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Biomedical subjects

C B Carpenter

Publications and source records attributed to C B Carpenter.

At least 19 recordsLinked to original sources
PubMed1992

Induction of immunity and oral tolerance with polymorphic class II major histocompatibility complex allopeptides in the rat.

We studied the immunogenicity and tolerogenicity of class II major histocompatibility complex (MHC) allopeptides in the rat. Inbred LEW (RT1l) rats, used as responders, were immunized in the foot pad with a mixture of eight synthetic class II MHC allopeptides emulsified in complete Freund's adjuvant. These sequences represent the full-length second domain of RT1.Bu and RT1.Du (WF) beta chains. In vitro, responder lymphocytes harvested from popliteal and inguinal lymph nodes of immunized animals exhibited significant proliferation to the MHC allopeptide mixture. In addition, these responder lymphocytes had significantly increased proliferation to allogeneic WF (RT1u) stimulator cells, when compared to naive controls in the standard one-way mixed lymphocyte response. In vivo, peptide-immunized LEW animals were challenged in the ear 2 weeks after immunization with the allopeptide mixture, the individual allopeptide sequences, or allogeneic WF splenocytes. When compared to controls, these animals had significant delayed-type hypersensitivity responses to the allopeptide mixture, to the beta-pleated sheet allopeptide sequences, and to allogeneic WF splenocytes but not to the alpha-helix allopeptide sequences, to syngeneic LEW splenocytes, or to third party allogeneic BN splenocytes. Oral administration of the allopeptide mixture to LEW responder rats daily for 5 days before immunization effected significant reduction of delayed-type hypersensitivity responses both to the allopeptide mixture and to allogeneic splenocytes. This reduction was antigen-specific, since there was no reduction of delayed-type hypersensitivity responses to mycobacterium tuberculosis. These data demonstrate that lymphocytes from animals immunized with polymorphic class II MHC allopeptides can recognize and proliferate to the same amino acid sequences on allogeneic cell surface MHC molecules. In addition, oral administration of these peptides down-regulates the systemic cell-mediated immune response in a specific fashion. Synthetic MHC allopeptides should allow the study of alloimmunity in vivo, including induction of immune tolerance.

Amino Acid Sequence↗
PubMed1992

Down-regulation of the immune response to histocompatibility antigens and prevention of sensitization by skin allografts by orally administered alloantigen.

The effects of oral administration of major histocompatibility antigens on the alloimmune response have not been investigated. Lymphocytes from inbred LEW (RT1u) rats that were pre-fed allogeneic WF (RT1l) splenocytes exhibited significant antigen specific reduction of the mixed lymphocyte response in vitro and delayed-type hypersensitivity response in vivo, when compared with unfed controls. In an accelerated allograft rejection model, LEW rats were presensitized with BN (RT1n) skin allografts 7 days before challenging them with (LEW x BN)F1 or BN vascularized cardiac allografts. While sensitized control animals hyperacutely reject their cardiac allografts within 2 days, animals prefed with BN splenocytes maintained cardiac allograft survival to 7 days, a time similar to that observed in unsensitized control recipients. This phenomenon was antigen-specific, as third-party WF grafts were rejected within 2 days. Immunohistologic examination of cardiac allografts harvested on day 2 from the fed animals had markedly reduced deposition of IgG, IgM, C3, and fibrin. In addition, there were significantly fewer cellular infiltrates of total white blood cells, neutrophils, macrophages, T cells, IL-2 receptor-positive T cells, and mononuclear cells with positive staining for the activation cytokines IL-2 and IFN-g. On day 6 posttransplant, the grafts from fed animals showed immunohistologic changes typical of acute cellular rejection usually seen in unsensitized rejecting controls. Feeding allogeneic splenocytes prevents sensitization by skin grafts and transforms accelerated rejection of vascularized cardiac allografts to an acute form typical of unsensitized recipients. Oral administration of alloantigen provides a novel approach to down-regulate the specific systemic alloimmune response against histocompatibility antigens.

Administration, Oral↗
PubMed1991

Ten-year experience with cyclosporine as primary immunosuppression in recipients of renal allografts.

Cyclosporine has been used as primary immunosuppression in renal allograft recipients in our unit for the past decade. The overall clinical experience and long-term effects of the agent are reviewed. There were 461 consecutive recipients of kidney grafts; 379 received grafts from cadaver donors (CAD) and 82 from living related donors (LRD). Four separate clinical protocols were used sequentially using progressively decreasing doses of CyA; azathioprine was added in group 4 recipients of LRD grafts, and in patients receiving secondary CAD grafts (group 5). The patient mortality rate was less than 5%, with sepsis being the prime contributor. The majority of kidney grafts were lost within the first 2 months after operation; those that never functioned were found almost invariably to have been irreversibly rejected. During the subsequent years of follow-up, attrition of CAD grafts was significantly greater than LRD grafts. In contrast, the attrition rate of primary and secondary CAD grafts was the same after the first 3 months, emphasizing the importance of early immunologic graft destruction. Primary nonfunction occurred in 49% of CAD kidneys and 17% of LRD grafts; however 71% of initially nonfunctioning LRD grafts never functioned at all compared to 34% of CAD grafts, the majority of such organs undergoing fulminate rejection. Individual graft loss after 1 year was almost inevitably due to chronic rejection; there were no differences in long-term allograft function among the treatment groups. Although CyA has improved overall results of kidney transplantation, chronic rejection remains a major unresolved problem.

