Role of the thymus in transplantation tolerance in miniature swine. I. Requirement of the thymus for rapid and stable induction of tolerance to class I-mismatched renal allografts

The almost uniform failure in transplant patients of tolerance-inducing regimens that have been found to be effective in rodents, has made it necessary to examine large animal models before testing of new approaches clinically. Miniature swine have been shown to share many relevant immunologic parameters with humans, and because of their reproducible genetics, have proved extremely useful in providing such a large animal model. We have previously shown that indefinite systemic tolerance to renal allografts in miniature swine is induced in 100% of cases across a two-haplotype class I plus minor histocompatibility antigen disparity by a 12-d course of Cyclosporine A (CyA), in contrast to irreversible rejection observed uniformly without CyA treatment. In the present study, we have examined the role of the thymus during the induction of tolerance by performing a complete thymectomy 21 d before renal transplantation. This analysis demonstrated a striking difference between thymectomized and nonthymectomized animals. Thymectomized swine developed acute cellular rejection characterized by a T cell (CD25(+)) infiltrate, tubulitis, endothelialitis and glomerulitis, and anti-donor CTL reactivity in vitro. Nonthymectomized and sham thymectomized animals had a mild T cell infiltrate with few CD25(+) cells and no anti-donor CTL response in vitro. These results indicate that the thymus is required for rapid and stable induction of tolerance.

Human cell-mediated rejection of porcine xenografts in an immunodeficient mouse model

BACKGROUND

In this study, we describe the development of a novel experimental system in which rejection of porcine skin grafts by human peripheral blood cells can be studied directly in vivo in immunodeficient mice.

METHODS

To construct a small animal model of discordant xenograft rejection, recombinase-activating gene-deficient mice (R-) lacking both mature B and T cells were grafted with porcine skin grafts and administered, by adoptive cell transfer, human cells stimulated in vitro with irradiated porcine peripheral blood cells to create Hu-R- mice.

RESULTS

R- mice accepted porcine skin grafts indefinitely without the need for immunosuppression. In contrast, Hu-R- mice were able to reject porcine skin grafts. Immunohistochemical analysis of rejecting skin grafts revealed the accumulation of human T cells around dermal porcine vessels and focally in the epidermis. Graft rejection was manifested by vascular endothelial cell proliferation, edema at the dermal-epidermal border, and perivascular hemorrhage. The tissue damage observed in the rejecting grafts was similar to that observed in delayed primate anti-porcine cell-mediated rejection of vascularized organ xenografts.

CONCLUSIONS

The development and characterization of a small animal model, to study cellular immune responses of human cells to discordant xenografts in vivo, should provide a convenient means for asking mechanistic questions related to discordant xenotransplantation, and may also provide a practical system for testing new approaches designed to prevent xenograft rejection.

Cytotoxicity and apoptosis in human renal allografts: identification, distribution, and quantitation of cells with a cytotoxic granule protein GMP-17 (TIA-1) and cells with fragmented nuclear DNA

