining lymph nodes of mice challenged subcutaneously in the foot pads with semiallogeneic spleen cells and are deleted from their circulating blood and nondraining lymph nodes. A mechanism for antigen-induced selective recruitment and its possible functional significance in tumor immunology are discussed.

Selective accumulation of cells with 'B' properties in stimulated lymph nodes

Draining lymph nodes from mice which had been stimulated with bacterial adjuvants or the skin sensitizing agent, oxazolone, showed a marked increase in cell content, presumably due to lymphocyte immigration. A surprisingly large proportion of these cells exhibit properties of B lymphocytes: the presence of surface Ig, lack of Thy-1-like antigen and responsiveness to lopopolysaccharide (LPS). The relationship between the presence of surface markerand responses to class-specific mitogens, of cells from the stimulated nodes, was established by testing fractionated lymphocyte populations. Enriched T cells did not react to LPS, whereas removal of cells with Thy-1 antigen by specific antisera eliminated the reactions to T mitogens but had little or no effect on the LPS response. The data thus suggest that B cells, which make up a small portion of the circulating lymphocyte pool, are selectively accumulated in lymph nodes stimulated by different immunogens, including T-specific stimulants. This interpretation contradicts the generally accepted assumption, that stimulat lymph nodes trap mostly T lymphocytes.

Two distinct pools of recirculating T lymphocytes: migratory characteristics of nodal and intestinal T lymphocytes

A pronounced asymmetry in the recirculation from blood to lymph of resting small recirculating T lymphocytes is described. When 51Cr-labeled small T-recirculating lymphocytes (TRL) from intestinal lymph were infused intravenously their relative recovery in intestinal lymph was about twice that in nodal lymph. In contrast, the relative recovery in nodal lymph of 51Cr-labeled nodal TRL was twice that in intestinal lymph. Intestinal TRL migrated in large numbers through the small intestine. Nodal TRL did not. It is proposed that the pool of recirculating small T lymphocytes consists of two major subdivisions, an intestinal pool and a nodal pool. The nodal circulation comprises small TRL which traverse PCV in all lymph nodes (LN) but not the small intestine. The intestinal circulation comprises small TRL which do not traverse PCV in LN, but which do recirculate through the small intestine from which they pass via afferent lymphatics to the mesenteric LN and subsequently via the thoracic duct into the blood. It is suggested that the intestinal circulation is present in the fetus and that its initial development is independent of extrinsic antigen.