Modification of Immune Response by Cinnarizine

Effects of cinnarizine on immune response in mice were investigated. Mice were orally administered with cinnarizine and were immunized with sheep red blood cells (SRBC) intravenously. Numbers of plaque forming cells (PFC) to SRBC in spleen of these mice were assayed and delayed-type hypersensitivity (DTH) response to SRBC was measured. 1) PFC response in immunization with 5 × 10⁶ cells/mouse of SRBC was enhanced by administration of 25 mg/kg of cinnarizine, while the response in immunization with 5 × 10⁸ cells/mouse was suppressed by 25 to 200 mg/kg of cinnarizine. 2) From study on timing of administration, suppression of PFC response by 6.25 to 200 mg/kg of cinnarizine was observed at 24 hr. after the immunization. 3) 12.5 to 200 mg/kg of cinnarizine suppressed polyclonal B cell activation induced by lipopolysaccharide (LPS). 4) Colchicine induced suppressor T cell inactivation was prevented by administration of 50 mg/kg of cinnarizine and it was suggested that cinnarizine may induce suppressor T cells from the study of adoptive cell transfer system. 5) 50 mg/kg of cinnarizine showed the suppression of DTH response in expression phase, but not in induction phase. It was concluded that immune responses in mice were modified by cinnarizine.     

Regulation of delayed-type hypersensitivity. III. Effect of cyclophosphamide on the suppressor cells for delayed-type hypersensitivity to sheep erythrocytes in mice.

A previous study (Eur. J. Immunol. 1977. 7: 714) has shown that mice injected intravenously (i.v.) with 4 x10(9) sheep red blood cells (SRBC) produce cells which suppress delayed-type hypersensitivity (DTH). These suppressor cells are theta-positive, antigen-specific and act via a soluble factor which does not bear immunoglobulin determinants (Eur. J. Immunol. 1978. 8: 168). The present paper demonstrates that these suppressor cells are inhibitable by cyclophosphamide (CY). Mice injected with graded amounts of CY two days prior to SRBC injection, showed maximum augmentation of DTH at 200 mg/kg body weight, a dose which completely suppressed the appearance of splenic plaque-forming cells (PFC) to SRBC. In contrast, lower doses of CY enhanced both DTH and PFC responses. Time course studies showed that CY inhibited the precursors of suppressor cells and had little or no effect on suppressor cells which have already encountered antigens. This was further confirmed by passive transfer studies which showed tha- suppressor cells were inhibited if CY was administered at the same time or 2 days before SRBC injection, but were not affected if CY was given after antigen stimulation. Direct evidence for the effect of CY on suppressor cells was obtained by cell fractination with a Ficoll density gradient. The denser suppressor cell population was absent from the spleens of mice treated with 200 mg/kg of CY 2 days before i.v. injection with 1 x 10(9) SRBC.     

Distinction between suppressors of the delayed-type hypersensitivity and the humoral response to sheep erythrocytes.

Suppressors for both delayed-type hypersensitivity (DTH) and the humoral immune response could be simultaneously induced in the spleens of mice by immunization with a high dose of SRBC. Normal recipient mice of the spleen cells from donors immunized 5 days previously elicited depressed DTH or humoral response when immunized with SRBC. The suppressive activity was found to reside in T not B enriched fraction. Four hundred rad irradiation of the primed spleen cells resulted in complete loss of DTH suppressor activity, but only in some reduction of the suppressor activity for the humoral response. In contrast, hydrocortisone treatment of the donor mice caused no loss of DTH suppressor activity while approximately half of the suppressive activity for anti-SRBC PFC response was lost. Adult thymectomy prevented completely the induction of the DTH suppressor in contrast to little loss of the suppressor activity for the humoral response. DTH suppression was antigen-specific for the induction, but nonspecific for the expression. However the suppression of the humoral response was antigen-specific not only for the induction but also for the expression. In addition, DTH suppressor was capable of suppressing both the induction and expression of DTH while the humoral response was suppressed only in the induction stage by the suppressor.     