In the present study, we analyzed human renal allografts using immunohistochemical techniques to determine the site, identity, and frequency of (a) cytotoxic and apoptotic cells, as identified by staining for GMP-17 (TIA-1), a component of cytotoxic granules; and (b) DNA fragmentation in situ, as detected by the TUNEL method. In acute cellular rejection (n = 15), GMP-17+ mononuclear cells accounted for 29% +/- 12% of the infiltrating cells in the interstitium (341 +/- 164/mm2) and were significantly more concentrated in tubulitis lesions, where they amounted to 65% +/- 14% of the mononuclear cells (96 +/- 61/mm2) (p < 0.01 versus interstitium). GMP-17+ mononuclear cells were also found in sites of endothelialitis. An estimated 80% of the GMP-17+ lymphocytes expressed CD8, and 10% to 20% expressed either CD4 or the macrophage marker CD14. The latter finding led us to analyze normal peripheral blood monocytes by flow cytometry, all of which were found to contain GMP-17. NK cells and neutrophils, which are known to express GMP-17, were detected only rarely in allografts. Specimens with cyclosporine A toxicity (n = 7) or acute tubular necrosis (n = 13) showed fewer GMP-17+ cells in the interstitium (22 +/- 46/mm2 and 62 +/- 50/mm2, respectively) and tubules (2 +/- 6/mm2 and 10 +/- 10/mm2, respectively) (all p < 0.01 versus rejection). These differences were due largely to less intense mononuclear cell infiltration. In cyclosporine A toxicity, however, the percentages of GMP-17+ mononuclear cells within tubules and the interstitium were significantly lower than in rejection (p = 0.02), whereas in acute tubular necrosis significantly lower percentages were found in the tubules (p = 0.04) but not in the interstitium. Native kidneys with end-stage diabetic nephropathy (n = 5) had very low proportions of GMP-17+ cells in interstitial infiltrates (7% +/- 6%) and in tubules (11% +/- 15%), although the infiltrates were focally intense (517 +/- 355/mm2). TUNEL+ cells were found in acute cellular rejection, predominantly in areas with intense mononuclear infiltrates and also within lesions of tubulitis and endothelialitis. Although some TUNEL+ cells were intrinsic renal cells, most appeared to be infiltrating mononuclear cells, and we were able to detect CD3 in some. In areas of intense cellular infiltration, the percentages of TUNEL+ cells (range, 0.5% to 4.2%) were comparable to those seen in the rat thymus, indicating a high level of apoptosis. Overall, in the allograft samples, the numbers of GMP-17+ cells and TUNEL+ cells were significantly correlated (r = 0.79; p < 0.01). These data provide new evidence that T cell (and possibly macrophage)-mediated cytotoxicity plays an important role in acute renal allograft rejection, particularly in the case of tubular injury, and furthermore suggest that apoptosis may be a mechanism not only for graft cell destruction, but also for elimination of activated T cells in the infiltrate.

Pig to monkey bone marrow and kidney xenotransplantation

BACKGROUND

The intensity of discordant xenograft cellular rejection makes it unlikely that safe doses of immunosuppressive drugs will alone be sufficient to permit long-term survival. We have therefore concentrated our efforts on establishing tolerance to xenogeneic organs through lymphohematopoietic chimerism and the elimination of preformed natural antibodies (nAbs).

METHODS

Here we report the most recent series of 11 technically successful porcine to nonhuman primate transplantation procedures. In eight experimental animals induction therapy consisted of (1) 3 x 100 cGy nonlethal whole body irradiation (day -6 and day -5) to all animals, (2) horse anti-human thymocyte globulin (day -2, day -1, and day 0) to seven of the animals, (3) 700 cGy thymic irradiation (day -1) to five of the animals, and (4) pig bone marrow infused on day 0 (2-9 x 10(8)/cells/kg). On day 0, just before the renal xenograft, the recipient was splenectomized, and antipig nAbs were removed by means of perfusion of the monkey's blood through either a pig liver (n = 6) or a Gal-alpha (1,3)-Gal adsorption column (n = 5). There control animals did not receive this pretransplantation induction therapy but did undergo hemoperfusion and posttransplantation immunosuppression identical to the experimental animals. All 11 recipients were treated after transplantation with cyclosporin A and 15-deoxyspergualin. Recombinant pig-specific growth factors (interleukin-3 and stem cell factor) were given to six experimental animals from day 0 until the termination of the experiment.

