Biomedical subjects

N Bloksma

Publications and source records attributed to N Bloksma.

At least 37 records · Page 2Linked to original sources

PubMed1995

Immune effects of hexachlorobenzene in the rat: role of metabolism in a 13-week feeding study.

The role of metabolism and porphyria in the immunomodulating effects of hexachlorobenzene (HCB) was investigated. To this end, female Wistar rats received a diet with two different doses of HCB and pentachlorobenzene (PCB), either in combination or not with the cytochrome P450IIIA1 inhibitor, triacetyloleandomycin (TAO). Urinary metabolites and urinary and liver porphyrins were measured at regular intervals and data have been published elsewhere. Skin lesions were scored weekly and after 13 weeks of exposure lymphoid organs were weighed, spleens were examined by morphometry, and serum.(auto)antibody levels were determined by ELISA. The probability of causal relationships between the different parameters was determined by analysis of correlation. HCB caused a dose-dependent increase of the incidence, but not the severity, of skin lesions, and dose-dependently increased weights of popliteal lymph nodes and spleen and serum levels of IgM, IgA, and autoantigen-specific IgM. IgG and IgG autoantibody levels were not changed. The splenomegaly could be attributed to an expansion of all splenic compartments. PCB caused no skin lesions and had only minor, predominantly immunosuppressive effects. TAO virtually lacked immunomodulating activity of its own, hardly affected the induction of skin lesions by HCB, did not change the immune effects of HCB, and suppressed IgG levels when combined with PCB. Comparison of the immunological data with those found in the same rats as to induction of porphyria and biotransformation of HCB and PCB, indicates that the HCB-induced porphyria, being markedly reduced by coadministration of TAO, is not involved in the immunomodulating effects of HCB. The same conclusion could be drawn for the oxidative HCB metabolites, since TAO inhibited their formation, while the same metabolites were formed upon administration of PCB that lacked the immunostimulatory effects of HCB. Therefore, HCB itself, its nonoxidative metabolites, or their precursors are likely candidates for inducing the immune effects. Further, an immune component in the HCB-induced skin lesions, usually associated with dermal porphyrin accumulation, is suggested by the observations that TAO profoundly reduced induction of porphyria, but not of skin lesions and immune effects, by HCB.

Adjuvants, Immunologic↗

PubMed1995

Predictive immunotoxicological test systems: suitability of the popliteal lymph node assay in mice and rats.

This article reviews results obtained with popliteal lymph node assays (PLNAs) in rodents and discusses their ability to detect and analyze immunotoxic effects of drugs and other low molecular weight (LMW) chemicals. In its basic form, the PLNA measures activation of the draining lymph node of the hind paw (i.e., the PLN) after injection of a test chemical into the hind foot pad. The assay appears to be appropriate to recognize sensitizing, that is, allergenic and autoimmunogenic, chemicals, as well as nonsensitizing immunostimulatory chemicals. With modifications, PLNAs can detect immunosuppressive chemicals and distinguish sensitizing from nonsensitizing chemicals. Furthermore, modified PLNAs enable detection of known as well as unknown sensitizing metabolites, and may assist in the identification of the self-molecules that act as carriers for chemical sensitization or as targets of chemical-induced autoimmune disease. Experience with PLNAs shows that they are rapid, reproducible, and objective tests for recognition of sensitizing or otherwise immunomodulating chemicals. Because current protocols of toxicity testing are insensitive in predicting a chemical's potential to result in immunomodulation, PLNAs, when further validated, may provide welcome supplements to routine toxicity screening of chemicals, thus enhancing chemical safety.

Animals↗

PubMed1994

Long-term treatment with 5,5-diphenylhydantoin reduces lymphadenopathy and anti-ssDNA autoantibodies in C57BL/6-lpr/lpr mice.

