Specific heterologous enhancement of immune responses. IV. Specific generation of a thymus-derived enhancing factor.

In short-term cultures of thymocytes from tetanus toxoid-immunized mice, the addition of 1 ng of toxoid generated the release of a soluble factor which was capable of enhancing the immune response to a heterologous immunogen. The addition of supernatants from such cultures to assay cultures of sheep erythrocyte-stimulated normal spleen cells produced a significant augmentation of the hemolytic plaque response. Culture fluid from similar cultures of normal thymocytes or primed thymocytes cultured without the priming antigen were inactive. The enhancing factor was nondialyzable, heat stable (56 degrees C, 30 min), resistant to DNAse and RNAse, but was inactivated by protease. A factor produced by specifically stimulated primed spleen cells had similar characteristics. In toxoid-stimulated, mixed cell cultures containing primed thymocytes or spleen cells and normal spleen cells, tenfold fewer thymocytes than spleen cells were needed to produce a comparable degree of enhancement of the anti-sheep erythrocyte plaque-forming cell response.

Differential roles of Mac-1+ cells, and CD4+ and CD8+ T lymphocytes in primary nonfunction and classic rejection of islet allografts.

The high rate of persistent hyperglycemia, termed primary nonfunction, after islet allotransplantation in C57BL/6 mice recipients of B10.BR strain islets, as compared with B10.BR recipients of C57BL/6 islets, led to a series of experiments to determine whether islet allograft primary nonfunction was attributable to technical aspects of the transplant procedure or whether it was a consequence of alloimmunity. Primary nonfunction was prevented by systemic pharmacologic immunosuppression of the host with cyclosporine. Selective immunodepletion of host CD4+ and CD8+ T lymphocytes significantly extended the time of classic rejection but did not significantly affect the rate of primary nonfunction. However, modulation of macrophages by administration to the host of silica completely abolished primary nonfunction. These observations, in conjunction with the immunohistological findings of intense macrophage infiltration in islet allografts from recipients exhibiting persistent post-transplant hyperglycemia, support the hypothesis that primary nonfunction results from a cell-mediated host-immune response of rapid onset that is dependent on macrophages or macrophage byproducts as the main effectors.

Homograft rejection delayed by treatment of donor tissue in vitro with antilymphocyte serum.

Treatment of rabbit corneal tissue in vitro with pooled rabbit serum delays the onset of corneal homograft rejection in the host. Addition of antilymphocyte serum results in a further significant delay in the onlset of rejection. The mechanisms by which such treatment of donor tissues may modify the antigenic content of the material are discussed.

Structural and functional evolution of jejunal allograft rejection in rats and the ameliorating effects of cyclosporine therapy.

We assessed the structural and functional evolution of small intestinal transplant rejection in a rat model by use of 1-micron section, electron microscopic, and in vitro electrophysiologic techniques to study jejunal mucosa 3, 6, and 9 d posttransplantation. The earliest structural abnormalities detected in jejunal loops transplanted from Lewis X Brown Norway F1 hybrids into Lewis rats occurred within 3 d posttransplantation and consisted of focal endothelial cell injury of the microvasculature and focal injury of crypt epithelial cells. Both alterations were associated with adjacent infiltration of large lymphoid cells, and both markedly progressed and became rather diffuse over the following 6 d. In contrast, villus absorptive cells were not markedly altered in structure until the 9th postoperative day. As compared with host jejuna, allograft jejunal epithelium demonstrated multiple functional abnormalities. Transepithelial resistance declined progressively by days 6 and 9 (both P less than 0.05), although baseline transepithelial spontaneous potential difference was only affected at day 9 (P less than 0.01). Stimulated absorption by allograft jejuna, as assessed by measuring electrical response to mucosal glucose, was not significantly diminished until day 9 (P less than 0.05). In contrast, stimulated secretion assessed by measurement of electrical response to serosal theophylline was diminished by day 6 (P less than .01). These data suggest that the earliest epithelial injury during rejection, as judged both structurally and functionally, occurs in the crypt and is paralleled by endothelial injury at the level of the microvasculature. Thus, the primary targets for rejection are most likely endothelial cells and crypt epithelial cells. In contrast, structural and functional impairment of villus epithelium is detectable only at substantially later times during rejection and are most likely secondary processes related to either ischemia produced by microvascular injury or decreased epithelial regenerative ability secondary to crypt injury. Last, we show that the detrimental structural and functional sequellae of jejunal transplantation across the major histocompatibility complex in this model is strikingly ameliorated with cyclosporine therapy.