Influence of Arecoline on Immune System: II. Suppression of Thymus-Dependent Immune Responses and Parameter of Non-specific Resistance After Short-Term Exposure

Abstract

Arecoline, a major alkaloid of arecanut was screened to explore its modulatory influence on cell-mediated immune response in a murine model system. the in viva and in vitro effects were evaluated at subtoxic concentrations of arecoline. Delayed type hypersensitivity (DTH) reactions to sheep red blood cells (SRBC) were evaluated in male mice. When treated subcutaneously with 20 mg/kg bw (1/5 of LD50) dose of arecoline for 1, 2 or 3 weeks, the DTH reactions were significantly suppressed. At arecoline concentration of 10 mg/kg bw, there was a moderate reduction in DTH response, while no appreciable change was observed at a dosage of 5 mg/kg bw. the effects were not dependent on the duration of treatment. In contrast, treating with arecoline continuously for 4 days following SRBC immunization showed significant suppression in DTH reactions at both 10 and 20 mg/kg bw doses. When treated after 12 h following immunization with 20 mg/kg bw arecoline, significant reduction in DTH reactions were seen. While moderate reduction in response was observed with arecoline dosage of 10 mg/kg bw, there was no alteration in response at the dose level of 5mg/kg bw. Recovery experiments in mice revealed that arecoline mediated effects are of a reversible nature. Arecoline treatment did not appreciably alter the host resistance to endotoxin shock. In vitro experiments revealed both dose-dependent and time-dependent cytotoxic effects of arecoline when spleen cells were incubated with varying concentrations of arecoline. Concomitant exposure of arecoline at concentrations of 10–6–10–4 m with con A, markedly suppressed both 3H-thymidine incorporation and interleukin-2 production of splenic cells. In contrast, concomitant exposure of arecoline with IL-2 did not alter 3H-thymidine incorporation in the IL-2 dependent cytolytic T-lymphocyte line (CTLL), except at the concentration of 10–4 m arecoline. From these studies it is concluded that the dose-dependent suppressive effects of arecoline on DTH response to SRBC and on certain in vitro lymphocyte functions are more clear than the host resistance to endotoxin shock.     

Cyclosporin A prevents suppression of delayed-type hypersensitivity in mice immunized with high-dose sheep erythrocytes.

When administered intraperitoneally to mice 2 days before immunization with a tolerogenic dose (10(9)) of sheep red blood cells (SRBC), cyclosporin A (CsA; 200 mg/kg) strikingly augmented 4-day delayed-type hypersensitivity (DTH) footpad reactions. These enhanced responses were similar in magnitude to those seen in animals sensitized with an immunogenic, low-dose (10(6)) SRBC. The stimulatory effect of CsA was observed over the dose range of 5-200 mg/kg and was obtained in animals given the drug in one injection, up to 7 days before sensitization. The augmentation of DTH was characterized by footpad swelling, intense mononuclear cell infiltration and increased deposition of 125I-fibrinogen within the challenge site. In addition, increased expression of procoagulant activity by spleen cells in response to antigen was observed. Cell transfer experiments showed that the CsA-enhanced DTH could be adoptively transferred to naive recipients. Additional transfers conducted at the time of antigen challenge suggested that, under the conditions described, CsA inhibited the action of a population of suppressor cells normally effective during DTH reactions.     

Influence of Arecoline on Immune System: III. Suppression of B Cell-Mediated Immune Response in Mice After Short-Term Exposure

