Activity Of Lymph Node Cells Research Articles

Design, Synthesis, and Immunosuppressive Activity of New Deoxybenzoin Derivatives

In the search for potential immunosuppressive agents with high efficacy and low toxicity, a series of new deoxybenzoins were synthesized and evaluated for their cytotoxicity and immunosuppressive activity. Among the synthesized compounds, four deoxybenzoin oximes (compounds 31, 32, 37, and 38) exhibited lower cytotoxicity and higher inhibitory activity toward anti-CD3/anti-CD28 co-stimulated T-cell proliferation than other compounds. More significantly, compound 31 is >100-fold less cytotoxic than cyclosporine A (CsA) and is also more potent (31: SI>684.64, CsA: SI=235.44). The preliminary inhibition mechanism of compound 31 was also identified by flow cytometry, and this compound exerts immunosuppressive activity by inducing apoptosis in activated lymph node cells in a dose-dependent manner. In addition, the mechanism of apoptosis was detected by western blot analysis.

Stress as an endogenous adjuvant: augmentation of the immunization phase of cell-mediated immunity

Stress is thought to be immunosuppressive but paradoxically exacerbates inflammatory and autoimmune diseases. We initially showed that acute stress enhances skin immunity. Such immunoenhancement could promote immunoprotection in case of wounding, infection or vaccination but could also exacerbate immunopathological diseases. Here we identify the molecular and cellular mediators of the immunoenhancing effects of acute stress. Compared with non-stressed mice, acutely stressed animals showed significantly greater pinna swelling and leukocyte infiltration, and up-regulated macrophage chemoattractant protein-1, macrophage inflammatory protein-3alpha, IL-1alpha, IL-1beta, IL-6, tumor necrosis factor-alpha and IFN-gamma, but not IL-4 gene expression at the site of primary antigen exposure. Stressed animals also showed enhanced maturation and trafficking of dendritic cells (DCs) from skin to lymph nodes (LNs), higher numbers of activated macrophages in skin and LNs, increased T cell activation in LNs, and enhanced recruitment of surveillance T cells to skin. These findings show that important interactive components of innate (DCs and macrophages) and adaptive (surveillance T cells) immunity are mediators of the stress-induced enhancement of a primary immune response. Such enhancement during primary immunization may induce a long-term increase in immunologic memory resulting in subsequent augmentation of the immune response during secondary antigen exposure. Thus, the evolutionarily adaptive fight-or-flight stress response may protectively prepare the immune system for impending danger (e.g. infection and wounding by a predator), but may also contribute to stress-induced exacerbation of inflammatory and autoimmune diseases.

Allergen‐induced cytokine phenotypes in mice: role of CD4+ and CD8+ T cell populations

CD4+ T cells expressing type 2 cytokines have been implicated in the pathogenesis of asthma to high-molecular-weight allergens. Topical exposure of BALB/c strain mice to low-molecular-weight chemical contact and respiratory allergens stimulates type 1 and type 2 cytokine secretion phenotypes, respectively. To examine the relative frequencies of cytokine-positive CD4+ and CD8+ T cells and their contributions to these cytokine secretion profiles. Methods Draining auricular lymph nodes were isolated 13 days after initiation of topical exposure of female BALB/c strain mice to chemical allergen, or to vehicle alone. The frequency of intracellular cytokine (IL-4 and IFN-gamma)-positive CD4+ and CD8+ lymphocytes was enumerated by flow cytometry. The relative contribution of CD4+ and CD8+ cells to cytokine secretion profiles was assessed by negative selection. Exposure to allergen resulted in an increased frequency of both IFN-gamma+ CD4+ and CD8+ lymphocytes, although there were no marked differences between trimellitic anhydride (TMA)- and 2,4-dinitrochlorobenzene (DNCB)-activated lymph node cells. Treatment with TMA induced approximately five times as many IL-4+ CD4+ cells as did exposure to DNCB. This pattern of cytokine staining was also observed for a further pair of contact and respiratory allergens; respectively, formalin and fluorescein isothiocyanate. These data demonstrate that the divergent immune responses induced in mice by different classes of chemical allergen are independent of changes in the frequency of IFN-gamma+ cells, but are associated with differential frequencies of IL-4-expressing CD4+ T cells.

