Differences in the repertoire of the Lewis rat T cell response to self and non-self myelin basic proteins

We have examined the fine specificity of a panel of cloned T cell hybridomas generated from Lewis rats immunized with guinea pig (GP) or Lewis rat myelin basic protein (MBP) to determine the autoimmune T cell repertoire that develops in experimental allergic encephalomyelitis (EAE). This analysis has demonstrated that GP MBP, which was approximately 10-fold more potent for EAE induction than the autologous rat MBP, produced a population in which almost one-fourth of the members responded to GP-unique determinants and displayed no crossreactivity on the self antigen. The remaining majority of GP MBP-induced clones were specific for the 68-88 encephalitogenic determinant and could be subdivided into three groups based on their varying responses to the 68-88 peptide and rat and rabbit MBPs. Surprisingly, one of these groups showed equal reactivity to GP and rat MBPs. In contrast, the clonotype composition of the T cell population induced by rat MBP was quite different. One-half of these clones comprised a single group responding to the 68-88 determinant, reacting equally with GP and rat MBP. All of these responded to the same range of antigen concentrations as their GP-induced counterparts. The remaining half of that population contained a collection of clones that was nearly as encephalitogenic as the 68-88 population after propagation as a short-term T cell line. These clones were specific for at least three distinct antigenic determinants, all displaying extensive cross-species reactivity, and required as little or less rat MBP for maximal stimulation as did the 68-88-reactive clones. We therefore conclude that the T cell repertoire for MBP does include clones with reactivity to both 68-88 and non-68-88 determinants of GP and rat MBPs, and that both MBPs appear to be equally capable of stimulating these clones in vitro. However, the differences in the clonotype composition of the populations induced by immunization with these two antigens suggest that rat and GP MBPs are subject to different immunoregulatory constraints in the animal and may account for the difference in the encephalitogenic potential of these two antigens.

Effect of 15-deoxyspergualin on experimental organ transplantation

DSPG had a definite but relatively feeble immunosuppressive effect in rats undergoing heterotopic heart transplantation and in dogs after renal transplantation. The drug was toxic in both species, although less so in rats. In dogs, synergistic interactions with cyclosporine and steroids were not evident.

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.

Cyclosporine and skin allografts for the treatment of thermal injury. I. Extensive graft survival with low-level long-term administration and prolongation in a rat burn model

The hypothesis tested in the present and accompanying study is that an effective treatment for severe burns involves early excision of necrotic tissue followed by skin allografting and cyclosporine (CsA) immunosuppressive therapy. LEW (RT1) rats served as recipients of thermal injury and/or skin allografts. BN x LEW F1 (LBN, RT1(l+n)) rats served as skin donors. LEW burn recipients received a hot water (90 degrees C for 10 sec) 30% body surface area (BSA) full-thickness burn. As expected, LEW recipients treated with CsA (25 mg/kg/day for 20 days) demonstrated significant graft prolongation compared with controls (P less than 0.005). Skin graft survival was similarly prolonged in LEW recipients undergoing burn injury, primary wound excision, and CsA administration compared with burn-skin allograft controls (P less than 0.001). Mortality was not increased in the thermal injury-CsA-treated recipients compared with burn controls. A final experiment was initiated to investigate how low-level long-term (greater than 100 days) maintenance CsA treatment influenced skin allograft survival for possible future consideration in burn trauma. Recipients receiving skin allografts plus CsA (20 days, 8mg/kg/day, followed by every other day thereafter) did not reject their grafts. However, a possible early sign of rejection (a single small ulcerative lesion) was noted in five of these long-term CsA-treated animals at a mean of 34 +/- 11 (SD) days. The lesion in these animals did not progress any further during CsA administration. Histopathologic study of selected animals removed from the CsA maintenance regimen for greater than 50 days following long-term administration revealed a number of interesting chronic lesions similar to those previously reported in the skin component of composite tissue (limb) allografts following long-term low-level CsA intervention. In conclusion, CsA was very successful in preventing rejection of skin allografts in a rat burn model without apparent adverse effects.