Abstract

Arecoline, a major alkaloid of arecanut was examined to explore its modulatory influence on B cell-mediated immune response in a murine model system. The in vivo and in vitro effects were evaluated at sub-toxic concentrations of arecoline. The number of primary antibody forming cells (AFC) and hemagglutinating and hemolysis antibody titers to Sheep Red Blood Cells (SRBC) were evaluated in male mice. Arecoline exposure for a week invoked dose-dependent effect on primary antibody forming cells to SRBC with a maximum reduction at the dosage of 20 mg/kg bw, a moderate reduction at 10 mg/kg bw and no effect at 5 mg/kg bw dose level. HA and HL antibody titers to SRBC were suppressed markedly at arecoline dosage of 20 mg/kg bw and moderately at a dose of 10 mg/kg bw, given daily for 1, 2 or 3 weeks. The inhibitory effect of arecoline was not dependent on the duration of treatment. Like the primary antibody response, the secondary HA and HL antibody titers were also decreased after arecoline exposure. The administration of arecoline dosages 10 and 20 mg/kg bw daily for 4 days following SRBC immunization also, exerted dose-dependent suppression of primary antibody response. Similarly, when treated after 12 h following immunization, significant reduction in response was observed with arecoline dosage of 20 mg/kg bw. While moderate suppression of antibody response was noticed at the dose level of 10 mg/kg bw, there was no alteration in response at a dosage of 5 mg/kg bw. In contrast, arecoline dosages 5, 10 or 20 mg/kg bw given after 1, 2 or 4 days following immunization did not alter the HA and HL antibody titers to SRBC. Recovery experiments in mice revealed that arecoline-mediated suppression of antibody response is of a reversible nature. Concomitant exposure of arecoline at the concentrations of 10^?5 – 10^?4 M with PWM suppressed ³H-thymidine incorporation of splenic cells in vitro. Taken together, the findings reported in this paper suggest that the intensity of arecoline-mediated suppression of antibody response to SRBC and PWM-induced splenic cell proliferation is dependent upon the dosage and the mode of treatment.     

Effect of 1-thiocarbamoyl-2-imidazolidinone on the generation of plaque forming cell responses

Although 1-thiocarbamoyl-2-imidazolidinone (TCI) is a highly potent modulator of cellular immunity, its effects on humoral immunity have not been investigated. Given orally to mice prior to immunization with sheep red blood cells (SRBC), low TCI doses (10(-14) to 10(-10) g/kg) suppressed primary plaque forming cell (PFC) responses of spleen cells by 50-75%. TCI effects in vivo were dependent on drug dose, antigen dose and time of drug administration relative to immunization. The kinetics of this response were not appreciably altered by TCI. Higher TCI doses, immunization with higher levels of SRBC than required to produce a maximal response or administration of TCI later than 48 hours after immunization resulted in drug effects ranging from slight suppression to mild enhancement of the primary PFC response. TCI given in vivo enhanced primary PFC responses to the T-independent antigen DNP-Ficoll by greater than 700%+. TCI given before a primary immunization suppressed a secondary PFC response to SRBC elicited 28 days later. However, when TCI was given 24 h prior to a secondary immunization, doses greater than 10(-5) g/kg were necessary to suppress the PFC response. The effect of TCI on in vitro immunized spleen cell cultures was similar to that found for in vivo immunized mice. TCI at concentrations up to 10(-1) g/l did not cause a loss of lymphocyte viability or inhibit plaque production by antibody producing cells. Effects of TCI on PFC responses in vitro were reversible if cells briefly exposed to an optimal concentration of drug were washed extensively prior to immunization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Modulation of Primary Antibody Response by Protein a in Tumor Bearing Mice

Abstract

Protein A (PA) is a cell wall glycoprotein of Staphylococcus aureus Cowan I, which possess a number of immunomodulatory and antitumor properties. We have previously shown that PA suppresses the anti-sheep erythrocyte primary antibody response in normal mice. The present investigation evaluates the effect of protein A on the anti-sheep erythrocyte primary antibody response in tumor-bearing mice. The primary antibody response in tumor-bearing mice immunized with sheep red blood cells (SRBC) was suppressed by the intraperitoneal administration of PA in a dose-dependent fashion. The plaque forming cell (PFC) assay was used to assess this response. Maximum suppression of the PFC response was observed at 12 μg PA/animal (p<0.001) and could be observed at doses as low as 1 μg PA/animal (p<0.01). The amount of suppression was proportional to the number of PA doses administered. In addition this effect was critically dependent on the timing of PA administration. PA showed no significant effect on PFC when injected after immunization, but it produced pronounced suppression when injected prior to the immunization with SRBC. Maximum suppression of the PFC response was observed when PA was administered one day before the antigen challenge. PA also reduced splenic localization of ⁵¹Cr labeled SRBC to 42% (p<0.01). The altered localization of antigen in spleen may be responsible for reduced PFC response in tumor-bearing mice. Depletion of B-lymphocyte is reported to exhibit tumor inhibition. Therefore, we propose that the suppression of the primary antibody response by PA helps in tumor regression by reducing the soluble immunosuppressive immune complexes.     