Adult↗
PubMed1991

A randomized prospective trial of anti-Tac monoclonal antibody in human renal transplantation.

Patient entry is now complete in a prospective trial of anti-Tac, a murine IgG2a monoclonal antibody directed against the p55 chain of the human IL-2 receptor, for the prevention of renal allograft rejection. Recipients of primary cadaver allografts were randomized to receive either anti-Tac (20 mg q.d. x 10 days beginning POD 1) plus low-dose CsA (4 mg/kg/day), azathioprine (2 mg/kg/day), and prednisone (30 mg q.d.), or conventional triple therapy with CsA (8 mg/kg/day), azathioprine, and prednisone. Forty patients were entered in each group, with current followup from 6 to 26 months. The results show a significant reduction in early rejection episodes in the anti-Tac-treated patients. During the 10-day treatment, 5 of 40 anti-Tac patients had rejection episodes, compared with 21 of 40 control patients (P less than 0.001). Anti-Tac significantly delayed the time to the first rejection (12.5 +/- 6.3 vs. 7.6 +/- 6.7 days) (P less than 0.05). Despite these effects, there were no differences in either actual or actuarial graft or patient survival between the two groups. Pneumonia, primarily CMV, developed in 5 treated and 4 control patients. In patients with functioning grafts mean serum creatinine at 3 months was 1.8 +/- 0.7 in the anti-Tac group and 2.0 +/- 0.8 in the control group (P = NS); at 12 months the values were 2.3 +/- 1.5 and 1.8 +/- 0.5, respectively (P = NS). The peak expression of IL-2 receptors on circulating T-cells was significantly lower in anti-Tac patients (15.1 +/- 3.6%) than in controls (21.9 +/- 4.5%) (P less than 0.05). Seven of 10 patients tested to date developed antimouse immunoglobulin antibodies, with antiidiotype shown in 6. These antibodies do not preclude subsequent treatment with OKT3. Five patients in this and previous anti-Tac protocols have received OKT3 for acute rejection despite known pretreatment antimouse antibodies, with resolution of rejection in all cases.

Adolescent↗
PubMed1990

Evidence that monoclonal antibodies against the 55kD subunit of the rat IL-2 receptor do not inhibit the development of suppressor cells generated in mixed lymphocyte culture.

Although the ability of Ts to prevent allograft rejection has been well established, their intrinsic characteristics and dependence upon lymphokines remain poorly defined. The cells from unmodified LEWxBN bulk 5-day rat MLR inhibit both proliferation in test MLR and generation of CTL, as well as prolonging the survival of donor-specific test cardiac allografts following adoptive transfer. We have examined the effects of a panel of mAb directed against functionally distinct epitopes on the p55 subunit of rat IL-2R on the generation and in vitro/in vivo activity of MLR-generated Ts. ART-18 (which blocks IL-2-dependent T cell growth) was the only mAb from the panel that profoundly suppressed alloreactive T cell proliferation in primary MLR (47.5%). However, the generation of Ts was never affected by any mAb (% suppression in test MLR = 40-60%). Neither ART-18 nor ART-65 (which does not affect T cell proliferation) interfered with the efficacy of Ts to inhibit CTL generation in fresh bulk MLR. Adoptive transfer of cells (3-10 x 10(6] from ART-18 or ART-65-modulated MLR into naive LEW rats prolonged (LEW x BN)F1 test cardiac allograft survival to 11-13 days (P less than 0.05 as compared with acutely rejecting hosts). All in vitro and in vivo effects exerted by MLR-generated cells were antigen-specific. In unmodified MLR, Ts were IL-2R+ (ca. 50% of total blasts), as shown by cell separation using magnetic beads. In contrast, in MLR with ART-18 added, Ts were primarily IL-2R- (ca. 10% of blasts). Thus, antirat p55 subunit IL-2R mAb do not inhibit MLR-generated Ts functionally operative in vitro and in vivo. IL-2R- Ts precursors requiring lymphokine(s) other than IL-2 may differentiate into IL-2-dependent Ts effectors. Such divergent IL-2 requirements for Ts growth in vitro may explain the Ts-sparing effects in allograft recipients treated with anti-IL-2R mAb.