Transplantation tolerance.

New experimental protocols for the induction of transplantation tolerance continue to be developed. In the past year, encouraging data have been reported from a clinical trial using a protocol specifically designed to induce tolerance to the histocompatibility antigens of the kidney donor. Progress has also been made in our understanding of the mechanisms responsible for the induction and maintenance of tolerance to alloantigens in vivo; it is becoming increasingly clear that more than one mechanism can be involved, particularly at different phases in the response.

Drug-mediated increase of tumor immunogenicity in vivo for a new approach to experimental cancer immunotherapy.

In vivo treatment of leukemic mice with the antitumor agent 5-(3,3'-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) results in early increase of tumor-associated immunogenicity which is expected to evoke host-versus-graft responses. However, transplantation immunity is severely impaired in DTIC-treated mice due to the immunodepressant activity of the drug. It follows that the DTIC-mediated increase of tumor immunogenicity effect cannot be of therapeutic value in ordinary conditions. In the present report, we describe the results of studies aimed at restoring immunocompetence of DTIC-treated mice by means of adoptive transfer of syngeneic lymphoid cells. Infusion of spleen cells into DTIC-treated mice failed to restore graft responsiveness even in allogeneic tumor-host combinations. However, when DTIC treatment was followed by administration of cytotoxic alkylating agents such as cyclophosphamide (CY) or 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), graft responsiveness was partially restored upon adoptive transfer of syngeneic splenocytes. (BALB/c X DBA/2) F1 (hereafter called CD2F1) mice bearing leukemia L1210 Ha were treated as follows: (a) DTIC for increasing the immunogenicity of the leukemic cells; (b) CY or BCNU; and (c) adoptive transfer of CD2F1 lymphocytes. The results showed that: (a) DTIC alone or DTIC plus spleen cells produced little or no increase in survival times with respect to untreated controls; (b) DTIC plus CY or BCNU increased survival times to a larger extent; and (c) the adoptive transfer of lymphocytes produced marked protection of leukemic mice when the hosts had been pretreated with DTIC plus CY or BCNU but not with CY or BCNU without DTIC. These data may provide a model for exploiting DTIC-induced increase of tumor immunogenicity for immunochemotherapeutic regimens.

Prolongation of chemotherapeutically induced remission of a syneneic murine leukemia by L-2,3,5,6-tetrahydro-6-phenylimidazo[2.1-BETA]thiazole hydrochloride.

L-2,3,5,6-Tetrahydro-6-phenylimidazo[2,1-beta]thiazole hydrochloride (LMS), when used in concert with 1,3-bis(2-chloroethyl)-1-nitrosourea, resulted in a significantly higher percentage of long-term leukemic-free survivors. The additive effect provided by LMS treatment was evident during the immunosuppressed period induced by 1,3-bis(2-chloroethyl)-1-nitrosourea treatment and when tumor load was minimal. Treatment with LMS alone did not appear to possess any significant antitumor effect. The beneficial effect of LMS treatment may be attributable to the immunostimulatory activity reported for this drug. LMS appears to possess characteristics that make it an excellent candidate for use as an immunostimulant in cancer combined modality treatment.

Enhanced response to chemoimmunotherapy and immunoprophylaxis with the use of tumor-associated antigens with a lipophilic agent.

Treating iodoacetamide (IAD)-modified lymphoma cells with the lipophilic agent dimethyldioctadecylammonium bromide (DDA) increased their immunogenicity as evidenced by the increased capacity of syngeneic, vaccinated hosts to reject subsequent implants of the same lymphoma. Under conditions of suboptimal immunization to facilitate comparison, there were 61% survivors among mice challenged with tumor implants after immunization with modified cells and DDA compared to 20% survivors among those immunized in the absence of DDA. The enhanced immune response was dependent on DDA dosage and was most striking when DDA was directly complexed to the IAD-treated cells. DDA was also effective with solubilized tumor antigen and with lymphoma cells not pretreated with IAD, but the latter had to be heat killed to assure that they were nontumorigenic. In therapy experiments BALB/c mice bearing P1798 were treated with methotrexate followed by immunotherapy with IAD-P1798 alone or complexed to DDA. With two and three cycles of therapy, methotrexate alone yielded 5 and 13% survivors, while adding immunotherapy with the DDA complex gave survival rates of 63 and 71%. In the absence of DDA, chemoimmunotherapy with methotrexate and IAD-P1798 gave intermediate results. In the absence of antigen, DDA was ineffective in either immunoprophylaxis or therapy experiments.