To further the insight in the immunomodulating properties of the anticonvulsant 5,5-diphenylhydantoin (DPH), C57BL/6 (B6), C57BL/6-lpr/lpr (B6-lpr/lpr) and MRL/MpJ- +/+ (MRL) mice received DPH orally for six months to determine weekly urinary biopterin levels, a potential T-cell activation marker, by high performance liquid chromatography. At the end of the experiment serum antibody levels were measured by ELISA and relative lymphoid organ weights determined. DPH treatment resulted in reduced body weight in all strains, reduced spleen weights in B6 and MRL mice, profoundly reduced popliteal lymph node weights in B6-lpr/lpr mice and increased thymus weights in MRL mice. DPH treatment decreased serum IgM, IgG and IgA as well as IgM and IgG anti-ssDNA levels in B6-lpr/lpr mice, but did not affect these parameters in other strains. Effects of DPH on IgM rheumatoid factor levels in B6-lpr/lpr mice were inconsistent. Urinary biopterin levels of untreated B6 and B6-lpr/lpr mice were about equal and lower than those of MRL mice. During the first three months of DPH treatment, persistently elevated biopterin levels were observed in B6 and to a lesser degree in MRL mice, and alternately elevated and control levels in B6-lpr/lpr mice. Thereafter, the effects faded in all strains. Results show that long-term DPH treatment causes only minor lymphoid organ weight changes in B6 and MRL mice, but causes a clear reduction of the lymphadenopathy and (auto)antibody formation in B6-lpr/lpr mice. Observed changes could not be related to altered biopterin excretion indicating that the latter is an inappropriate marker of murine autoimmune disease.

Animals↗

PubMed1994

Selective inhibition of immature CD4-CD8+ thymocyte proliferation, but not differentiation, by the thymus atrophy-inducing compound di-n-butyltin dichloride.

Effects of the thymus atrophy-inducing organotin compound di-n-butyltin dichloride (DBTC) on the differentiation and proliferation of immature rat thymocyte subsets were studied in vivo and in vitro. Incubation of freshly isolated CD4-CD8- or immature CD4-CD8+ (characterized as CD4-CD53-) thymocytes with 10(-7) M DBTC for 18 hr did not affect cell recovery or their ability to differentiate to CD4-CD8+ cells and CD4+CD8+ or to CD4+CD8+ cells, respectively. The same treatment decreased the spontaneous as well as the phytohaemagglutinin (PHA)-induced proliferation in both subsets. However, the inhibition of proliferation by DBTC of immature CD4-CD8+, but not of CD4-CD8- thymocytes, appeared to increase with their growth rate. Data show that differentiation of immature thymocytes can proceed independently of proliferation and that DBTC causes thymus atrophy by selectively inhibiting the proliferation of immature CD4-CD8+ thymocytes. Administration to rats of DBTC via the diet for 14 days resulted in an initial decrease of thymoblast number by day 2, followed by a decrease in the total number of thymocytes by day 4. Total thymocyte numbers were lowest on day 7 and did not significantly change thereafter. CD4/CD8 thymocyte subset distributions were similar to controls on day 4, but on day 7 of feeding a marked reduction of the percentage of CD4+CD8+ thymocytes and consequently an increase of the percentages of the three other CD4/CD8 subsets were found. Thereafter, the CD4/CD8 subset distribution recovered, reaching near control values on day 14, despite the very low numbers of thymoblasts and of total thymocytes at that time. Data together indicate that DBTC reduces the production of CD4+CD8+ and mature single-positive thymocytes by selectively inhibiting immature CD4-CD8+ thymocyte proliferation but without affecting the differentiation capacity of these cells. This suggests that thymocyte proliferation and differentiation are separately regulated processes.

Animals↗

PubMed1993

Autoimmune effects of hexachlorobenzene in the rat.