Cyclosporine and skin allografts for the treatment of thermal injury. II. Development of an experimental massive third-degree burn model demonstrating extensive graft survival

We have previously reported the successful treatment and apparent development of skin allograft tolerance in a patient sustaining massive burns, utilizing skin allografts and cyclosporine. We now report the experimental correlate via successful achievement of a 75% body surface area (BSA) scald burn cyclosporine-skin allograft model in Lewis (LEW) rats. Cyclosporine (8 mg/kg/day) was given to the experimental animals daily for the first 20 days and then three times a week thereafter. Two experimental groups were studied: one received standard posttrauma care and the second critical posttrauma care. Controls (n = 22) and experimental groups 1 (n = 28) and 2 (n = 4) had average survival times of 13.8 +/- 12.8 days, 44.2 +/- 132.5 days, and 172.0 +/- 19.4 days, respectively. The allografts on the surviving experimental animals appeared normal and healthy and had nearly perfect hair growth. These results indicate that the model follows the clinical burn wound course, and treatment of massive burns with primary excision, skin allografts, and low doses of cyclosporine could provide immediate and complete functional repair of the burn wound.

Synergy between subtherapeutic doses of cyclosporine and immunologic enhancement in rat recipients of cardiac allografts

We have analyzed the adjunctive effect of subtherapeutic doses of cyclosporine (CsA, 1.5 mg/kg/day x 7 or 14 days) on cardiac allograft survival in actively and passively enhanced rats. This CsA dose, one tenth of the effective dose, when administered after, but not before, transplantation into enhanced hosts produced permanent graft acceptance; cardiac allografts survive c. 25 days in recipients enhanced only and 1 week in untreated animals. Adoptive transfer of spleen T cells of OX8+ or W3/25+ phenotype from long-term (greater than 200 days) graft recipients prolonged donor-specific test graft survival in naive rats (c. 16 days and c. 14 days, respectively, P less than 0.001) and delayed rejection in reconstituted B rats from 7 days to 21-23 days (P less than 0.001). Indeed, both T subsets were separately equally potent and with no overlap responsible for the suppressor activity. The phenotypic profile of the immune cells in the maintenance phase of enhanced or enhanced + CsA-treated recipients was comparable to naive or isografted controls as demonstrated by flow cytometry and immunohistologic studies. Furthermore, the activation status of the graft infiltrate in long-term survivors was similar regardless of the initial immunosuppressive protocol. CsA contributed selectively to the enhancing regimen in the induction phase of unresponsiveness, diminishing the cellularity of graft infiltrate and preventing intragraft T cell activation. These studies stress synergy between subtherapeutic doses of CsA and immunologic active/passive enhancement, 2 immunosuppressive modalities that spare T cells with suppressor capabilities but differ in the inhibition of T helper cell activation.

Transfer of cyclosporine-associated syngeneic graft-versus-host disease by thymocytes. Resemblance to chronic graft-versus-host disease

Syngeneic rat radiation chimeras treated transiently with cyclosporine (CsA) often develop a GVHD-like syndrome after discontinuing the drug. CsA also causes medullary involution and loss of medullary epithelium in the thymus. Chronic graft-versus-host disease (GVHD), a late occurring syndrome following bone marrow transplantation with many features of autoimmune diseases, is thought by many to result from a thymic deficiency leading to a failure to develop specific tolerance for the host. A direct connection between a thymic deficiency and chronic GVHD was tested by transferring thymocytes from CsA-treated syngeneic Lewis chimeras into irradiated Lewis secondary recipients. Nine of 10 of these recipients had evidence of chronic GVHD in skin biopsies taken at 3 weeks posttransplant or in the autopsies at 5 weeks. Changes included characteristic lichen planuslike infiltrates and sclerodermalike changes in the skin, characteristic infiltrates and myositis of the tongue, often chronic hepatitis with bile duct injury, and interstitial and ductal infiltrates in the serous salivary glands. Immunoperoxidase stains of the skin and tongue infiltrates showed a marked predominance of W3/25+:OX8- lymphocytes. The hair follicles had increased expression of Ia antigen. The thymus in the secondary recipient had variable thymocyte reconstitution of the cortex and a mild to marked reduction in the relative size of the medulla. Stains for cytokeratin showed a moderate to marked reduction of cortical epithelium and marked to total loss of the medullary epithelium. These studies demonstrate that the features of post-CsA syngeneic GVHD resembling chronic GVHD result from an abnormal thymic microenvironment. They also provide additional evidence linking a thymus deficiency with chronic GVHD.