Abrogation of tumor rejection by trypan blue.

Trypan blue treatment prevented tumor-specific rejection in three animal model systems. These included the spontaneous rejection of tumors of mice (UVT-2051) and guinea pig (line 1 hepatoma) as well as vaccine-induced rejection of a guinea pig tumor (line 10 hepatoma). Secondary immune reactions to line 10 cell challenges were not abolished by trypan blue treatment. Although trypan blue is a potent inhibitor of macrophage cytotoxicity in vitro, the mechanism by which it inhibited tumor-specific rejection has not been established.

Studies of effects of recombinant human tumor necrosis factor on autochthonous tumor and transplanted normal tissue in mice.

The acute hemorrhagic necrosis of tumor nodules caused by the systemic administration of recombinant human tumor necrosis factor alpha (rhTNF-alpha) has been partially attributed to changes in tumor neovascularity. In this study, the effects of rhTNF-alpha were tested on primary autochthonous sarcomas induced in C57BL/6 mice by 3-methylcholanthrene, on spontaneous mammary tumors in C3H/HEN mammary tumor virus positive mice, and on the rejection of normal tissue transplants at different stages of maturity in C57BL/6 mice. Primary i.m. tumors induced by injection of 3-methylcholanthrene grew slowly over a 3-month period and became acutely necrotic after i.v. injection of rhTNF-alpha (2-6 micrograms). In addition, rhTNF-alpha caused a reduction in tumor area of 24% over 10 days compared to a 43% increase in tumor area in control mice receiving excipient (P2 less than 0.01). Histopathologically, tumors underwent central necrosis with a neutrophilic infiltration as was observed previously for serially transplanted tumors following rhTNF-alpha administration. Spontaneous, virally induced mammary tumors underwent a 11% regression on administration of rhTNF-alpha (4-6 micrograms) compared to a 24% growth in mice receiving excipient (P2 less than 0.05). Normal mice were grafted with syngeneic (C57BL/6) or partially allogeneic (C57BL/10 to C57BL/6) skin and were treated with a single dose of rhTNF-alpha (5-20 micrograms) i.v. at either 5, 10, or 15 days posttransplantation. rhTNF-alpha administration had no effect on the integrity of the skin grafts at any maturation point tested (syngeneic graft survival at 60 days: excipient, 35 of 36 versus 20 micrograms rhTNF-alpha, 35 of 36; allogeneic graft survival: excipient, 46 +/- 8 days versus 20 micrograms rhTNF-alpha, 48 +/- 10 days). In addition, rhTNF-alpha had no effect on the integrity of a syngeneic neonatal s.c. heart graft (graft survival at 60 days, excipient, 35 of 36 versus rhTNF-alpha, 30 of 33). Thus, although rhTNF-alpha administration led to marked necrosis and growth inhibition of vascularized tumor, no effect was observed on vascularized normal tissue transplants. To evaluate possible systemic effects of the tumor bearing state on the maturing neovascularity of normal tissue grafts, the three transplant models were studied in mice bearing a 9-day established MCA-106 s.c. sarcoma. After treatment with rhTNF-alpha (2-6 micrograms), acute necrosis and tumor size reduction was apparent in the s.c. tumors; however, no effect was seen in any of the normal tissue transplants.(ABSTRACT TRUNCATED AT 400 WORDS)

A characterization of the immunosuppressive activity of adriamycin and daunomycin on humoral antibody production and tumor allograft rejection.

The effects of adriamycin (AM) and its analog daunomycin (DM) on immunological responsiveness have been investigated in an effort to elucidate whether a differential interaction of the two drugs with the immune system could play a role in the higher antineoplastic activity of AM. It was found that AM induced a greater reduction in the number of antibody-producing cells after primary stimulation with sheep erythrocytes, whereas DM was more suppressive on the secondary response to the same antigen. Primary reactivity to the T-independent antigen S-III was reduced by AM, whereas DM was ineffective in the same conditions even at high doses. In addition, when a tumor allograft model was investigated, DM was significantly more immunosuppressive than was AM administered at equitoxic doses. In contrast, these agents displayed similar activity in reducing bone marrow stem cells and in inhibiting DNA synthesis in this organ. The possibility that the different immunosuppressive capacity of AM and DM contributes to the greater antitumoral activity of the former is advanced.