We investigated whether autoimmune disregulation underlies the formerly reported induction of IgM hypergammaglobulinemia and lymphoid organ enlargement by hexachlorobenzene (HCB) in rats. To this end blood, liver, and lymphoid organs were collected from male Wistar rats after feeding a semisynthetic diet containing 0, 500, or 1000 mg HCB/kg for 3 weeks. Sera prepared from the blood were analyzed for total and (auto)antigen-specific antibody levels by ELISA, organs were weighed, and spleens were further investigated morphologically using immunohistochemically stained cryosections. Present experiments confirmed the ability of HCB to increase total IgM, but not IgG, levels and to increase relative spleen, lymph node, and liver weights. HCB treatment elevated IgM, but not IgG, levels against single-stranded DNA, native DNA, rat IgG (representing rheumatoid factor), and bromelain-treated mouse erythrocytes that expose phosphatidylcholine as a major autoantigen. Antibody levels against the foreign antigens sheep erythrocytes, tetanus toxoid, and bovine serum albumin remained unaffected. The IgM autoantibodies proved to be polyreactive. Morphometric analysis of spleen sections showed that HCB caused a proportionally equal expansion of all splenic compartments, but when individual spleen weights were taken into account a significantly larger expansion of the predominantly B cell-containing marginal zones could be noted. The latter compartment also contained an increased number of macrophages that can be recognized by the monoclonal antibody ED3. The ability of HCB to elevate serum antibody levels against autoantigens, but not foreign antigens, indicates that HCB probably does not act by polyclonal B cell activation. The IgM isotype, the repertoire, and the polyreactivity of the serum autoantibodies suggest that HCB activates a recently described B cell subset shown to be committed to the production of these autoantibodies and associated with various systemic autoimmune diseases. Since the marginal zone is considered to be the splenic lodging site of this B cell subset and since increases of ED3+ macrophages have been associated with autoimmune diseases in the rat, the observed changes of the marginal zones in HCB-treated rats is in line with this notion.

Animals↗

PubMed1993

Recovery from chemically induced thymus atrophy starts with CD4- CD8- CD2high TcR alpha beta-/low thymocytes and results in an increased formation of CD4- CD8- TcR alpha beta high thymocytes.

Regeneration of the thymus was studied in rats that were treated with a single oral dose of the organotin compound di-n-butyltin dichloride (DBTC). After an initial maximum depletion of cortical BrdU+ thymocytes on day 2 after treatment, repopulation appeared to start on day 3 as indicated by an increased number of BrdU+ cells in the subcapsular region. On day 5, when thymocyte depletion was most pronounced, a relative increase of BrdU+ cells was observed all over the cortex. In comparison with controls, the thymoblast population on day 5 appeared to harbour increased numbers of CD4- CD8- and immature CD4- CD8+ CD53- thymoblasts, while the number of CD4+ CD8+ blasts had decreased. In comparison with day 3, however, the number of CD4+ CD8+ blasts had increased again. Results together have been interpreted as indicative for thymus regeneration starting from CD4- CD8- blasts which differentiate to immature CD4- CD8+ and then to CD4+ CD8+ blasts. Further characterization revealed that the majority of the CD4- CD8- and CD4- CD8+ CD53- blasts expressed high levels of CD2 and no or low levels of T-cell receptor (TcR) alpha beta. The high expression of CD2 on repopulating thymoblasts may be an additional indication of their activated state and for a role of interaction with the ligand LFA-3 on thymic epithelial cells during this phase of thymocyte differentiation. The number of CD4- CD8- TcR alpha beta high cells was increased on day 5 after dosing. The origin of this population and the possible implication of its development during thymus regeneration after chemically induced thymus atrophy are discussed.

Animals↗

PubMed1991

Role of tumour necrosis factor in the tumour-necrotizing activity of agents with diverging toxicity.