RESULTS

Analysis of recipients' sera by means of flow cytometry indicated the effective removal of immunoglobulin M and immunoglobulin G nAbs by either liver perfusion or column adsorption. In the eight experimental animals, nAb titers remained low until death (up to 15 days), but in the three control animals nAb titers increased substantially with time. The longest surviving recipient maintained excellent kidney function with creatinine levels at 0.8 to 1.3 mg/dl throughout its course. Death occurred at day 15 from complications caused by a urinary leak and pancytopenia. Histologic examination of the xenograft revealed only focal tubular necrosis and cytoplasmic vacuolization, with trace amounts of fibrin and C3 in peritubular capillaries. In this animal a fraction of the peripheral blood cells (3%) at day 7 were of pig origin as detected by pig-specific monoclonal antibodies. In addition, colony-forming assays performed on a bone marrow biopsy specimen taken at day 14 indicated that approximately 30% of the relatively few myeloid progenitors detected were of swine origin.

CONCLUSIONS

We have demonstrated that our protocol is effective in the prevention of hyperacute rejection and in the maintenance of excellent function of the renal xenograft for up to 15 days. These results also indicate that at least short-term engraftment of the xenogeneic donor bone marrow cells is possible to achieve in this discordant large animal combination. Longer survivals will be required to assess the possible effect of this engraftment on induction of tolerance.

Molecular and cellular events implicated in local tolerance to kidney allografts in miniature swine

Long-term tolerance to class I-mismatched renal allografts can be induced in miniature swine by treatment with a short course of cyclosporine (CsA). Kidney recipients treated with CsA and untreated control kidney recipients both demonstrated infiltration of the transplanted kidney by mononuclear cells, which reached a maximum between postoperative days 8 and 11. Recipients that did not receive the tolerizing regimen rejected their grafts between postoperative days 8 and 12 in this model. The kinetics of cytokine gene expression, including interleukin (IL)-1alpha, IL-1beta, IL-2, IL-6, IL-10, tumor necrosis factor, and interferon-gamma (IFN-gamma), within the grafted kidney of rejector and acceptor animals, were determined using Northern blot hybridization. A strong correlation between rejection and up-regulation of the IFN-gamma gene was observed, whereas animals with long-term tolerance showed low levels of IFN-gamma, but high levels of IL-10 gene transcription. None of the other cytokine genes demonstrated a reproducible pattern of expression that correlated with acceptance/rejection of allografts. Analysis of transcription patterns of cytokine genes in mononuclear cells purified from renal grafts confirmed the initial observations made on biopsies. The phenotype of graft-infiltrating cells (GIC) showed a dominance of CD8+ cells, with an average of 66% single-positive cells and 19% CD4/CD8 double-positive cells, compared with 30% and 14%, respectively, for peripheral cells. Predominance of CD8+ GIC was dictated neither by the MHC antigen disparity nor the rejector/acceptor status. These results, therefore, suggest that GIC represent a regulated combination of mononuclear cells producing local immune mediators that, in part, control the fate of allografts in this large animal model.

Healing corneas express embryonic fibronectin isoforms in the epithelium, subepithelial stroma, and endothelium

The cornea is a simple, nonvascularized structure, advantageous for studying the molecular components of epithelial and stromal wound repair. Fibronectin (Fn), of uncertain source and composition, accumulates in healing corneas. We postulated that local synthesis of Fn occurs, as exogenous plasma/tear-derived Fn, which lack the embryonic EIIIA and EIIIB segments, have no consistent beneficial effect on healing. Two contrasting corneal wounds were examined by in situ hybridization: a wound of the anterior stroma, basement membrane, and epithelium (anterior excimer laser keratectomy) and a superficial wound restricted to the epithelium that preserved the basement membrane (mechanical scrape). Both wounds heal without scarring. In normal corneas, only the endothelium had detectable Fn mRNA, containing the V and EIIIB domains, sporadically and at low levels. After anterior keratectomies, extensive expression of Fn mRNA occurred in a specific distribution that changed during the phases of healing. Before re-epithelialization (days 1 and 2) V+, EIIIA+, and EIIIB+ isoforms were diffusely found in stromal cells under and adjacent to the wound. After re-epithelialization (days 3 to 42) and reconstitution of laminin in the regenerating basement membrane zone, V+, EIIIA+, and EIIIB+ isoform synthesis was largely restricted to subepithelial stromal cells at the epithelial/stromal interface. In addition, the corneal epithelial cells focally expressed Fn mRNA. The endothelium showed increased levels of V+, EIIIA+, and EIIIB+ Fn mRNA in open and recently re-epithelialized wounds. At 12 weeks after keratectomy, Fn mRNA expression returned to control levels. In contrast, scrape wounds had only a modest increase of stromal and endothelial Fn mRNA (EIIIA+, EIIIB+, and V+) during the first 7 days and no evidence of epithelial Fn synthesis. Embryonic Fn isoforms are synthesized transiently by the cornea in response to even the most superficial wounds and are likely to be relevant to corneal healing and restoration of structure without scar formation.