Modulation of the immune responses against SRBC after oestriol treatment in mice.

Delayed-type hypersensitivity (DTH), primary direct and indirect PFC, memory antibody response and suppressor cell induction against sheep red blood cells (SRBC) have been examined in oestriol (E3) pretreated mice. The results showed that DTH and primary direct and indirect PFC responses were suppressed by E3 treatment. These suppressive effects could, however, be overcome when oestrogenized mice were given supra-optimal doses of SRBC for each response. On the other hand, the memory antibody response was markedly enhanced when E3 was given prior to the primary antigen stimulation. Induction of the suppressor cells for the antibody response seemed not to be affected by E3 treatment, but the characterization of the suppressor cells revealed that those obtained from E3 treated mice were surface immunoglobulin positive (sIg+) cells whereas those from control mice were not. These results were discussed in terms of the altered antigen distribution due to the activated phagocytic activity of the reticuloendothelial system (RES) after E3 treatment.     

Potentiation of immune responses in mice by a new inosine derivative--methyl inosine monophosphate (MIMP).

Inosine 5'-methyl monophosphate (MIMP) is a new immunomodulator designed to improve upon the activity of other thymomimetic purines. In Balb/c mice, MIMP was assessed for toxicity and activity on immune responses. The lethal dose for half the mice (LD50) exceeded 500 mg/kg of body weight by both the parenteral and oral routes. At doses of 1-100 mg/kg, the mice showed no visible untoward effects. The antibody response of splenocytes to sheep erythrocytes (SRBC) was measured by IgM plaque-forming cells (PFC) in soft agar under optimal conditions of immunization and challenge. MIMP (1-100 mg/kg) was given by both the intraperitoneal and oral routes (gavage) at the time of SRBC injection and 4 days thereafter. The PFC response was found to be significantly augmented. The maximum effect (approximately 2x) was observed at 50 and 100 mg/kg, via intraperitoneal (i.p.) and oral routes, respectively. Increases (maximally 1.5x) in the responses of splenic lymphocytes to mitogen stimulation with phytohemagglutinin (PHA) and concanavalin A (Con A) were observed under similar conditions of MIMP treatment. SRBC-induced delayed-hypersensitivity (DTH) was also measured under optimal conditions. By both i.p. and oral routes, enhancement of DTH response was produced by the lower doses of MIMP (0.01-1 mg/kg). Again, a second peak of optimum stimulation of DTH response was produced by 50 mg/kg of MIMP when administered by both routes. The effect was observed mainly on the sensitization rather than on the expression phase. MIMP qualifies as an effective immunopotentiator in normal mice.     

Suppressor activity of spleen cells in drug-induced immunologic tolerance

Tolerance to sheep's red blood cells (SRBC) was induced in (CBA×C57BL/6)F₁ mice by a single intraperitoneal injection of 6×10⁹ SRBC followed by injection of 100–200 mg/kg cyclophosphamide 44–46 h later. Spleen cells of tolerant mice, obtained at various times (12–26 days) after induction of tolerance, when injected into intact syngeneic recipients, did not depress their immune response to SRBC. Unlike intact mice, tolerant mice were unable to produce suppressor cells after a single immunization with SRBC. Only if three additional injections of large doses (6×10⁹) of SRBC were given to the tolerant mice did their spleen cells acquire the ability to inhibit the immune response on injection into normal mice. It is postulated that the absence of suppressor cells on induction of immunologic tolerance by means of cyclophosphamide is due to clonal elimination. Suppressor cells may arise in tolerant animals under the influence of intensive antigenic stimulation, leading to deepening of the state of tolerance as a result of additional injections of SRBC.Laboratory of Immunogenetics, Institute of Medical Genetics, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Zhukov-Verezhnikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 11, pp. 558–560, November, 1978.     

