Relationship between collagen-induced and adjuvant arthritis in the Lewis rat.

Adjuvant arthritis (AA) and type II collagen (CII)-induced arthritis (CIA) in the rat serve as models of chronic human arthritis. Adoptive transfer of AA was observed in 21 of 25 Lewis rats given concanavalin A (Con A)-treated spleen cells prepared from animals immunized with Mycobacterium butyricum in mineral oil (complete Freund's adjuvant, CFA). No arthritic changes were noted in rats given spleen cells obtained from donors that had received incomplete Freund's adjuvant (IFA, 0/22), type I collagen in IFA (CI-IFA, 0/6) or CII-IFA (0/28). Administration of spleen cells from IFA, CI-IFA or CII-IFA-injected animals did not modify the development of CIA when these rats were subsequently challenged with CII-IFA. However, partial protection against induction of AA was provided by the transfer of spleen cells prepared from rats immunized with CII-IFA (6/11) but not by those obtained from rats injected with IFA (1/15) or CI-IFA (0/3). Rats that did not develop clinically evident arthritis following the administration of spleen cells prepared from CFA-injected rats were also resistant to AA induction by CFA. Pre-treatment of rats with a synthetic peptide, corresponding to amino acids 180-188 of the Mycobacterium 65 kD heat shock protein (65 kD HSP), significantly delayed the onset of AA, but not that of CIA. Disease-specific resistance to AA, provided by spleen cells prepared from rats injected with CII-IFA and by pre-treatment with the 65 kD HSP 180-188 peptide, may result from the induction of protective tolerance to arthritogenic epitopes present in the Mycobacterium and CII preparations.

The azaspirane SKF 105685 ameliorates renal allograft rejection in rats.

The azaspirane SKF 105685 (N,N-dimethyl-8, 8-dipropyl-2-azaspiro (4.5) decane-2-propanamine dihydrochloride) has been shown to attenuate or reverse the course of immunologic disease in several animal models, possibly through the induction of nonspecific suppressor activity. To investigate its effects on immune-mediated renal disease, SKF 105685 was administered by gavage to rats with kidney allografts. Six days after transplantation, GFR (inulin clearance, 1.46 +/- 0.27 versus 0.41 +/- 0.15 mL/min per kg; P < 0.005) and RPF (p-aminohippurate clearance, 5.48 +/- 0.98 versus 1.99 +/- 0.72 mL/min per kg; P < 0.01) were significantly higher in SKF 105685-treated rats compared with vehicle-treated control rats. In addition, mononuclear inflammatory cell infiltrates were significantly reduced in SKF 105685-treated animals compared with controls. Treatment also reduced renal production of thromboxane B2 (81 +/- 22 versus 424 +/- 76 pg/min per mg of protein; P < 0.0005), prostaglandin E2 (612 +/- 165 versus 2,059 +/- 351 pg/min per mg of protein; P < 0.005), and 6-keto prostaglandin F1 alpha (217 +/- 56 versus 943 +/- 186 pg/min per mg of protein; P < 0.005), but interleukin-1 beta mRNA levels within kidney allografts were not affected by treatment. Thus, the azaspirane SKF 105685 is a novel immunosuppressive agent that substantially ameliorates renal allograft rejection in the rat. Although the mechanism of action is unknown, the beneficial effects of SKF 105685 in rejection may relate to its ability to induce suppressor activity and/or its effects on eicosanoid production.

Modulation of immune status by a conditioned aversive stimulus: evidence for the involvement of endogenous opioids.