Accelerated atheromatous lesions in mouse hearts transplanted to apolipoprotein-E-deficient recipients

Arteriopathy, sometimes termed accelerated atherosclerosis, often impairs transplants. We employed apolipoprotein-E-deficient, hypercholesterolemic mice to determine how the hyperlipidemic environment affected transplanted hearts. Strain 129 hearts transplanted to C57BL/6 normal or C57BL/6 apolipoprotein-E-deficient recipients were evaluated by immunochemical and histological techniques. Analyses were possible both of differences in the coronary lesions that developed in a normolipidemic as compared with a hyperlipidemic environment and of the coronary atherosclerotic process in transplanted hearts compared with native hearts in the same hyperlipidemic environment. Aortas and coronary arteries of transplanted aortas in both recipient groups developed florid intimal thickening by 4 to 10 weeks, with marked lipid deposition, foamy macrophages, and infiltration of smooth muscle alpha-actin-positive cells in apolipoprotein-E-deficient mice. Lipid was layered against the internal elastic lamina as in human transplants. VCAM-1 was increased in various sites in both groups. Allotransplants to apolipoprotein-E-deficient recipients had more severe aortic and coronary lesions with characteristic T cell infiltration than native hearts. In this sense, transplants suffered from accelerated atherosclerosis. The character of coronary vascular changes in transplanted hearts was distinctly affected by their lipid environment, but their severity, in terms of luminal encroachment, was not markedly different.

Adhesion molecules in renal disease

This review updates the advances in basic and clinical studies of adhesion molecules in renal disease that have appeared in 1995. The primary focus is on ischemia and transplantation.

Intercellular adhesion molecule-1-deficient mice are protected against ischemic renal injury

Studies in the rat have pointed to a role for intercellular adhesion molecule-1 (ICAM-1) in the pathogenesis of acute tubular necrosis. These studies used antibodies, which may have nonspecific effects. We report that renal ICAM-1 mRNA levels and systemic levels of the cytokines IL-1 and TNF-alpha increase 1 h after ischemia/ reperfusion in the mouse. We sought direct proof for a critical role for ICAM-1 in the pathophysiology of ischemic renal failure using mutant mice genetically deficient in ICAM-1. ICAM-1 is undetectable in mutant mice in contrast with normal mice, in which ICAM-1 is prominent in the endothelium of the vasa recta. Mutant mice are protected from acute renal ischemic injury as judged by serum creatinine, renal histology, and animal survival . Renal leukocyte infiltration, quantitated morphologically and by measuring tissue myeloperoxidase, was markedly less in ICAM-1-deficient than control mice. To evaluate whether prevention of neutrophil infiltration could be responsible for the protection observed in the mutant mice, we treated normal mice with antineutrophil serum to reduce absolute neutrophil counts to < 100 cells/mm3. These neutrophil-depleted animals were protected against ischemic renal failure. Anti-1CAm-1 antibody protected normal mice against renal ischemic injury but did not provide additional protection to neutrophil-depleted animals. Thus, ICAM-1 is a key mediator of ischemic acute renal failure likely acting via potentiation of neutrophilendothelial interactions.