Effect of Mechlorethamine on SRBC-Induced Secondary Antibody Response in Mice

Abstract

The effect of low-dose mechlorethamine (5μg/kg) on secondary humoral response to sheep red blood cells (SRBC), depending on time of exposure to the drug in relation to priming and challenge was studied in Balb/c mice. It was found that mechlorethamine in a dose of 5 μg/kg stimulated primary humoral response to SRBC resulting in the increased number of the plaque forming cells (PFC) and hemagglutinin titre (19S + 7S). However, this effect waned 10 days after immunization. On the other hand, the same mechlorethamine dose potentiated secondary humoral response to SRBC and increased the number of PFC and anti-SRBC hemagglutinin titres (notably 7S), which was due to the challenging antigenic stimulus. In each immunization, mechlorethamine administration prolonged the potentiating effect of the drug on anti-SRBC hemagglutinin titre. When mechlorethamine was administered to the mice only after priming, the number of PFC increased, but anti-SRBC hemagglutinin titre (7S) remained unchanged. This was likely due to the fact that mechlorethamine administered after priming increases the number of long-lived lymphocytes B, which in turn affect secondary humoral response.     

Influence of Arecoline on Immune System: II. Suppression of Thymus-Dependent Immune Responses and Parameter of Non-specific Resistance After Short-Term Exposure

Arecoline, a major alkaloid of arecanut was screened to explore its modulatory influence on cell-mediated immune response in a murine model system. the in viva and in vitro effects were evaluated at subtoxic concentrations of arecoline. Delayed type hypersensitivity (DTH) reactions to sheep red blood cells (SRBC) were evaluated in male mice. When treated subcutaneously with 20 mg/kg bw (1/5 of LD50) dose of arecoline for 1, 2 or 3 weeks, the DTH reactions were significantly suppressed. At arecoline concentration of 10 mg/kg bw, there was a moderate reduction in DTH response, while no appreciable change was observed at a dosage of 5 mg/kg bw. the effects were not dependent on the duration of treatment. In contrast, treating with arecoline continuously for 4 days following SRBC immunization showed significant suppression in DTH reactions at both 10 and 20 mg/kg bw doses. When treated after 12 h following immunization with 20 mg/kg bw arecoline, significant reduction in DTH reactions were seen. While moderate reduction in response was observed with arecoline dosage of 10 mg/kg bw, there was no alteration in response at the dose level of 5mg/kg bw. Recovery experiments in mice revealed that arecoline mediated effects are of a reversible nature. Arecoline treatment did not appreciably alter the host resistance to endotoxin shock. In vitro experiments revealed both dose-dependent and time-dependent cytotoxic effects of arecoline when spleen cells were incubated with varying concentrations of arecoline. Concomitant exposure of arecoline at concentrations of 10-6-10-4 m with con A, markedly suppressed both 3H-thymidine incorporation and interleukin-2 production of splenic cells. In contrast, concomitant exposure of arecoline with IL-2 did not alter 3H-thymidine incorporation in the IL-2 dependent cytolytic T-lymphocyte line (CTLL), except at the concentration of 10-4 m arecoline. From these studies it is concluded that the dose-dependent suppressive effects of arecoline on DTH response to SRBC and on certain in vitro lymphocyte functions are more clear than the host resistance to endotoxin shock.     

Regulation of immune response to SRBC: suppressor cell activity induced by soluble fraction of antigen.

Water soluble fraction (SF) of SRBC was obtained by hypotonic lysis and ultracentrifugation. SF was found to induce very weak SRBC-specific antibody response in mice. Pretreatment with SF accelerated direct PFC response to SRBC and accelerated and suppressed indirect PFC response. Spleen cells from mice treated with SF exhibited enhanced response to SRBC after transfer in irradiated recipients. The transfer of spleen cells from mice treated with SF to normal non-irradiated mice markedly suppressed the recipients' PFC responses to SRBC. The observed suppressive effect is interpreted as a consequence of suppressor cell activity.     