Recent research has shown that presentations of an unconditioned aversive stimulus, such as electric shock, can induce alterations of immune function in rats. Furthermore, it has been demonstrated that an innocuous stimulus paired with an unconditioned aversive stimulus can acquire immunomodulatory properties. Research has suggested that endogenous opioid activity is responsible for the alterations of immune function by unconditioned aversive stimulation. The present study evaluated the effect of administration of opiate receptor antagonists, naltrexone and N-methylnaltrexone, on the immunomodulatory effect of a conditioned stimulus (CS) that had been paired with electric footshock. Naltrexone dose-dependently attenuated the CS-induced suppression of the in vitro proliferative response of splenic lymphocytes to concanavalin A, lipopolysaccharide, and a combination of ionomycin and phorbol myristate acetate. Naltrexone also attenuated the CS-induced reduction in natural-killer cell activity. In contrast, the quaternary form of naltrexone, N-methylnaltrexone, did not significantly attenuate the CS-induced immunomodulatory effects. Collectively, these findings indicate that endogenous opioid activity is involved in CS-induced alterations of immune function. Moreover, the lack of effectiveness of N-methylnaltrexone in attenuating the CS-induced immunomodulatory effect suggests that the opioid receptors involved in the effect are located in the central nervous system.

Suppression of the development of adjuvant arthritis by a conditioned aversive stimulus.

The present study evaluated the effect of a conditioned aversive stimulus (CS) on the development of adjuvant-induced arthritis in Lewis rats. Experiment 1 showed that presentation of a CS, on days 12, 14, and 16 following injection with adjuvant containing mycobacterium tuberculosis, resulted in a pronounced suppression of the development of arthritis as measured by a clinical disease severity rating scale and spleen weight. In contrast, presentation of the CS on days 0, 2, and 4 following injection did not have any effect on the development of arthritis. Experiment 2 showed that the suppression of adjuvant arthritis by exposure to the CS was blocked by administration of propranolol, a nonselective beta-adrenergic receptor antagonist. These results demonstrate that a CS can alter the development of adjuvant-induced arthritis, but the effect is dependent upon the timing of the antigen exposure and the presentation of the CS. Moreover, the present findings suggest that blocking beta-adrenergic receptors during presentations of the CS prevents the suppressive effect of the CS.

Behavioral conditioning prolongs heart allograft survival in rats.

Conditioned immunosuppression using a taste aversion paradigm has been demonstrated in a number of laboratory models but few reports have demonstrated changes in immunity sufficient to be of clinical relevance. The experiments reported here demonstrate that the survival of heart allografts in rats can be prolonged by behaviorally conditioned immunosuppression using cyclosporin A (CsA) as an unconditioned stimulus in taste aversion conditioning. Conditioned animals received saccharin as the conditioned stimulus paired with an injection of CsA at 10 and 6 days prior to transplantation. They were reexposed to saccharin alone 1 day prior to and 3 days after transplantation. On these occasions the conditioned group displayed taste aversion behavior when offered saccharin and a significant prolongation of heart graft survival was observed compared to the conditioned and nonconditioned control groups. These experiments suggest that behaviorally conditioned immunosuppression may have important clinical implications as an adjunct to drug treatments in transplantation medicine.

Effect of FK506 in experimental organ transplantation.

FK506 is the most potent immunosuppressive agent known. Its toxicity is substantial in dogs, minor in rats, and unknown in subhuman primates. In small doses that are nontoxic even in dogs, it can be used in synergistic combination with cyclosporine, steroids, and presumably in other drugs.

(Nva2)-cyclosporine--less potent than cyclosporine A in rats with lung and heart transplants.

The ability of a new cyclosporine (Cs) derivative, (Nva2)-Cs (CsG), to suppress rejection of lung and heart allografts in rats was determined and compared with that of CsA. Left lungs were transplanted orthotopically; hearts were transplanted heterotopically into the abdomen. (Nva2)-Cs was used in three experimental protocols: (1) single or three (Nva2)-Cs injections given to lung-transplanted rats, (2) daily oral (Nva2)-Cs treatment at different doses compared with similar CsA treatments in heart allografted rats, and (3) An 11-day (Nva2)-Cs treatment starting at increasing intervals after transplantation of hearts. (Nva2)-Cs was found to be immunosuppressive, and effective even when the treatment started as late as four days after transplantation. However, (Nva2)-Cs was less effective than CsA in suppressing rejection of lung and heart allografts at low doses. Because (Nva2)-Cs is possibly not nephrotoxic, it might be a useful drug if used in higher doses than CsA or in combination with other immunosuppressive agents.