Selective Haptenation of Cellular or Extracellular Protein by Chemical Allergens: Association with Cytokine Polarization

Sensitizing chemicals can cause different forms of allergy, allergic contact dermatitis, or sensitization of the respiratory tract. These discrete types of chemicals induce in mice qualitatively divergent immune responses; contact allergens provoke preferential type 1 responses, whereas respiratory allergens stimulate selective type 2 responses. We have questioned whether the ability of chemicals to initiate polarized immune responses is in part a function of the nature of their association with protein. Cytokine secretion profiles provoked following topical exposure of BALB/c mice to dinitrochlorobenzene (DNCB), dinitrofluorobenzene (DNFB), fluorescein isothiocyanate (FITC), trimellitic anhydride (TMA), and dinitrobenzenesulfonyl chloride (DNBSCl) were compared with the distribution of covalent binding to U937 cells and/or to serum proteins in vitro. DNCB and DNFB each provoked a type 1 cytokine secretion profile, with high levels of IFN-gamma, but relatively low levels of type 2 cytokines IL-4, -5, and -10. The converse selective type 2 phenotype was seen following equivalent exposure to TMA, FITC, or DNBSCl. Each chemical bound covalently to U937 cells and to serum proteins, when incubated with cells or serum alone. When incubated with cells and serum together, DNCB and DNFB bound selectively to cellular protein, whereas TMA, FITC, and DNBSCl bound selectively to serum. These investigations show that the distribution of antigen formation of chemical allergens in an in vitro model system segregates with the type of cytokines secreted from activated lymph node cells in an in vivo mouse model. Chemical allergens that stimulate type 1 cytokine secretion profiles bind selectively to cellular proteins, whereas others that provoke type 2 cytokine profiles bind preferentially to serum proteins.

CD4+ T cell depletion during all stages of HIV disease occurs predominantly in the gastrointestinal tract.

The mechanisms underlying CD4+ T cell depletion in human immunodeficiency virus (HIV) infection are not well understood. Comparative studies of lymphoid tissues, where the vast majority of T cells reside, and peripheral blood can potentially illuminate the pathogenesis of HIV-associated disease. Here, we studied the effect of HIV infection on the activation and depletion of defined subsets of CD4+ and CD8+ T cells in the blood, gastrointestinal (GI) tract, and lymph node (LN). We also measured HIV-specific T cell frequencies in LNs and blood, and LN collagen deposition to define architectural changes associated with chronic inflammation. The major findings to emerge are the following: the GI tract has the most substantial CD4+ T cell depletion at all stages of HIV disease; this depletion occurs preferentially within CCR5+ CD4+ T cells; HIV-associated immune activation results in abnormal accumulation of effector-type T cells within LNs; HIV-specific T cells in LNs do not account for all effector T cells; and T cell activation in LNs is associated with abnormal collagen deposition. Taken together, these findings define the nature and extent of CD4+ T cell depletion in lymphoid tissue and point to mechanisms of profound depletion of specific T cell subsets related to elimination of CCR5+ CD4+ T cell targets and disruption of T cell homeostasis that accompanies chronic immune activation.

Effective photoimmunotherapy of murine colon carcinoma induced by the combination of photodynamic therapy and dendritic cells.