A monoclonal antibody against a myelin oligodendrocyte glycoprotein induces relapses and demyelination in central nervous system autoimmune disease

The factors contributing to chronic relapsing inflammatory disease processes of the central nervous system (CNS) and demyelination are poorly understood. In addition to cellular immune reactions, humoral factors such as antibodies might quantitatively or qualitatively influence the disease process. We therefore investigated the effects of administration of a monoclonal antibody specific for a CNS autoantigen on both acute and chronic experimental autoimmune encephalomyelitis (EAE) in mice and rats. This monoclonal antibody, 8-18C5, specific for a myelin/oligodendrocyte glycoprotein, was observed to accelerate clinical and pathologic changes of CNS autoimmune disease. In SJL mice with chronic relapsing EAE, injection of antibody into animals recovering from an attack induced fatal relapses; in Lewis rats, acute EAE was enhanced and associated with a hyperacute inflammatory response with demyelination, a feature not commonly seen in acute EAE. The demonstration that relapses and demyelination can be induced by administration of a white matter-reactive monoclonal antibody offers new possibilities to study processes resulting in CNS damage during autoimmune disease. Furthermore, these findings support the immunopathogenic potential of antibody to myelin components in inflammatory CNS disease processes and, specifically, in causing demyelination.

Importance of immunoglobulin isotype in therapy of experimental autoimmune encephalomyelitis with monoclonal anti-CD4 antibody

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease mediated by CD4+ T cells. Prior studies have established that monoclonal anti-CD4 antibodies can reverse EAE. To determine whether immunoglobulin isotype plays a role in the therapy of EAE with anti-CD4 antibody, an isotype switch variant family of the mouse IgG1 anti-rat CD4 antibody W3/25 was isolated with the fluorescence-activated cell sorter. The IgG1, IgG2b, and IgG2a W3/25 isotype variants all had identical binding capacities for rat CD4+ T cells. Although all three W3/25 isotypes showed some beneficial effects in the amelioration of EAE, the IgG1 and IgG2a W3/25 antibodies were superior to the IgG2b W3/25 in the treatment of EAE. Multiparameter fluorescence-activated cell sorter analysis of T cell subpopulations from treated rats showed that none of the antibodies of the W3/25 isotype switch variant family substantially depleted CD4+ target cells in vivo. These experiments demonstrate that immunoglobulin isotype is important in the monoclonal antibody therapy of autoimmune disease. They indicate that therapy of EAE may be successful without a major depletion of CD4+ lymphocytes. Immunotherapy may be optimized by selecting an appropriate isotype of a monoclonal antibody.

Enumeration of interleukin 2-producing cells from rat spleen

A method for the enumeration of IL2-producing cells from rat spleen has been developed. Rat spleen cells were stimulated with concanavalin A (Con A), washed, then mixed with IL2-dependent cells (3 day Con A blasts) and plated in soft agar. Clusters of IL2-dependent cells formed around IL2-producing cells, giving colonies which were easy to count under a dissecting microscope. All experimental factors influencing development of colonies of IL2-producing cells surrounded by IL2-dependent cells were evaluated and set up. Optimum number of effector cells was 2.5 x 10(5) cells/culture, while optimum number of IL2-dependent cells was 6 x 10(6) cells/culture. Optimum concentration of Con A for IL2 stimulation was 40 micrograms/ml with an optimal stimulation time of 10 hours. Optimum incubation time for development of IL2-producing cell colonies was 5 days. The number of IL2-producing cells by this technique had a good correlation with the level of IL2 in the cell culture fluid (r = 0.885). When colonies were aspirated from agar and stained by Wright stain, a big purple stained cell at the center was surrounded by small cells in almost all colonies examined. All cells from colonies were fluoresed with anti-mouse Thy 1.2-fluorescein conjugate. However, they were negative with anti-mouse Ig-fluorescein conjugate. The number of IL2-producing cells was 816-2080 cells/10(6) of rat spleen cells with mean +/- S.E.M. = 1404 +/- 154/10(6) cells.