Long-term acceptance of primarily vascularized renal allografts in miniature swine. Systemic tolerance versus graft adaptation

We have previously demonstrated that tolerance to two-haplotype class I-mismatched renal allografts can be induced uniformly by a short course of cyclosporine. We report here that following transplant nephrectomy, 8 such long-term acceptor animals all accepted a second renal transplant MHC matched to the original donor without additional immunosuppression. These results indicate that the mechanism of tolerance to primarily vascularized renal allografts involves modification of the host's immune system by the first transplant. To assess the possibility that "graft adaptation" is also involved in the maintenance of tolerance, we retransplanted class I-disparate kidneys from tolerant animals into naive recipients MHC matched to the original recipient. Three of 4 such transplants were rejected acutely, while one animal demonstrated a markedly prolonged survival, but also eventually rejected. These results, therefore, demonstrate that: (1) graft adaptation is not required in order to maintain tolerance; (2) graft acceptance involves induction of systemic tolerance; and (3) graft adaptation may participate in kidney graft prolongation but is not sufficient to transfer tolerance to a secondary host.

Coronary atherosclerosis in transplanted mouse hearts. IV Effects of treatment with monoclonal antibodies to intercellular adhesion molecule-1 and leukocyte function-associated antigen-1

Atherosclerotic lesions in the coronary arteries of transplanted mouse hearts manifest high expression of ICAM-1 (CD54), especially on endothelial surfaces, and of LFA-1 (CD11a) on migratory mononuclear cells. The possible participation of cellular adhesion systems in the evolution of these complex lesions was suggested by the increased expression of intercellular adhesion molecule-1 (ICAM-1) and leukocyte function-associated antigen-1 (LFA-1) and also by our previous studies with this experimental system. In our studies, we have found that administration of a monoclonal antibody (mAb) to gamma-interferon will greatly suppress coronary changes, and gamma-interferon is known to stimulate the formation of these adhesion molecules. The present experiments were to evaluate how administration to murine heart transplant recipients of mAbs against ICAM-1, LFA-1, or both affected the development of coronary atherosclerosis. It was found that treatment with either mAb alone did not alter the severity of coronary atherosclerosis, but that both mAbs given together can significantly suppress lesion formation at 30 days compared with controls (P < 0.044). Continuing treatment was even more effective when extended to 60 days (P < 0.003). The mAbs to ICAM-1 and LFA-1 bound their targets in vivo (primarily endothelium and mononuclear cells, respectively), but complete, long-term saturation of combining sites was not attained, even with very high doses. No appreciable reduction in arterial endothelial ICAM-1 expression was evident. It is concluded that the ICAM-1/LFA-1 system is of central importance in the evolution of accelerated coronary atherosclerosis.

Embryonic fibronectin isoforms are synthesized in crescents in experimental autoimmune glomerulonephritis

Crescents are a severe and stereotyped glomerular response to injury that occur in several forms of glomerulonephritis that progress to renal failure. The key pathogenetic step that leads to glomerular scarring in unknown, but fibronectin (FN), the clotting system, macrophages, and proliferating parietal epithelial cells are known to participate. This study was designed to determine whether FN is synthesized locally, and in what molecular isoform, and whether cytokines known to promote FN synthesis are present in the crescent. Rats immunized with bovine glomerular basement membrane develop cellular crescents by 14 days and fibrous crescents and glomerulosclerosis by 35 days. In situ hybridization was performed with oligonucleotides specific for sequences common to all FN isoforms (total FN) or sequences specific for the alternatively spliced segments (EIIIA, EIIIB, and V). Throughout the time period (14, 21, and 35 days) all crescents and glomerular tufts contained cells with strong ISH signals for total and V+ mRNA, with the strongest signals present in large cellular crescents at day 21. In contrast, EIIIA+ and EIIIB+ mRNAs showed maximal abundance within sclerosing crescents at 35 days. Protein deposition of EIIIA+, EIIIB+, and V+ FN isoforms was confirmed by immunofluorescence with segment-specific FN antibodies. Transforming growth factor-beta and interleukin-1 beta, both known to promote FN synthesis, were found in cellular crescents (days 14 and 21) and were still present, but greatly diminished, in the sclerotic phase (day 35). In summary, EIIIA-, EIIIB-, and V+ FN mRNA plasma isoforms predominate in cellular crescents, whereas in the fibrosing stage, mainly the oncofetal EIIIA+, EIIIB+, and V+ isoforms are synthesized and accumulate.