Animals↗
PubMed1989

Mixed lymphocyte response-generated suppressor cell specificity in humans is major histocompatibility complex-restricted.

To formally test the hypothesis that allospecificity of the human mixed lymphocyte response-generated suppressor cells is restricted to the major histocompatibility complex, 18 primary mixed lymphocyte responses, using peripheral blood lymphocytes of 10 HLA-typed families, were used to generate suppressor effector cells. Responder lymphocytes shared one HLA haplotype with the stimulator cells. At day 10, the effector cells were tested for their ability to suppress proliferation of 55 test mixed lymphocyte responses consisting of naive autologous lymphocytes as responders and irradiated cells from individual family members as stimulators. Suppression was predicted when the test culture stimulators expressed the same HLA haplotype to which the suppressor cells were primed. There was statistically significant correlation between suppression and HLA haplotype sharing (p = 0.0143). In 6 out of 13 assays, however, we observed suppression that was not predicted on the basis of relevant HLA haplotype sharing. These stimulators shared only HLA-A2 with the priming haplotype. HLA antigen sharing was not seen in the 7 remaining, nonsuppressed cultures. We conclude that, within families, the effector function of in vitro generated suppressor cells is restricted by the major histocompatibility complex.

Haplotypes↗
PubMed1989

Prolongation of primate renal allograft survival by anti-Tac, an anti-human IL-2 receptor monoclonal antibody.

In an effort to produce specific immunosuppression through the targeting of those lymphocytes expressing cell surface interleukin 2 receptors in response to an allograft, the anti-human IL-2 receptor monoclonal antibody anti-Tac was administered to cynomolgus monkeys receiving renal transplants. The data demonstrate that anti-Tac produces a significant delay in renal allograft rejection and prolongs host survival in cynomolgus monkeys. Though higher doses of anti-Tac produce modest delays in rejection, there was a surprising finding of greatly prolonged survival in three of five monkeys treated with much lower doses of anti-Tac. Anti-Tac was not shown to be synergistic with cyclosporine in this model. Animals treated with anti-Tac developed high titers of antibodies against the murine monoclonal antibody after 6-8 days of treatment, associated with the disappearance of plasma anti-Tac staining of activated lymphocytes as measured by flow cytometry. The data confirm the utility of the IL-2 receptor as a target for immunosuppressive therapy, and suggest that investigations of dosage and of methods to reduce the immunogenicity of anti-IL-2 receptor agents may be beneficial.

Animals↗
PubMed1989

Selective sparing of suppressor cells generated in mixed lymphocyte response by an anti-interleukin-2 receptor antibody.

Recent investigations have shown that anti-IL-2 receptor antibodies can prolong cardiac allograft survival in animal models and can be used effectively as primary immunosuppressive therapy in human renal transplantation. While previous studies have established that helper and cytotoxic T cells require IL-2 for proliferation, the role of this lymphokine in suppressor cell development is uncertain. We therefore studied the effects of SA36.6G (a monoclonal antibody directed at the 55 kD chain of the high-affinity IL-2 receptor) on events occurring in the mixed lymphocyte reaction. As expected, when added at culture initiation, SA36.6G inhibited both the proliferative response to allogeneic stimulation, and the generation of cytotoxic T cells. These effects were not the result of altered growth kinetics. In contrast, the generation of suppressor cells with a polymorphic pattern of specificity was not blocked by SA36.6G. Cultures containing SA36.6G had decreased numbers of activated lymphoblasts, but among this activated cell population the proportion of 2H4+ cells was doubled (53 +/- 13% vs. 27 +/- 9%). SA36.6G also blocked the appearance of IL-2 receptors on activated cells as determined by flow cytometry. This relative sparing of suppressor cells by an anti-IL-2 receptor antibody suggests that these cells may either exhibit IL-2 independent proliferation, or utilize an IL-2 receptor not recognized by SA36.6G.

Antibodies, Monoclonal↗
PubMed1989

Decrease in phenotypically defined T helper inducer cells (T4+4B4+) and increase in T suppressor effector cells (T8+2H4+) in stable renal allograft recipients.