Four epitopes on the rat 55-kDa subunit of the interleukin 2 receptor as defined by newly developed mouse anti-rat interleukin 2 receptor monoclonal antibodies

Four new mouse monoclonal antibodies (mAb), ART-38, ART-35, ART-75 and ART-94, directed against the rat interleukin 2 receptor (IL 2R) have been developed. As shown by immunoprecipitation studies they all recognize specifically the 55-kDa subunit of the rat IL 2R. These mAb were compared to three previously characterized mouse mAb directed against the 55-kDa molecule of the rat IL 2R, namely the ART-18, ART-65 and OX-39 mAb. Out of all seven mAb, only ART-18 and OX-39 were found to inhibit the IL 2 binding to activated T cells, while IL 2R inhibited the binding of ART-18 alone. ART-18 was the only mAb found to inhibit the IL 2-dependent proliferation of cells carrying the IL 2R. Scatchard plot analyses showed gross differences in the numbers of mAb-binding sites ranging between 30,000 (ART-65) and 165,000 (ART-75) as well as in their affinities which ranged between 2.5 X 10(-9) M (ART-38) and 8.3 X 10(-10) M (OX-39). Cross inhibition studies revealed that the mAb recognize four different epitopes on the 55-kDa rat IL 2R subunit.

Blood-brain barrier protein recognized by monoclonal antibody

An IgG1 mouse monoclonal antibody produced in response to immunization with rat brain homogenate reacted with endothelial cells in the central and peripheral nervous system. Because antibody reactivity was associated with endothelia that have a selective permeability barrier, the antibody was called anti-endothelial-barrier antigen (anti-EBA). Paraffin sections of Bouins'-fixed rat tissue were used for initial screening and subsequent characterization of antibody reactivity. The antibody was generally unreactive with endothelial cells in other organs and with nonendothelial cells in or outside of the nervous system. Antibody binding was greatly reduced or absent in endothelia of the area postrema and choroid plexus, sites known to possess fenestrated blood vessels. In developing rat brain, anti-EBA binding to some microvessels was seen at 3 days postnatally. Anti-EBA reactivity outside the nervous system occurred in spleen and skin. Patchy reaction with portions of some spleen blood vessels and binding to some cells in the spleen were observed. In the skin, small cells, tentatively identified as Langerhans cells, which participate in Ia presentation, were stained. On immunoblots of rat brain microvessel preparations electrophoresed in Na-DodSO4/polyacrylamide gels, anti-EBA reacted with a protein triplet of Mr 30,000, 25,000, and 23,500 components.

Homing of antigen-specific T cells in the Lewis rat. I. Accumulation of antigen-reactive cells in the perithymic lymph nodes

A permanent ovalbumin-specific T cell line of "helper/inducer" cell phenotype (W 3/13+, W 3/25+, OX 8-) was used to study the homing pattern in normal untreated Lewis rats. After i.v. injection, the migration of these cells was followed directly by using 51Cr- or [14C]thymidine-labeled cells. In addition, I tried to retrieve the cells from different lymphatic tissues by antigen restimulation. I found that most of the radiolabeled cells migrate to the lung, liver, kidney, and spleen. Other lymphoid tissues such as the thymus and the cervical and mesenteric lymph nodes were almost devoid of such cells with one exception: the perithymic lymph nodes (pt-LN). Twenty-four hours after the cell transfer, viable antigen-specific cells could be recovered from these organs. Within 9 days the pt-LN enlarged, the percentage of W 3/13+ and W 3/25+ T lymphocytes was enhanced, and both relatively high spontaneous and antigen-driven responses were measurable in cell cultures of these lymph nodes. All the effects were observed if viable but not irradiated antigen-specific T blasts were transferred. Moreover, after active immunization, antigen-reactive cells appeared to accumulate not only in the draining but also in the pt-LN. In both experimental situations, the adoptive transfer and the in vivo activation of antigen-specific lymphocytes, the pt-LN appear to play an important role in the homing of such cells.