We investigated the ability of various tumour-necrotizing agents with diverging toxicity to induce tumour necrosis factor (TNF) and cytostatic activity in Propionibacterium-acnes-primed Swiss and tumour-bearing BALB/c mice, and the capacity of anti-TNF antibodies to inhibit induction of tumour necrosis by the agents. Lipid A and especially its combination with muramyl dipeptide induced high TNF levels in Swiss mice, as measured in the serum. Lower levels were induced by detoxified lipid A and the nontoxic dsRNA, polyadenylic.polyuridylic acid, either alone or combined with muramyl dipeptide. The toxic agents also appeared the strongest inducers of mediators with cytostatic activity against cultured endothelial cells and MethA tumour cells. Anti-TNF antibodies partially reduced the cytostatic activity of the sera against MethA cells. Tumour-bearing BALB/c mice produced only low levels of TNF and cytostatic factors in response to all agents. Recombinant mouse TNF hardly reduced the DNA synthesis of MethA cells, unless normal mouse serum was added. Serum from P.-acnes-treated Swiss mice and tumour-bearing BALB/c mice, that were inhibitory on their own, failed to potentiate the action of TNF. Serum from Swiss mice treated with toxic, but not detoxified, lipid A caused extensive tumour necrosis upon injection into MethA-bearing BALB/c mice. This activity was completely abolished by pre-incubation of the serum with anti-TNF. The tumour-necrotizing activity of the agents could be partially reduced by prior injection of these antibodies. Results show that the capacity of the agents to induce TNF and cytostatic activity is not related to their antitumour potential. Although TNF is likely to be a crucial mediator of the tumour-necrotizing action of the toxic as well as the nontoxic agents, it is probably not the sole mediator. Data also indicate that induction of tumour necrosis does not require induction of high and, thus toxic, TNF levels in the serum.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1991

Urinary biopterin levels in mice during graft-versus-host reactions and during exposure to 5,5-diphenylhydantoin.

Based on evidence that urinary neopterin levels are useful markers of disordered cellular immunity in man, we investigated murine urinary biopterin excretion during acute and chronic graft-versus-host (GvH)-reactions as well as after oral exposure to drugs with documented immune disregulating potential in man. Biopterin levels were determined in urine spot samples by reversed-phase high performance liquid chromatography and expressed in relation to the urinary creatinine content. Similarly increased and decreased biopterin levels were observed during acute and chronic GvH-disease in (C57BL/6J x DBA/2J)F1 (B6D2F1) mice. Increased and/or decreased levels of urinary biopterin were observed during treatment with 5,5-diphenylhydantoin (DPH), methimazole, propylthiouracil and nitrofurantoin, but no consistent pattern could be distinguished. The DPH-induced alterations were similar in B6 and B6D2F1 mice, were dose-dependent, reversible and independent of mature T-cells, as judged by the pronounced biopterin excretion of B6-nu/nu mice in comparison with their T-cell competent litter mates. The results indicate that monitoring of urinary biopterin excretion in mice does not represent a useful biochemical marker for T-cell activation.

Animals↗

PubMed1991

Popliteal lymph node enlargement and antibody production in the mouse induced by drugs affecting monoamine levels in the brain.

Drugs that affect monoamine levels in the brain were screened for their potential to cause immunological changes in the popliteal lymph node (PLN) of mice after injection into the hind paw. The tricyclic antidepressant (TCA) drugs, imipramine and amitriptyline, and the serotonin reuptake blocker, zimeldine, induced a prominent PLN weight gain in C57BL/6 mice. Ketanserin and ritanserin appeared less effective while nomifensine, serotonin and the antigen, sheep erythrocytes, lacked significant activity. In BALB/c mice all agents induced an increase of PLN cell number, the TCA drugs and zimeldine appeared superior in this respect. Increased IgM as well as IgG production on a per cell basis was only induced by the TCA drugs, zimeldine and, especially, sheep erythrocytes. Data indicate that induction of PLN responses is not a general property of agents affecting monoamine levels. Structural, i.e. antigenic, characteristics of the drugs rather than their pharmacological properties are probably at play.

Animals↗

PubMed1990

Kinetics and morphology of chemically induced popliteal lymph node reactions compared with antigen-, mitogen-, and graft-versus-host-reaction-induced responses.

Changes in the popliteal lymph node (PLN) in mice evoked by a local graft-versus-host (GVH) reaction and by a single injection of various agents into the hind footpad were compared. The drug diphenylhydantoin induced similar weight changes in time as the GVH reaction. More vigorous and protracted reactions were induced by the drug nitrofurantoin and the contact sensitizer dinitrochlorobenzene, whereas the antigens lipopolysaccharide and sheep erythrocytes caused very moderate and short-lasting weight changes. Alterations of lymph node architecture upon injection of diphenylhydantoin resembled those observed during the GVH response. Some quantitative and qualitative differences were noted for nitrofurantoin, but clearly deviant morphological alterations were seen in response to lipopolysaccharide and sheep erythrocytes. The PLN reaction to dinitrochlorobenzene had features of both the GVH reaction and the antigen-induced responses. These findings support the concept that some drugs and chemicals may induce or exacerbate lymphoproliferative disorders by GVH-like mechanisms.