The unique mechanism of tumor destruction by photodynamic therapy (PDT), resulting from apoptotic and necrotic killing of tumor cells accompanied by local inflammatory reaction and induction of heat shock proteins (HSPs), prompted us to investigate the antitumor effectiveness of the combination of PDT with administration of immature dendritic cells (DCs). Confocal microscopy and Western blotting were used to investigate the influence of PDT on the induction of apoptosis and expression of HSP expression in C-26 cells. Confocal microscopy and flow cytometry studies were used to examine phagocytosis of PDT-treated C-26 cells by DCs. Secretion of interleukin (IL)-12 was measured with ELISA. Cytotoxic activity of lymph node cells was evaluated in a standard (51)Cr-release assay. The antitumor effectiveness of PDT in combination with administration of DCs was investigated in in vivo model. PDT treatment resulted in the induction of apoptotic and necrotic cell death and expression of HSP27, HSP60, HSP72/73, HSP90, HO-1, and GRP78 in C-26 cells. Immature DCs cocultured with PDT-treated C-26 cells efficiently engulfed killed tumor cells, acquired functional features of maturation, and produced substantial amounts of IL-12. Inoculation of immature DCs into the PDT-treated tumors resulted in effective homing to regional and peripheral lymph nodes and stimulation of cytotoxic activity of T and natural killer cells. The combination treatment with PDT and administration of DCs produced effective antitumor response. The feasibility and antitumor effectiveness demonstrated in these studies suggest that treatment protocols involving the administration of immature DCs in combination with PDT may have clinical potential.

Long Term iNOS Expression in Thoracic Lymph Nodes of Silicotic Rats

Beside the lung, thoracic lymph nodes are most affected during silicosis. The mechanisms leading to enlargement of the lymph nodes and partial activation of lymph node cells are still unclear. The present study demonstrates an increase in iNOS mRNA expression in the lung draining lymph nodes of rats at 1, 2, and 8 months following silica exposure. Histopathological analysis revealed that iNOS protein was exclusively expressed by macrophages located within the granulomatous areas of the enlarged lymph nodes. In contrast, no differences in mRNA expression and number of iNOS-positive cells were found in the lungs of silica-exposed and non-exposed rats. In vitro experiments showed that silica particles alone did not induce NO release in primary alveolar macrophages (AMs) or the alveolar macrophage cell line NR8383. However, the addition of interferon (IFN)-gamma led to a significant nitric oxide production by primary AMs. NR8383 cells responded only when a combination of IFN-gamma and silica particles was applied. These results indicate that the macrophage activator IFN-gamma, which has already been shown to be expressed at elevated levels by lymphocytes of the silicotic lymph nodes, may be responsible for the long-lasting iNOS expression in thoracic lymph nodes. Our observations support the hypothesis that the mutual activation of lymphocytes and macrophages is a central process in the development of chronic silicosis.

Impaired activation of islet-reactive CD4 T cells in pancreatic lymph nodes of B cell-deficient nonobese diabetic mice.

Despite the impressive protection of B cell-deficient (muMT(-/-)) nonobese diabetic (NOD) mice from spontaneous diabetes, existence of mild pancreatic islet inflammation in these mice indicates that initial autoimmune targeting of beta cells has occurred. Furthermore, muMT(-/-) NOD mice are shown to harbor a latent repertoire of diabetogenic T cells, as evidenced by their susceptibility to cyclophosphamide-induced diabetes. The quiescence of this pool of islet-reactive T cells may be a consequence of impaired activation of T lymphocytes in B cell-deficient NOD mice. In this regard, in vitro anti-CD3-mediated stimulation demonstrates impaired activation of lymph node CD4 T cells in muMT(-/-) NOD mice as compared with that of wild-type counterparts, a deficiency that is correlated with an exaggerated CD4 T cell:APC ratio in lymph nodes of muMT(-/-) NOD mice. This feature points to an insufficient availability of APC costimulation on a per T cell basis, resulting in impaired CD4 T cell activation in lymph nodes of muMT(-/-) NOD mice. In accordance with these findings, an islet-reactive CD4 T cell clonotype undergoes suboptimal activation in pancreatic lymph nodes of muMT(-/-) NOD recipients. Overall, the present study indicates that B cells in the pancreatic lymph node microenvironment are critical in overcoming a checkpoint involving the provision of optimal costimulation to islet-reactive NOD CD4 T cells.