Two monoclonal antibodies, anti-2H4 and anti-4B4, reciprocally divide the T4+ (CD4+) and T8+ (CD8+) lymphocytes into T4+2H4+, T4+4B4+, T8+2H4+ and T8+4B4+ subsets. The T4+2H4+, T4+4B4+ and T8+2H4+ subsets possess suppressor-inducer, helper-inducer, and suppressor-effector function, respectively, as previously defined in a system of B cell immunoglobulin production. Using monoclonal antibodies, including anti-2H4 and anti-4B4, and flow cytometry, we monitored lymphocyte subpopulations in 66 renal allograft recipients. We found that patients with stable allograft function have a decrease in the percentage of total T4+ lymphocytes from 41.9 +/- 9.5% pretransplant (pre-Tx) to 36.3 +/- 13.9% posttransplant (post-Tx) (P less than 0.05). This decrease was seen mainly in the T4+4B4+ or helper-inducer subset from 20.8 +/- 4.7% (pre-Tx) to 16.0 +/- 6.3% (post-Tx) (P less than 0.005). Patients with stable function were also noted to have an increase in the percentage of total T8+ lymphocytes from 21.3 +/- 10.7% (pre-Tx) to 30.9 +/- 15.4% (post-Tx) (P less than 0.02). Examination of T8 subsets revealed that a statistically significant increase was seen in the T8+2H4+ or suppressor effector subset from 15.5 +/- 9.2% (pre-Tx) to 21.5 +/- 10.2% (post-Tx) (P less than 0.01). Additionally, serial studies on 14 patients revealed an increase in the %T4+2H4+ suppressor-inducer subset from 9.31 +/- 3.64% (pre-Tx) to 15.71 +/- 6.41% (post-Tx) (P less than 0.0025). Since the role of these subsets has not been established in alloimmunity, in vitro allogeneic studies of 2H4-enriched (2H4+) and 2H4-depleted (2H4-) lymphocytes from normal peripheral blood were performed. In the mixed lymphocyte reaction, 2H4+ cells proliferated less than 2H4- cells (cpm ratio 2H4+/2H4-: 0.63-0.84), but 2H4+ cells generated twice as much suppressor activity as 2H4- cells (ratio % suppression 2H4+/2H4-: 1.9-2.3). These results suggest that 2H4+ cells play a role in the suppressor limb of the alloimmune response and that the increase in cells of this phenotype in our transplant population may be responsible for the maintenance of stable allograft function.

Adult↗
PubMed1989

Interleukin 2 receptor expression on peripheral blood lymphocytes in association with renal allograft rejection.

Periodic assay of IL-2 receptor expression on the surfaces of peripheral blood lymphocytes might provide information predictive of in vivo immunologic events. This study compares two methods of determining IL-2 receptor expression after renal transplantation in cynomolgus monkeys. The first utilized single color staining of peripheral blood mononuclear cells with mouse anti-human IL-2 receptor monoclonal antibody followed by a fluorescein-labeled goat anti-mouse IgG antibody. Epics C cell sorter windows were set to count cells of the size and granularity of normal lymphocytes. The second utilized two-color staining with fluorescein-labeled anti-IL-2 receptor antibody, combined with phycoerythrin-labeled anti-CD4 antibody or with phycoerythrin-labeled anti-CD8 antibody. Two-color staining allowed the sorter windows to be enlarged to count all mononuclear cells, regardless of size or granularity, without introducing the contaminating effects of monocytes. Data obtained from single-color staining showed no consistent or significant expression of the IL-2 receptor on peripheral lymphocytes in association with the rejection process. Data obtained from two-color staining revealed an increase of IL-2 receptor expression on peripheral T cells of at least 10% from the postoperative baseline, which preceded the creatinine rise from allograft rejection in 13 of 13 animals. Increases in IL-2 receptor expression on T cells were not specific to rejection, however. Some animals in which treatment produced a delay of rejection showed a transient rise in IL-2 receptor expression around post-transplant day 5, which was not followed by a rise in creatinine. The two-color staining technique described provides a sensitive means of detecting IL-2 receptor expression in vivo and documents the association of increases in IL-2 receptor expression on T cells with rejection.

Animals↗
PubMed1989

Differential IL-2 receptor expression in renal allograft recipients treated with an anti-IL-2-receptor antibody.

Patients were entered into a randomized trial of prophylaxis for renal allograft rejection by the administration of an anti-human IL-2 receptor antibody, anti-Tac, during the first ten days posttransplant. Interleukin-2 receptor (IL-2 R) expression was measured using two anti-IL-2 R monoclonal antibodies (moAbs), anti-Tac and 1HT4-4H3. These two antibodies recognize closely spaced epitopes on the 55 kD chain of the IL-2 R. IL-2 R expression was examined on peripheral blood small lymphocytes in three groups of patients who received: (A) cyclosporine CsA and prednisone for baseline immunosuppression (n = 9); (B) anti-Tac with CsA and prednisone as baseline immunosuppression (n = 12); and (C) anti-Tac with azathioprine and prednisone as baseline immunosuppression (n = 5). We found that large numbers of T cells express IL-2 receptors despite the presence of anti-Tac (average of IL-2 R-positive cells at day of peak IL-2 R expression 56.0 +/- 20.8% in group A, 65.2 +/- 26.6% in group B, 21.0 +/- 7.4% in group C). IL-2 R expression did not correlate with clinical activity, and the presence or accessibility of epitopes on the same 55 kD chain varied dramatically from patient to patient.

Antibodies, Monoclonal↗