Animals↗

PubMed1990

Popliteal lymph node enlargement and antibody production in the mouse induced by zimeldine and related compounds with varying side chains.

Structural requirements for induction of draining lymph node responses by the antidepressant drug zimeldine ((Z)-3-(4-bromophenyl)-N,N-dimethyl-3-(3-pyridyl)allylamine) in mice were determined by comparison of its activity with that of metabolites and analogues having different side chains. Mice received 1.0 mg of the compounds into the hind footpad and the popliteal lymph nodes (PLN) were removed 7 days later to determine weight, cell number and antibody production. Compounds with a methylated (Z)-(homo)allylamine side chain induced a marked PLN weight gain in C57BL/6 mice and a significant increase of the PLN cell number and of the IgM and IgG production per 10(6) PLN cells in BALB/c mice. Moderate PLN weight increase, but no significant antibody formation was induced by the doubly demethylated zimeldine metabolite, while compounds without an aliphatic amine or having a saturated side chain lacked significant activity in all assays. The (E)-diastereomer of zimeldine induced significantly less PLN weight gain than zimeldine in C57BL/6 mice, but an equal increase of PLN cell number in BALB/c mice. IgM and IgG responses to the (E)-diastereomer were moderate and absent, respectively. The antihistaminic drug, brompheniramine, having a saturated side chain and a 2-pyridyl ring, induced less PLN weight and cell gain than zimeldine and failed to increase antibody formation. The capacity of the compounds to induce PLN responses appeared not related to their pharmacological potential to inhibit the reuptake of serotonin and noradrenaline.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Induction of popliteal lymph node enlargement and antibody production in the mouse by pyridylallylamines related to zimeldine.

The role of the para-brominated phenyl ring of the allylamine antidepressant drug, zimeldine, in its immunomodulating activity was studied by comparing local lymph node responses of mice to analogues with various phenyl ring substituents. The compounds (1.0 mg) were injected into the hind footpad and weight and cell number of the popliteal lymph node (PLN) and antibody production by PLN cells were determined 7 days later. Zimeldine and the para-trimethylsilylated and ortho-para-chlorinated compounds induced a marked PLN weight gain in C57BL/6 mice. The para-chlorinated and meta-brominated analogues were significantly less effective, while the para-fluorinated and the unsubstituted analogue failed to trigger PLN weight gain. The same range of potency of the compounds was seen when increases of PLN cell number in BALB/c mice and increases of IgM production by a fixed number of BALB/c PLN cells were determined. The IgG production on a per cell basis was not increased by the fluorinated and the unsubstituted compounds, while the remaining compounds stimulated the IgG production to a similar extent. Plots of the lipophilicity of the para-substituted compounds against their ability to induce PLN weight and cell gain showed a fair correlation, but induction of antibody formation tended to be counteracted at too high lipophilicity. No correlation between pharmacologic and immunologic activity of the compounds could be found. Data indicate that lipophilicity grossly favours PLN enlargement, but the divergent responses to the equilipophilic 3- and 4-brominated compounds, suggest conformational restraints as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Effect of tumour necrosis factor and lipid A on functional and structural vascular volume in solid murine tumours.

Effects of recombinant tumour necrosis factor (TNF) on functional and structural vascular volumes in solid murine Meth A tumours were investigated by injection of Hoechst 33342 and staining for the vascular basement membrane component laminin, respectively. Systemic injection of 3 x 10(4) U TNF caused an initial increase in functional volume in the tumour, but a strong decrease from 1 to 48 h after treatment. Early effects of intralesional treatment were more moderate. Systemic injection of 10(4) U TNF or 0.3 or 3 micrograms lipid A caused a fall in functional volume at 4 h, but a recovery was seen at 24 h. This recovery did not occur after treatment with a combination of 10(4) U TNF and 0.3 micrograms lipid A. Structural vascular volume was not markedly reduced until 24 h after treatment with the high doses of the separate agents and the combination. All effects appeared generally more prominent in the tumour centre than in the borders. Data suggest that TNF induces initially an active hyperaemia that rapidly converts to passive hyperaemia. A prolonged disturbance of tumour blood supply is probably necessary for therapeutic activity. Breakdown of laminin in the vascular basement membrane may be a cause of loss of vascular integrity.