Anti-CD3:anti-IL-2 receptor-bispecific mAb-mediated immunomodulation. Low systemic toxicity, differential effect on lymphoid tissue, and inhibition of cell-mediated hypersensitivity

An anti-CD3:anti-CD25 (CD3,25) bispecific mAb was developed with the objective of combining the advantages of the parent anti-CD3 and anti-CD25 mAbs. The in vivo effects of the CD3,25 were examined in comparison to the parent Abs. The CD3,25 was well tolerated in vivo, in contrast to the parent anti-CD3 mAb, which induced systemic toxicity in recipient animals. Anti-CD3 mAb induced cell death, lymphoblast formation, and T cell activation in peripheral lymphoid organs; these were observed to a lesser extent in CD3,25-treated animals. In the thymus, anti-CD3 caused a progressive depletion of the CD4+ CD8+ "double positive" thymocytes, which was not seen in CD3,25-treated animals. This finding suggests that monovalent CD3 binding is insufficient to induce thymocyte apoptosis. Animals treated with a combination of anti-CD3 and anti-CD25 mAbs demonstrated changes in the lymphoid organs that were similar to anti-CD3-treated mice. This finding demonstrates that the effect of the CD3,25 is different than the sum of the parent Abs and suggests that the bispecific nature of the CD3,25 results in a reagent with unique immunomodulatory properties. The functional efficacy of the CD3,25 was assessed in a murine model of delayed-type hypersensitivity. The CD3,25 was as effective as the anti-CD3 mAb in inhibiting the delayed-type hypersensitivity reaction and was more effective than the parent anti-CD25 mAb. These data demonstrate that appropriately designed bispecific mAbs can be used as effective immunosuppressive agents with low systemic toxicity.

Anti-CD3:anti-IL-2 receptor-bispecific mAb-mediated immunomodulation. Low systemic toxicity, differential effect on lymphoid tissue, and inhibition of cell-mediated hypersensitivity

An anti-CD3:anti-CD25 (CD3,25) bispecific mAb was developed with the objective of combining the advantages of the parent anti-CD3 and anti-CD25 mAbs. The in vivo effects of the CD3,25 were examined in comparison to the parent Abs. The CD3,25 was well tolerated in vivo, in contrast to the parent anti-CD3 mAb, which induced systemic toxicity in recipient animals. Anti-CD3 mAb induced cell death, lymphoblast formation, and T cell activation in peripheral lymphoid organs; these were observed to a lesser extent in CD3,25-treated animals. In the thymus, anti-CD3 caused a progressive depletion of the CD4+ CD8+ "double positive" thymocytes, which was not seen in CD3,25-treated animals. This finding suggests that monovalent CD3 binding is insufficient to induce thymocyte apoptosis. Animals treated with a combination of anti-CD3 and anti-CD25 mAbs demonstrated changes in the lymphoid organs that were similar to anti-CD3-treated mice. This finding demonstrates that the effect of the CD3,25 is different than the sum of the parent Abs and suggests that the bispecific nature of the CD3,25 results in a reagent with unique immunomodulatory properties. The functional efficacy of the CD3,25 was assessed in a murine model of delayed-type hypersensitivity. The CD3,25 was as effective as the anti-CD3 mAb in inhibiting the delayed-type hypersensitivity reaction and was more effective than the parent anti-CD25 mAb. These data demonstrate that appropriately designed bispecific mAbs can be used as effective immunosuppressive agents with low systemic toxicity.