Differential Inhibition by Azathioprine and 6-Mercaptopurine of Specific Suppressor T Cell Generation in Mice

Doses of 100 mg/kg/day and 55 mg/kg/day of azathioprine (AZ) and 6-mercaptopurine (6-MP), respectively, significantly suppressed anti sheep red blood cell (SRBC) responses in CBA mice, assayed by the complement-dependent cellular cytotoxicity (CDCC) test and by serum titration. Four injections of similar doses of the agents were given to donors of carrier-specific suppressor T cells, generated by two immunizations with SRBC, and transferred to syngeneic recipients sensitized with the TNP hapten on SRBC carrier. Anti-TNP response of the recipients was assayed by the CDCC, using TNP-coated EL4 target cells. Whereas 6-MP, given after or before the second immunization of the donors with carrier SRBC, caused abrogation of suppressor cell activity, equimolar doses of AZ were less inhibitory to suppressor cell generation.     

Demonstration of T15 idiotype-positive effector and suppressor T cells for phosphorylcholine-specific delayed-type hypersensitivity response in CBA/N or (CBA/N X BALB/c)F1 male mice

Subcutaneous immunization of CBA/N or (CBA/N x BALB/c)F₁ (NBF₁) male mice, which were defective in phosphorylcholine (PC)-specific humoral antibody response, with PC-conjugated syngeneic spleen cells induced a PC-specific delayed-type hypersensitivity (DTH) response, while intravenous administration of the same cells induced PC-specific suppressor T cells for the DTH response. Treatment of PC-specific effector or suppressor T cells for the DTH response induced in NBF₁ male mice with anti-T15 idiotypic antibody inactivated effector or suppressor functions of these T cells implying that PC-specific T cells in NBF₁ mice expressed T15 idiotypic determinants on their surface. Enrichment of PC-specific suppressor T cells was also shown by employing anti-T15 antibody-coated dishes.     

Antibody formation in mouse bone marrow: III. Effects of route of priming and antigen dose

The influence of the route of priming and the dose of sheep red blood cells (SRBC) on the IgM-, IgG- and IgA-plaque-forming cell (PFC) activity in mouse bone marrow during the secondary response to SRBC was studied. After intraperitoneal and subcutaneous priming the number of IgM-, IgG- and IgA-PFC during the secondary response increased with the number of SRBC used for priming. After intravenous (i.v.) priming the priming dose—secondary response relationship was found to be an optimum curve for IgM-PFC as well as for IgG- and IgA-PFC. A peak secondary response in the bone marrow was found after priming with 10⁷ and with 10⁸ SRBC i.v.

The appearance of IgG- and IgA-memory cells in the bone marrow after i.v. immunization with SRBC was shown to be dependent on the priming dose: the appearance of IgG-memory cells required a higher dose of SRBC than the appearance of IgM-memory cells, and the appearance of IgA-memory cells required even more antigen.

The effect of the booster dose upon the PFC activity was studied in mice primed with 10⁷ SRBC i.v. and boosted with 10⁴, 10⁶, or 10⁹ SRBC i.v. 2 months later. IgM-PFC as well as IgG- and IgA-PFC were present in spleen and bone marrow at each booster dose tested. In each group of mice the PFC activity in the bone marrow rose to a level which surpassed the level in the other lymphoid organs between the 7th and 10th day after the booster injection. Thus, independently of the booster dose, mouse bone marrow is the major source of PFC during the late phase of the secondary response to SRBC. Mice boosted with 10⁹ SRBC i.v. showed a prolonged presence of IgM-, IgG- and IgA-PFC in the thymus. Light and electron microscopic studies revealed the presence of plasma cells and macrophages studded with phagocytosed material in the thymic medulla of these mice, thus providing evidence for a real PFC response within the thymus. A thymic PFC response was absent in mice boosted with either 10⁴ or 10⁶ SRBC i.v. Therefore the thymic PFC activity during the secondary response to SRBC does depend on the booster dose.