Combined treatment with nicotinamide and desferrioxamine prevents islet allograft destruction in NOD mice.

Nonobese diabetic (NOD) mice get spontaneous diabetes with clinical and pathological manifestations similar to those seen in human type I diabetes. NOD mice will destroy transplants of treated allogeneic islet tissue by a recurrence of the disease process that destroyed the original islet tissue. This may be prevented by treatment of the animals with combined desferrioxamine and nicotinamide. Transplanted animals become normoglycemic and remain so for the duration of the treatment. This suggests that oxygen-derived free radicals may be involved in islet damage in spontaneous diabetes.

Reversal of diabetes in outbred mice by islet allotransplantation.

The combination of donor pretreatment with cyclophosphamide, organ culture in 95% O2:5% CO2 for 7-10 days, and short-term immunosuppression of recipients with cyclosporin A (CsA) were necessary to obtain 100% survival of single-cluster BALB/c islet allografts in outbred mice. In vivo and in vitro pretreatment of the donor tissue alone resulted in the acceptance of 45% of the islet allografts in nonimmunosuppressed outbred mice. CsA treatment of recipients alone yielded 40% survival of the untreated allografts. CsA treatment played an important role in maintaining the capacity of islet allografts to function in outbred mice. During CsA treatment, 88% of streptozocin-treated mice showed graft-dependent reversal of diabetes; the remainder showed no evidence of graft function, and CsA treatment failed to prevent acute graft rejection. After withdrawal of CsA immunosuppression, 38% of this total group remained normoglycemic. These findings suggest that modulation of both donor-tissue immunogenicity and recipient responsiveness will be required for successful pancreatic islet transplantation in diabetic humans.

Oxygen free-radical scavengers and immune destruction of murine islets in allograft rejection and multiple low-dose streptozocin-induced insulitis.

We examined the effects of desferrioxamine (DFX), a potent inhibitor of the formation of oxygen-derived hydroxyl radicals, and nicotinamide (NIC), a poly(ADP-ribose) synthetase inhibitor and a weak free-radical scavenger, on two models of immune destruction of murine islets [i.e., allograft rejection and multiple low-dose streptozocin (STZ)-induced insulitis]. Freshly isolated or low-temperature-cultured BALB/cJ islets were transplanted beneath the kidney capsules of C57BL/6J recipients. The recipients were treated with NIC alone (500 mg.kg-1.day-1), DFX alone (4.2 mg/day x 14 days), or NIC + DFX. Only recipients treated with NIC + DFX, receiving cultured islets, showed a mean graft survival time significantly longer than control mice receiving freshly isolated or cultured islets. Control CD-1 mice treated with multiple low doses of STZ developed insulitis and diabetes. Treatment with NIC alone, DFX alone, or NIC + DFX decreased the severity of hyperglycemia relative to the controls. Treatment with DFX alone was more effective than NIC alone or NIC + DFX. Only the group treated with DFX alone had a lower incidence of diabetes (mean plasma glucose level greater than 200 mg/dl) than the controls after 4 wk. Histologically, islets from control mice showed severe insulitis, islet destruction, and absence of stainable insulin, whereas islets from DFX-treated mice showed only mild peri-insulitis and a relative preservation of beta-cell granulation. Our study showed that NIC and DFX partially protect islets from immune destruction in allograft rejection and in low-dose STZ-induced insulitis. Apparently, hydroxyl radicals play important roles in both of these models.

Desferrioxamine treatment prevents chronic islet allograft damage.

BALB/cByJ islet allografts are acutely rejected when transplanted into allogeneic mice (CBA/J). Culture of the tissue for 7 days in 95% O2 before grafting is a suboptimal treatment for the reduction of immunogenicity in this strain combination. Approximately half the animals reject these transplants in a chronic fashion. Chronic islet rejection differs from acute rejection of uncultured allogeneic islets. During chronic rejection, beta cells within the transplanted tissue degranulate but remain intact when the animal returns to the diabetic condition. Acute islet rejection is characterized by the destruction of beta cells that remain heavily granulated as long as they remain intact. We examined the effect of the iron chelating agent, desferrioxamine, on chronic islet allograft damage. Desferrioxamine inhibited chronic islet allograft damage but did not influence the process of rejection of uncultured islet tissue. This effect of desferrioxamine could not be attributed to a direct immunosuppressive effect of this agent.

The effect of cyclosporin-A, low-temperature culture, and anti-Ia antibodies on prevention of rejection of rat islet allografts.