Real-time monitoring of renal function during ischemic injury in the rhesus monkey

The presence of delayed graft function (DGF) following cadaver donor renal transplantation is associated with inferior graft survival as well as decreased patient survival. Delay in onset of function eliminates a valuable indicator of allograft viability, which is not easily replaced by standard diagnostic procedures. The purpose of this study was to demonstrate that a new clearance technique could be used to measure renal function minute to minute and under conditions similar to those observed in humans in the immediate posttransplantation period. A monkey model was used to provide controlled conditions. Increasing levels of ischemic injury were produced in 12 Rhesus monkeys by renal hilum cross-clamping. Real-time measurements of glomerular filtration rate (GFR) were obtained from the rate of clearance of the extracellular fluid of the GFR agent 99mTc-DTPA, as measured with a specially designed external radioactivity counting device called the ambulatory renal monitor, or ARM. GRF was measured every 2-5 min as the slope (k) of the log of activity measured minute to minute versus time. GFR measurements were correlated with blood urea nitrogen (BUN), plasma creatinine (Cr), routine light microscopy, and measurement of proliferating cell nuclear antigen (PCNA), a marker of cell proliferation. Large changes in renal function due to ischemia or ureteral obstruction were observed within minutes. In addition, the rate constant on Day 1 was predictive of peak serum Cr(R =--0.86, R2=.74, p = .0001). Acute tubular necrosis (ATN) resolution was reflected more quickly when using the rate constant (Day 1) than when using either BUN or plasma Cr (Day 3-4). Because of renal functional reserve, BUN and plasma Cr were relatively insensitive indicators of mild to moderate reductions in GFR as compared with the rate constant. We conclude that ARM is a simple method which provide an accurate, near real-time GFR readout with potential applications not only for the clinical management of patients with DGF, but also as a research tool in acute renal failure (ARF).

Mixed allogeneic chimerism and renal allograft tolerance in cynomolgus monkeys

We have developed a nonmyeloablative preparative regimen that can produce mixed chimerism and renal allograft tolerance between MHC-disparate nonhuman primates. The basic regimen includes ATG, nonmyeloablative total-body irradiation (TBI, 300 rads), thymic irradiation (TI, 700 rads), and donor bone marrow infusion. Kidney allografts from MHC-mismatched donors were transplanted with various manipulations of the preparative regimen. Monkeys treated with the basic regimen alone (n = 2) rejected allografts by day 15. With the addition of cyclosporine (CsA) for one month (n = 3), one monkey developed multilineage mixed chimerism and renal allograft tolerance thereafter (> 430 days). To reduce the toxicity of the preparative regimen, TBI was fractionated to 150 rads on two successive days in subsequent studies. All monkeys receiving this modified regimen (n = 4) developed multilineage chimerism with fewer side effects and accepted renal allografts long-term with no further immunosuppression (196 days, 198 days, > 150 days, and > 40 days). In long-term survivors, donor-specific nonreactivity was confirmed by MLR and skin transplantation. Three monkeys treated with the basic regimen plus CsA but with only 150 rads of TBI (n = 1) or no TBI (n = 2) did not develop multilineage chimerism and grafts were rejected (day 40-50) soon after the CsA discontinuation. Monkeys treated with the same regimen, but without DBM (n = 2), rejected kidney allografts by day 52. Therefore, at least transient engraftment of DBM appears to be essential for induction of donor specific tolerance in this monkey model.

Making global telemedicine practical and affordable: demonstrations from the Middle East

OBJECTIVE

The purpose of this study was to demonstrate the first use of voice-grade telephone lines for the international transmission of both high-resolution digital images (radiology and pathology) and video in near real-time.