     

Immunomodulatory Activity of Curcumin

Curcumin, an active ingredient present in Curcuma longa, was analysed for the immunomodulatory activity in Balb/c mice. Curcumin administration was found to increase the total WBC count (15, 290) significantly on the 12th day Group of animals treated with vehicle alone showed results similar to that of normal animal (10, 130 on 12th day). Curcumin increased the circulating antibody titre (512) against SRBC. Curcumin administration increased the plaque forming cells (PFC) in the spleen and the maximum number of PFC was observed on the 6th day (1, 130 PFC/10⁶ spleen cells) after immunization with SRBC. Bone marrow cellularity (16.9×10⁶ cells/femur) and α-esterase positive cells (1, 622/4000 cells) were also enhanced by Curcumin administration. A significant increase in macrophage phagocytic activity was also observed in Curcumin treated animals (P<0.001). These results indicate the immunostimulatory activity of Curcumin.     

Enhancement of the Arthus reaction and suppression of delayed type hypersensitivity (DTH) by pluronic F-68, a detergent frequently used to prepare perfluorocarbon emulsions

The effect of a 20% w/v RM101 (perfluorobutyltetrahydrofuran) emulsion containing 5% w/v of the detergent Pluronic F-68 or 5% w/v Pluronic F-68 given alone on the Arthus reaction and on delayed type hypersensitivity (DTH) were evaluated in female A/J mice. The test substances were administered i.v. at 1% body weight at 0,4,7,14 and 28 days prior to the i.p. immunization with 10(7) sheep red blood cells (SRBC). The increase in footpad swelling at 4 h (Arthus reaction) and at 24 h (DTH) after elicitation with the s.c. administration of 10(8) SRBC into the left footpad was used to assess immune competence. Pluronic F-68 given alone enhanced the Arthus reaction only when administered on day 0 of immunization. Pluronic F-68 given alone, as well as the perfluorocarbon emulsion containing Pluronic F-68, suppressed the 24 h DTH for as long as 4 days prior to immunization. Nonemulsified perfluorocarbon, on the other hand, had no effect on either the Arthus reaction or on DTH. The immunostimulatory agent, levamisole, administered (10 mg/kg i.p.) 1.5-2 h prior to immunization with SRBC counteracted both the Arthus reaction and the DTH response produced by Pluronic F-68. The present data clearly demonstrate that the changes in Arthus reaction and the DTH response are due to the Pluronic F-68 used to emulsify the RM101 perfluorocarbon; the changes induced by the detergent in these two immune parameters probably involve separate mechanisms.     

Effect of Benzodiazepine Derivatives: I. Augmentation of T Cell-Dependent Antibody Response by Diazepam in Mouse Spleen Cells

Abstract

Oral administration of diazepam at doses of 5–10 mg/kg to restraint-stressed mice resulted in almost complete recovery in the stress-induced suppression of the antibody response to sheep red blood cell (SRBC). Noreover, this compound restored the suppression of antibody response to SRBC in cyclophosphamide-treated mice. Diazepam treatment also enhanced the antibody response against SRBC in normal mice only when the animals were immunized with the reduced amount of antigen. It was demonstrated that antigen specific helper T cell activity was promoted by diazepam administration in mice. Addition of diazepam augmented the in vitro anti-SRBC hemolytic plaque-forming cell (PFC) response in mouse splenocytes without altering kinetics of the response. However, the enhancing effect was observed only when the drug was added to the medium at the culture initiation. On the other hand, antibody response to T cell-independent antigens such as trinftrophenylated (TNP)-Ficoll and TNP-lipopolysaccharide were not enhanced by diazepam. Concanavalin A or LPS-induced ³H-thymidine uptake into splenocytes were not stimulated by diazepam. These results suggest that diazepam promotes the antibody response through stimulating helper T cell functions.