Synthesis and cell surface display of class II determinants by long-term propagated rat T line cells

We have investigated the capacity of the encephalitogenic BS rat T cell line bs 83 and its variant clone bs 83.III.C6 to synthesize and express RT1.B-specific class II molecule subsets defined by monoclonal antibodies (mAb) MRC-OX6 and MRC-OX3. Earlier studies had indicated that mAb MRC-OX6 recognizes three distinct molecular species: an immature oligomeric polypeptide chain complex comprised of the polymorphic subunits alpha, beta and the invariant proteins of the gamma group; a biosynthetic intermediate composed of post-translationally modified alpha, beta and gamma chain (denoted p35) and a fully glycosylated alpha, beta two-chain complex derived from the plasma membrane. MRC-OX3 was shown to recognize a serologically distinct alpha, beta two-chain complex that coexists with the MRC-OX6-specific heterodimer at the cell surface. Here we show that premutant bs 83 cells were unable to synthesize class II molecules of either set. In contrast endogeneous synthesis by mutant cells of MRC-OX6-specific molecules was demonstrated. Unlike control spleen cells variant cells failed to synthesize the mature MRC-OX3-reactive class II subset. Instead a three-polypeptide chain complex comprised of the terminally glycosylated subunits alpha, beta and invariant chain p35 was present at the cell surface. This complex appears to represent the preserved biosynthetic intermediate that failed to release invariant chain p35 upon its transit into the plasma membrane. These latter observations support our notion of gamma chain-induced epitope diversification during post-translational maturation of RT1.B-specific class II molecules.

Therapeutic vaccination against adjuvant arthritis using autoimmune T cells treated with hydrostatic pressure

An ideal treatment for autoimmune diseases would be a nontoxic means of specifically neutralizing the autoreactive lymphocytes responsible for the disease. This goal has been realized in experimental autoimmunity models by immunizing rats or mice against their own autoimmune cells such that the animals generate an immune response specifically repressive to the disease-producing lymphocytes. This maneuver, termed lymphocyte vaccination, was demonstrated to be effective using some, but not all, autoimmune helper T-lymphocyte lines. We now report that T lymphocytes, otherwise incapable of triggering an immune response, can be transformed into effective immunogens by treating the cells in vitro with hydrostatic pressure. Clone A2b, as effector clone that recognized cartilage proteoglycan and caused adjuvant arthritis in Lewis rats, is such a cell. Untreated A2b could not trigger an immune response, but inoculating rats with pressure-treated A2b induced early remission of established adjuvant arthritis as well as resistance to subsequent disease. Specific resistance to arthritis was associated with anti-idiotypic T-cell reactivity to clone A2b and could be transferred from vaccinated rats to naive recipients using donor lymphoid cells. Aggregation of T-lymphocyte membrane components appeared to be important for an immune response because the effects of hydrostatic pressure could be reproduced by treatment of A2b with chemical cross-linkers or with agents disrupting the cytoskeleton. Populations of lymph node cells from antigen-primed rats, when treated with hydrostatic pressure, could also induce suppression of disease. Thus, effective vaccines can be developed without having to isolate the autoimmune T lymphocytes as lines or clones. These results demonstrate that effector T lymphocytes suitably treated may serve as agents for specifically controlling the immune system.

(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.

Long-term survival of skin allografts in rats treated with topical cyclosporine

The use of topical cyclosporine (CsA) was studied in skin allografts from Buffalo to Lewis rats. CsA prepared in olive oil and dimethyl sulfoxide was administered in various dosages topically on allografts. Untreated allografts were rejected in 7.4 +/- 1.1 days but survived for 18.6 +/- 0.9, 29.3 +/- 1.8, or 40.6 +/- 2.2 days after 10, 20, or 28 days of topical CsA treatment (10 mg/rat/day), respectively. Long-term graft survival (greater than 100 days) was seen with continuous CsA treatment at 10 mg/rat/day, 10 mg/rat/2 days, and 5 mg/rat/day, as compared with rejection in 13.1 +/- 2.3 and 8.9 +/- 0.9 days with CsA 10 mg/rat/3 days and 5 mg/rat/2 days, respectively. The therapeutic blood level of CsA ranged from 250 to 500 ng/ml. Most grafts were rejected when CsA blood levels fell below 200 ng/ml. Direct administration of topical CsA onto the allografts resulted in longer survival compared with those applied on the normal recipient skin 6 cm distal to the allografts, with both high and low doses. Locally high concentrations of CsA in allografts may play an important role in prolongation of graft survival. Minimal cell infiltration and loss of hair follicles were the main histological features in long-surviving allografts (greater than 120 days).