A comparison of cyclosporine A and Nva2-cyclosporine (cyclosporine G) in a rat renal allograft model.

We compared CsG and CsA in the DA-to-Lewis rat renal allograft model. At equivalent oral doses, plasma radioimmunoassay (RIA) CsG levels were higher than CsA (P less than 0.02). Neither drug prevented rejection at doses of 5 mg/kg/day. CsG-treated rats had a higher rejection rate at doses of 7.5 mg/kg/day (P less than 0.05). Both drugs were equally effective in preventing rejection at doses of 10 mg/kg/day. Neither drug was nephrotoxic at the doses used in this study. CsG is a potent immunosuppressant, and thus a potential clinical successor to CsA. Since CsG and CsA provide equivalent immunosuppression at therapeutic doses, CsG's clinical significance will ultimately depend on its nephrotoxicity in man.

Functional maturation of murine B lymphocyte precursors. II. Analysis of cells required from the bone marrow microenvironment.

The development of mature B cells in cultures of early B cell precursors depends on the presence of a confluent adherent bone marrow (aBM) cell layer. Adherent and sIgM+ cell-depleted bone marrow (BM) from untreated or 5-fluorouracil-pretreated donors or day 12 fetal liver cells were used as precursor cell populations. When adherent cells from thymus or highly enriched BM-derived macrophages were co-cultured with precursor cells, mature B cells were not developed. Similarly, aBM cell layers generated in the presence of hydrocortisone and horse serum were unable to support aBM cell-dependent precursor differentiation, even though cortisone was removed before the addition of precursor cells. In contrast, this type of microenvironment promoted the differentiation of precursor of myeloid cell lineages. Repeated treatment of established aBM cell populations with a monoclonal anti-macrophage antibody (31.3, known to recognize a surface marker on a subset of BM macrophages) and complement abolished the capacity of otherwise functional aBM cells to sustain the development of B cell precursors. Macrophage-depleted aBM cells regained their function after supplementation with highly enriched BM-derived macrophages grown in vitro. Limiting dilution analysis of aBM cells in microcultures containing saturating numbers of early B cell progenitors also suggests the participation of more than one cell type in the BM cell population. In conclusion, differentiation of early B cell progenitors requires macrophages in addition to at least one additional cell type contained in the aBM cell population.

Studies on the immunosuppressive properties of cyclosporin a in rats receiving renal allografts.

The immunosuppressive effects of cyclosporin A were tested in a DA (RT-1a) to Lewis (RT-1(1) rat renal allograft model, which represents a very strong histocompatibility barrier. Dose-response studies established that oral doses of 5 mg/kg/day or higher gave complete suppression of rejection, while oral doses of 2 mg/kg/day or lower were without effect. Intravenous administration of the drug approximately doubled its potency. Time studies showed that the period of administration was also critical, with a 7- or 14-day treatment course with 5 mg/kg/day orally giving prolonged graft survival, while a 4-day course was without effect. Large doses (up to 25 mg/kg/day orally) from day 4 after transplantation did not prolong graft survival, suggesting that cyclosporin A has no effect on an established rejection response. It was found that the lymphocytotoxin response to the graft was markedly suppressed by doses of cyclosporin A which maintained normal graft function, while lower doses had little or no effect on the lymphocytotoxin response. A cell-mediated immunity assay showed a substantial response, but one that was lower in amplitude from that of control animals. Histological study of 7th day allograft biopsies demonstrated essentially normal kidneys, except for a mild mononuclear cell infiltrate, at higher doses of cyclosporin. Lower doses of cyclosporin gave a picture of rejection no different from that seen in untreated controls. The LD50 of cyclosporin was found to lie between 50 and 100 mg/kg/day orally. Even the higher of these doses did not cause nephrotoxicity as determined biochemically and histologically.