Animals↗

PubMed1989

Macroscopic and microscopic early effects of tumour necrosis factor on murine Meth A sarcoma, and relation to curative activity.

Mice with solid Meth A sarcoma in the skin received an intravenous or intralesional injection of graded doses of recombinant human tumour necrosis factor (rTNF). Local treatment caused red discolouration and necrosis of the central portion of the tumour within 24 h over a larger range of doses than intravenous treatment. Effects showed a limited dose dependence and no significant correlation with subsequent cures, which were far more frequent after local treatment. A dose of rTNF that induced about equal macroscopic necrosis by both routes caused much more pronounced microscopic effects after local administration. Effects included mitotic arrest, granulocyte margination, endothelial damage, hyperaemia, congestion, oedema, and tumour cell necrosis. rTNF did not affect the Meth A cells in vitro. Locally injected skins showed moderate vascular effects which were more marked in tumour-bearing mice, but skin necrosis was absent. Data show that quantitative histology rather than macroscopically visible necrosis correlates with cure rates. A broad interference of rTNF with tumour blood supply seems to be a major cause of the induced necrosis. Granulocytes may be involved in vascular damage. The different effects of rTNF on skin and tumour indicate that tumour vasculature has enhanced susceptibility to rTNF and probably lesser repair capacity.

Animals↗

PubMed1989

Synergic action between tumor necrosis factor and endotoxins or poly(A.U) on cultured bovine endothelial cells.

In order to investigate whether direct effects on tumor vasculature may contribute to induction of necrosis of solid tumors in vivo, agents and combinations with an established different capacity to induce tumor necrosis were studied for their effects on endothelial cells in vitro. Tumor necrosis serum caused a marked inhibition of [3H]thymidine incorporation by bovine umbilical cord endothelial cells after 4 h coincubation. Endotoxin was less inhibitory, whereas detoxified endotoxin and recombinant human tumor necrosis factor (rTNF) were hardly active in concentrations that can be achieved in vivo. Combinations of rTNF and (detoxified) endotoxin caused synergic inhibition. By 24 h effects of the separate agents and synergic effects of the combinations were much stronger. The nontoxic dsRNA, poly(A.U), also had inhibitory activity, and acted synergistically with rTNF. Morphologically, a combination of endotoxin and rTNF but not the separate constituents induced marked cell detachment by 24 h, an indication of cell death. Whereas both endotoxin and rTNF inhibited DNA synthesis of human endothelial cells, the agents did not act synergistically on these cells. The ability of the agents and the combinations to affect endothelial cells in culture appeared to be well in line with their capacity to induce tumor necrosis. Data suggest that direct (synergic) effects on endothelium may contribute to the induction of vascular damage in tumors by (combinations of) the agents. The fact that endothelial cell death is only induced by the combinations and not by the separate agents in vivo, may be a cause of the greater therapeutic activity of the combinations in vivo. The synergy between rTNF and the other agents indicates that the agents act by different mechanisms.

Animals↗

PubMed1989

Popliteal lymph node reactions in mice induced by the drug zimeldine.