Role of CD4(+) T helper 2-type cells in cutaneous inflammatory responses induced by fluorescein isothiocyanate.

Owing to its skin-sensitizing and fluorochromatic properties, fluorescein isothiocyanate (FITC) is employed frequently as an experimental hapten in mechanistic studies of contact allergy, particularly in the context of the role of migration and activation of Langerhans' cells. In this study we demonstrated that topical exposure of mice to FITC results in the selective development of activated lymph node cells (LNC) expressing a preferential type 2 cytokine-secretion profile, with high levels of interleukin (IL)-4 and IL-10, but low levels of interferon-gamma (IFN-gamma). Negative selection (complement depletion) identified CD4(+) T helper (Th)2-type cells as the primary source in activated LNC of the type 2 cytokines IL-4 and IL-10, whereas the low levels of IFN-gamma produced were derived exclusively from CD8(+) T cytotoxic (Tc) 1-type cells. A biphasic pattern of cutaneous inflammatory reactions was elicited by exposure to FITC, the early phase of which could be transferred passively with serum (presumably immunoglobulin E [IgE] antibody), whereas adoptive transfer experiments demonstrated that Th2-type CD4(+) cells were responsible for the delayed-type component of the dermal hypersensitivity reaction. In contrast with contact allergic reactions induced by other sensitizing haptens, which are considered to be largely Th1/Tc1-mediated immune processes regulated by Th2-type cells, these results suggest therefore that the skin lesions provoked in mice by FITC are primarily a result of the activation of Th2-type cells.

Increased activity of lymph node cells in experimental thermal injury: changes in accessory cells in injured area-draining lymph nodes

Accessory cell content and some of their functional characteristics were determined in regional lymph nodes which drain burn injury (DLN) in rats. Increase in percentages of non-specific esterase-positive cells and NBT+ macrophages and in numbers of dendritic cells were noted in cytospin preparations of draining lymph node cells (DLC) 24 and 72 h following thermal injury. An accumulation of B cells was also noted in the DLN paracortex region at these time points. Enrichment of ED1+ (rat macrophage marker) cells was noted in the adherent DLC population. Increased activity of interleukin-1 (IL-1) in conditioned medium from adherent DLC population and the increased stimulatory capacity of whole DLC or dendritic cell enriched-DLC fraction were noted in functional assays. Enrichment in accessory cells and an increase in their functional activity could contribute to the endogenous activity of regional lymph nodes which drain burned areas.

Autocrine Regulation of IL-12 Receptor Expression Is Independent of Secondary IFN-γ Secretion and not Restricted to T and NK Cells

AbstractThe biological response to IL-12 is mediated through specific binding to a high affinity receptor complex composed of at least two subunits (designated IL-12Rβ1 and IL-12Rβ2) that are expressed on NK cells and activated T cells. The selective loss of IL-12Rβ2 expression during Th2 T cell differentiation suggests that regulation of this receptor component may govern IL-12 responsiveness. In murine assays, down-regulation of IL-12Rβ2 expression can be prevented by treatment with IFN-γ, indicating that receptor expression and hence IL-12 responsiveness may be regulated, at least in part, by the local cytokine milieu. In this study, we report that cellular expression of both IL-12Rβ1 and β2 mRNA is increased in the lymph nodes of naive mice following systemic administration of murine rIL-12 (rmIL-12). Changes in IL-12R mRNA were associated with increased IFN-γ secretion following ex vivo activation of lymph node cells with rmIL-12, indicating the presence of a functional receptor complex. Expression of IL-12R mRNA was not restricted to lymph node T cells, and its autocrine regulation was independent of secondary IFN-γ secretion. Data from fractionated lymph node cells as well as rmIL-12-treated B cell-deficient mice suggest that IL-12-responsive B cells may represent an alternative cellular source for IFN-γ production. However, the strength of the biological response to rmIL-12 is not governed solely by receptor expression, as rmIL-12-induced IFN-γ secretion from cultured lymph node cells is accessory cell dependent and can be partially blocked by inhibition of B7 costimulation.