The effect of cyclosporin-A, low-temperature culture, and anti-Ia antibodies on prevention of rejection of rat islet allografts was determined. Wistar-Furth islets were isolated by the collagenase technique and transplanted via the portal vein into diabetic Lewis recipients. Cyclosporin-A (30 mg/kg) injected at 0, 1, and 2 days after transplantation produced a significant prolongation of survival of the islet allografts (MST greater than 35.7 +/- 7.0 days) when hand-picked donor islets were used, whereas only a modest prolongation of survival (14.0 +/- 1.6 days) was obtained using donor islets removed directly from Ficoll gradients. This difference in survival was apparently due to the large number of lymphoid, antigen-presenting cells that were present in the islet fraction removed directly from the Ficoll gradients. Treatment of donor, hand-picked islets with a mixture of cross-reactive anti-Ia antibodies and complement without cyclosporin-A therapy did not prolong the survival of islet allografts (MST, 6.5 +/- 0.4 days versus 7.0 +/- 0.5 days in controls). In contrast, treatment of the donor islets with the mixture of anti-Ia antibodies and complement in conjunction with the 3-day course of cyclosporin-A therapy produced an 83% survival of the islet allografts at 60 days after transplantation. In vitro culture of hand-picked donor islets at 24 degrees C for 7 days and the 3-day course of cyclosporin-A therapy produced a 100% survival of the allografts at 60 days after transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspergillus fumigatus epidural abscess in a renal transplant recipient.

An epidural abscess caused by Aspergillus fumigatus occurred in a recipient of a cadaveric, renal allograft. The patient had persistent back pain and a peripheral neuropathy that involved the lower extremities. Signs of spinal cord compression evolved. No definite portal of entry was found. Diagnosis was made by histologic examination and culture of a biopsy specimen. Therapy, consisting of aggressive surgical debridement, intravenous amphotericin B, and oral flucytosine was unsuccessful in eradicating the organism. At postmortem examination, Aspergillus was identified at the abscess site. To our knowledge, aspergillosis presenting as an epidural abscess in the immunosuppressed, renal transplant recipient has not previously been reported and should be considered in the differential diagnosis of back pain and peripheral neuropathy in such a patient.

The improving prognosis after kidney transplantation. New strategies to overcome immunologic rejection.

For the 70,000 patients with end-stage renal disease in the United States, renal transplantation offers the only hope of full recovery from chronic renal failure. However, transplantation has had only limited use, principally because of the risks of graft rejection and immunosuppression. The last ten years have witnessed striking improvements in the survival of patients and grafts resulting from advances in immunologic management, including restricted use of immunosuppression, better histocompatibility testing, HLA matching, blood transfusions, and new drugs for prevention and reversal of transplant rejection. Kidney transplantation now is safe and effective and should be considered for most young and middle-aged adults.

Autologous marrow recovery and sensitization to non-HLA antigens after HLA-identical marrow transplantation for aplastic anemia.

One hundred seventy-five patients with severe aplastic anemia were treated by high-dose cyclophosphamide and HLA-A, -B, and -D-identical sibling marrow transplants. Thirty-eight patients rejected their grafts. Four of the 38 showed autologous marrow recovery as determined by blood genetic markers. The remarkable feature of one case following autologous marrow recovery was the presence of unidirectional proliferative and cytotoxic responses of circulating host lymphocytes to marrow donor lymphocytes in mixed lymphocyte culture and cell-mediated lympholysis. Presumably these responses were the result of in vivo sensitization to those non-HLA antigens for which donor and recipient differed.

Suppression of genetic resistance to bone marrow grafts and natural killer activity by administration of fat emulsion.

Graft rejection is one of the major obstacles to successful bone marrow transplantation (BMT). If resistance to marrow grafting could be avoided, BMT could be used widely in treatment of hematological and immunological disorders. There has been evidence that natural killer (NK) cells play a major role in genetic resistance to BMT and that macrophages are also involved in genetic resistance. Agents toxic to macrophages such as silica and carrageenan have been found to have a suppressive effect on genetic resistance to BMT. Parenteral fat emulsions are known to accumulate in macrophages and to impair various functions of macrophages and those of the reticuloendothelial system. We show here that the administration of a fat emulsion, Intralipos 20%, to recipient mice can suppress genetic resistance to bone marrow grafts and NK cell activity probably through the impairment of the macrophage function. The administration of the fat emulsion might be a new tactic in conditioning protocols for human BMT in the future.