The antidepressant drug zimeldine was screened for immune modulating properties using the popliteal lymph node (PLN) assay as a test system in mice. In immunocompetent as well as congenitally athymic nude mice, footpad injection of 1.0 mg zimeldine triggered a bimodal footswelling. A transient oedematous swelling, histologically characterized by mast cell degranulation, was followed by infiltration of polymorphnuclear cells. A dose-dependent PLN enlargement to the agent was observed, which appeared to be more pronounced in immunocompetent mice as compared with athymic nude mice, and in H-2b mice as compared with H-2d mice. After injection of 1.0 mg zimeldine into the footpad of C57BL/10 mice, significant enlargement was already observed by 3 days after injection, was optimal around day 9 and persisted for at least 30 days. Histologically, PLN reactions were characterized by blast transformation of lymphocytes and expansion of paracortical areas prior to germinal center reactions in enlarged follicles. Size of both areas gradually decreased as the medulla filled with plasma cells, 7-30 days after injection. The observed reactions could not be transferred with syngeneic lymph node cells after prior exposition to zimeldine in vivo or in vitro. We conclude that zimeldine induces strong and persistent PLN enlargement, blastogenesis and prominent germinal center reactions. Immunocompetent T-cells are apparently conducive, but not prerequisite to these reactions, which suggests involvement of multiple mechanisms including those mediated by inflammatory reactions in the foot. It is unlikely that the observed enlargement of PLN can be attributed to a direct chemical modification of leukocyte membranes by zimeldine. The protracted nature of the reaction may indicate that zimeldine somehow interferes with inhibitory feedback mechanisms.

Animals↗

PubMed1989

The popliteal lymph node assay in mice to screen for the immune disregulating potential of chemicals--a preliminary study.

Low mol. wt compounds were tested in the popliteal lymph node (PLN) assay to study whether PLN reactivity could be related to the ability of the compounds to induce autoimmune disorders in man. PLN reactions were measured 7 days after a single subcutaneous (s.c.) injection of dissolved compounds in amounts of 0.3-2.0 mg into one hind footpad of mice and assessed as the weight increase of the draining PLN relative to the PLN weight of the untreated contralateral paw. Hydralazine, chlorpromazine, diphenylhydantoin, carbamazepine, phenylbutazone and nitrofurantoin, all being drugs with a documented potential to induce systemic immunological disorders in man, caused marked PLN reactions. False negative PLN responses were observed following injection of procainamide and isoniazid. Among systemic drugs without known potential to induce autoimmune reactions in humans, quinacrine, denzimol and niridazole significantly increased PLN weights, while phenobarbital, levamisole and disulfiram had no effect. Chemicals with a well-known capacity to induce contact dermatitis in man like 2,4-dinitro-1-chlorobenzene, alpha-methylene-gamma-butyrolactone, p-phenylenediamine, 5-nitro-2-furaldehyde semicarbazone, 2-mercapto-benzothiazol and 1,3-dibutyl-2-thiourea caused marked PLN reactions, while the non-sensitizer 2,4-dichloro-1-nitrobenzene failed to do so. It is concluded that the PLN assay as applied in this study may give a rapid first indication of immunomodulating potential of low mol. wt compounds, but it does not discriminate as to the kind of immunomodulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Antitumor effects of endotoxin against solid murine Meth A tumors of different ages. Quantitative histology of the tumors and regional lymph nodes.

Mice with 3-, 6-, 9- and 15-day Meth A tumors in the skin were injected intravenously with endotoxin to study age-dependent induction of tumor necrosis and reactive changes in draining lymph nodes. By 24 h after treatment with endotoxin, macroscopic necrosis was seen in 9-day, and to an even greater extent in 15-day tumors; microscopy showed extensive necrosis in 9-day tumors and some necrosis in 6-day tumors. The necrosis was predominantly coagulative, but the 9- and 15-day tumors showed a rim of hemorrhagic necrosis near the skin with surviving tumor tissue located at the lateral and basal margins. All the tumors showed about equal hyperemia by 4 h and mitotic arrest by 4 and 24 h. Depletion of mast cells, which were most numerous in the 9-day tumors, was seen on the dermal aspects by 24 h. Endotoxin did not change the morphology of the lymph nodes and disseminated tumor cells within 24 h. Endotoxin is known to cure 9-day Meth A tumors, and the extent of the rapid necrosis induced is clearly the crucial factor. Necrosis, however, is not a direct consequence of early hyperemia or mitotic arrest and other factors related to the age and site of the tumor, apparently affect whether or not necrosis ensues.

Animals↗