Ex vivo activation of tumor-draining lymph node T cells reverses defects in signal transduction molecules.

The adoptive transfer of tumor-draining lymph node (LN) T cells activated ex vivo with anti-CD3 and interleukin 2 (IL-2) mediates the regression of the poorly immunogenic murine melanoma D5. The efficacy of the activated LN cells is augmented when the sensitizing tumor is a genetically modified variant (designated D5G6) that secretes granulocyte/macrophage-colony-stimulating factor. In contrast to anti-CD3/IL-2-activated LN cells, adoptive transfer of freshly isolated tumor-draining LN T cells has no therapeutic activity. To determine whether the acquisition of antitumor function during ex vivo activation is associated with modifications in signal transduction capacity, the protein tyrosine kinases p56lck and p59fyn and proteins of the NF-kappaB family were analyzed in tumor-draining LN T cells. The levels of p56lck and p59fyn were lower in tumor-draining than in normal LN T cells and production of tyrosine-phosphorylated substrates was markedly depressed following anti-CD3 stimulation. After 5-day anti-CD3/IL-2 activation, levels of p56lck and p59fyn and protein tyrosine kinase activity increased. Interestingly, the levels of p56lck, p59fyn, and tyrosine kinase activity were higher in activated T cells derived from LN that drained D5G6 than they were in those from D5 tumors. In contrast, the cytoplasmic levels of c-Rel and Rel A were normal in freshly isolated tumor-draining LN, as was nuclear kappaB DNA-binding activity induced by anti-CD3 mAb or phorbol myristate acetate. Stimulation of activated LN cells with D5 tumor cells induced the nuclear translocation of NF-kappaB. These findings indicate that the recovery of proteins mediating signal transduction through the T cell receptor/CD3 complex in LN T cells activated ex vivo was associated with the acquisition of antitumor function.

A modification of the local lymph node assay for contact allergenicity screening: measurement of interleukin-2 as an alternative to radioisotope-dependent proliferation assay

The local lymph node assay is an effective prediction method for contact allergenicity, but employs radioisotopes. We investigated whether measurement of interleukin-2 (IL-2) production by lymph node cells could be used instead to predict contact allergenicity of chemicals. Test chemicals were applied for three consecutive days to both ears of Balb/c mice and the auricular lymph nodes were obtained on either the fourth or fifth day after the first application. Both IL-2 concentration in supernatant of the suspension and proliferative activity of lymph node cells were determined after 24-, 48-, 72-h cell culture in RPMI-1640 medium by ELISA and by measuring [ 3H]methylthymidine incorporation, respectively. These two methods detected allergenicity similarly except in the case of TNCB and oxazolone, which showed excessive proliferation-inducing capacity as compared to IL-2 release-increasing effect. Flow cytometry showed that these two chemicals also increased the percentage of Ia d-positive cells in the lymph nodes, suggesting that these chemicals might induce not only cellular immunity but also humoral immunity. We conclude that interleukin-2 assay is a convenient and dependable method for screening strong contact allergens without using radioisotopes.

Analysis of effector T cells against the murine syngeneic tumor MethA in mice orally administered antitumor polysaccharide SPR-901.

The growth of MethA tumor was significantly inhibited by oral administration of the alpha-glucan SPR-901 in BALB/c (+/+) mice but not in nude mice. Mice treated orally with SPR-901 exhibited an augmentation of antigen-specific resistance against rechallenge with the tumor cells. The tumor-neutralizing activity of regional lymph node cells from MethA-bearing mice against the tumor was augmented by oral administration of SPR-901. The tumor-neutralizing activity of lymph node cells from SPR-901-treated mice mainly appeared in Lyt2+ cells. Furthermore, lymphokine-activated killer activity of these cells was enhanced by administration of SPR-901. The antitumor effect of SPR-901 was abrogated in mice depleted of either L3T4+ or Lyt2+ cells, and in cyclosporin-A-treated mice. These results suggest that Lyt2+ cells are important effector cells in MethA-bearing mice orally administered SPR-901 and that functional exertion of both Lyt2+ and L3T4+ T cells is necessary for the antitumor effect of orally administered SPR-901 in vivo.

The regulation of the expression of gp39, the CD40 ligand, on normal and cloned CD4+ T cells.

Studies have established that gp39, the ligand for CD40, induces B cell cycle entry and is involved in the initiation of the humoral immune response. Expression of gp39 has been observed on normal, activated CD4+ T cells, activated lymph node cells; an activated Th1 clone, and an activated Th2 clone. Anti-CD3-activated CD8+ T cells did not express gp39; however, CD8+ T cells activated with PMA/ionomycin expressed gp39. The kinetics of anti-CD3-induced gp39 expression on a T cell clone and on splenic CD4+ T cells showed that gp39 was detectable at 4 h after activation, reaching maximal levels between 6 to 8 h postactivation and returning to near resting levels between 24 to 48 h. Lymphokines modulated the expression of gp39 on activated T cells. Expression of gp39 was inhibited by IFN-gamma on activated Th1, Th2, and CD4+ T cells; whereas TGF-beta inhibited gp39 expression only on the Th2 clone studied. All other lymphokines tested were without substantial effect. Differences in the expression of gp39 on activated naive and memory T cells were observed, as well as differences in requirements for optimal gp39 expression on these subsets. There are correlations between gp39 expression and effector function; however, anti-CD3-activated splenic CD4+ cells that express gp39 did not exhibit effector function. A comparison of the relative numbers of molecules of gp39 shows that activated Th1 clones express at least 20-fold the number of gp39 molecules/cell compared with activated splenic CD4+ cells. This may imply that density of gp39 on the activated T cells plays an important role in determining effector function.

Experimental allergic encephalomyelitis: Neutralizing antibody to TGFβ1 enhances the clinical severity of the disease

Experimental allergic encephalomyelitis (EAE) is a well established model for the human autoimmune disease multiple sclerosis. Recently, we and others have shown that the administration of TGFβ is therapeutically effective in reducing incidence and severity of EAE. Here we show that the addition of anti-TGFβ1 to myelin basic protein (MBP)-activated lymph node cells enhance the T cell proliferative response by 28% in vitro and in vivo and that injections of anti-TGFβ1 antibody worsen EAE both in incidence and severity. Further, an inverse relationship was observed in the amount of IL-2 and TGFβ detected in MBP stimulated culture supernatants. We show that IL-2 decreases from 248 U/ml at 48 h to non-detectable at 96 h, while TGFβ increases from 0.5 ng/ml to 1.2 ng/ml, respectively. These observations further indicate a role for endogenous TGFβ1 in the immunoregulation of EAE.

A combination of adoptive transfer and antigenic challenge induces consistent murine experimental autoimmune encephalomyelitis in C57BL/6 mice and other reputed resistant strains

Adoptive EAE was induced in SJL mice by the transfer of MBP-primed and in vitro-stimulated donor lymph node cells into naive syngeneic recipients. Priming donor mice with OVA instead or restimulating MBP-primed donor cell with OVA resulted in no transfer of EAE. This apparent lack of disease, however, could be overcome if the recipients were subsequently challenged with MBP. When this transfer-challenge technique was applied to BALB/c and C57BL/6 mice, these reputed (MBP)EAE-resistant strains developed consistent and severe disease similar to that seen in susceptible strains. In fact, a survey of eleven (MBP)EAE-resistant strains, defined on the basis of their inability to mount an encephalitogenic response in recipient mice following the transfer of MBP-primed and in vitro activated lymph node cells, revealed that EAE could be induced in all these strains. Since the surveyed strains represented a wide spectrum of genetic backgrounds as well as the common MHC congenic haplotypes (H-2 b,d,k,m,r,s,v), it is concluded that the machinery for recognition of MBP, i.e. MHC genes and the appropriate T cell receptors, is functionally intact in these resistant mice. While MHC and T cell receptor genes are required for T cell responses, they are not the limiting factors that confer resistance in murine EAE.

Potential of human lymph node cells for antitumor activity mediated by interferon gamma

The soluble antitumor activity of regional lymph node cells obtained from patients with cervical cancer was investigated by using a human tumor clonogenic assay (HTCA). A significant antiproliferative activity of the lymph node cells (LNCs) against a cervical cancer cell line, HeLa cells, was demonstrated by stimulation with either phytohemagglutinin (PHA) or concanavalin A (Con A), but not with interleukin-2 (IL-2). This antiproliferative activity of LNC was found in nonadherent cells, possibly T-cells. By using neutralizing antibody experiments, this activity was found to be attributed to interferon gamma (IFN gamma), but not to tumor necrosis factor (TNF), although both cytokines were produced from LNC. These results indicate that human LNC was able to exert an antiproliferative activity mediated through the cytokines by appropriate stimulation.

Immunität der Haut — Infektion und perkutane Immunisierung von Kaninchen mit E. coli ATCC 13676

After intracutaneous infection of rabbits with a suspension of E. coli which was followed by a transient local inflammation, the local and systemic immune responses were determined using the lymphocyte stimulation test (LTT) and the hemolysis plaque assay (HPA). Lymphocytes of the lymphatic system draining the infected skin area and blood lymphocytes were used. With lymphocytes derived from the local lymph nodes, a substantial increase of specific stimulation in the LTT was detected beginning at day 3 after infection and lasting up to the termination of the experiment (3 weeks). Blood lymphocytes were stimulated at a lower level: The activity showed a peak at day 4 and an elevated level only during a 10-day period. After the intracutaneous infection with E. coli, increasing numbers of antibody-releasing lymph node cells were detected in the HPA. The antibody-secreting cells of the IgM and IgG classes clearly showed an increasing specificity for E. coli lipopolysaccharide coupled to sheep red blood cells. As with the LTT, the highest activities (values of specificity and number of plaque-forming lymphocytes) were observed at the end of the experimental period. An emulsified preparation of a heat-inactivated E. coli culture ( E. coli-BKS) which had been applied locally onto the artificially altered skin evoked a similar immunological response after a 2 or 3-weeks treatment. In such animals an increased activity of lymph node cells could be registered by LTT and HPA as compared to reactions from placebo-treated control animals. However, the topical immunization with nonviable E. coli stimulated not only lymphocytes which produced antibodies directed specifically against E. coli lipopolysaccharide as demonstrated by the HPA. An increased number of lymphocytes reacted even with native sheep red blood cells. This observations is discussed in respect of a polyclonal B-cell activation by lipopolysaccharide of the E. coli-BKS.

Adoptive transfer of experimental autoimmune thyroiditis (EAT) with in vitro activated lymph node cells from thyroglobulin-sensitized guinea pigs: characterization of the cell that transfers EAT.

Relatively low numbers of lymph node cells (LNC) from Strain 2 or Strain 13 guinea pigs sensitized with guinea pig thyroglobulin (GPTG) could transfer experimental autoimmune thyroiditis (EAT) to normal syngeneic recipients after in vitro culture with GPTG. The EAT induced in recipients of cultured LNC was similar in incidence and severity to EAT induced by active immunization with GPTG in complete Freund's adjuvant. The cells that were effective in transferring EAT were shown to be immunoglobulin-negative, nylon wool nonadherent, and Ia-negative. The effector cells were sensitive to irradiation after in vitro activation, indicating that cell proliferation in the recipient is required for development of EAT. Recipient animals often developed moderate to severe lesions of EAT yet none had detectable delayed hypersensitivity to GPTG and the majority also had no detectable anti-GPTG antibody.