MATERIALS AND METHODS

Eight live demonstrations were performed from the United Arab Emirates and the Kingdom of Saudi Arabia at the invitation of the respective ministries of health. Thirty radiologic studies (CT, MR, and radiographs) were digitized, compressed, and transmitted to Cambridge, MA, where they were interpreted on diagnostic workstations (1792 x 2252 display matrix) by a team of subspecialist radiologists. Near real-time image transmission was achieved by combining wavelet-based image compression (average compression ratio of 23:1) and multiplexing technology that used four phone lines simultaneously. During each demonstration, one pathology image was transmitted from Cambridge to the demonstration site, where it was interpreted by a visiting pathologist. Video-conferencing was implemented with a 64-kilobits-per-sec leased line from the United Arab Emirates and with four multiplexed telephone lines from Saudi Arabia.

RESULTS

For teleradiology and telepathology, transmission times ranged from 2-5 min per image. Image fidelity was judged to be of diagnostic quality in all transmitted cases. The video link to the United Arab Emirates was highly reliable. Bandwidth for videoconferencing from Saudi Arabia was marginal on four voice-grade telephone lines, resulting in some downtime (10-20%). Live consultations provided by subspecialists in Cambridge assisted in the management of patients at both venues. The system was well received by both the referring physicians in the Middle East and the participants in the United States.

CONCLUSION

Image compression and multiplexing technologies enabled high-resolution teleradiology and telepathology as well as real-time video consultations over international telephone lines. While telecommunications systems are advancing rapidly in many parts of the world, those areas most in need of telemedicine services are likely to be the last to upgrade their telecommunications infrastructures. This "proof of concept" article outlines a practical and affordable approach that makes telemedicine more accessible to underserved areas worldwide.

Flow cytometric analysis of DNA ploidy, percent S-phase fraction, and total proliferative fraction as prognostic indicators of local control and survival following radiation therapy for prostate carcinoma

PURPOSE

Treatment recommendations for localized prostate cancer may be improved by the identification of tumor factors prognostic for local control and survival. In this retrospective study, flow cytometric deoxyribonucleic acid (DNA) ploidy analysis and cell cycle analysis were performed on paraffin-embedded biopsy material to determine if additional prognostic factors could be identified in patients treated with radiation therapy.

METHODS AND MATERIALS

Seventy patients with T1-4NxM0 tumors were identified in whom the primary treatment had been radical radiation therapy with no prior or concurrent endocrine therapy and in whom sufficient prostatic tissue was available for flow cytometric analysis. There were 40 diploid, 26 aneuploid, and 4 multiploid cases. Aneuploid and multiploid cases were combined for analysis. Cell cycle data were obtained on all diploid and 10 aneuploid cases.

RESULTS

The histologic differentiation of the tumor (well or moderate vs. poor) was an independent predictor of overall survival and disease-free survival (p = 0.05 and 0.01, respectively). Local control was worse in the poorly differentiated patients, although this was not statistically significant in a multivariate analysis (p = 0.08). Neither T-stage, deoxyribonucleic acid ploidy (diploid vs. nondiploid), percent S-phase fraction, nor total proliferative fraction (S-phase fraction + G2M) significantly predicted for any of these endpoints. Within the diploid and well or moderately differentiated subgroup (n = 25), S-phase (< 4.2 vs. > or = 4.2) was a significant predictor of local control (100% vs. 51%, p = 0.03). A comparable distinction could be made using total proliferative fraction (< 10% vs. > or = 10%) with local control rates of 100% vs. 56% (p = 0.05). Among the poorly differentiated tumors, no similarly favorable subgroup was identified.

CONCLUSIONS

This retrospective and multivariate analysis identifies both histology and percent S-phase or total proliferative fraction as predictors of local control following irradiation, and confirms that histology, but not DNA ploidy, is significant for overall survival. If these previously unreported findings are confirmed by prospective studies, S-phase should be added to histology as a parameter in the evaluation of clinical trials.

Differential expression of alternatively spliced fibronectin in normal and wounded rat corneal stroma versus epithelium

PURPOSE

The polymerase chain reaction was used to examine fibronectin (FN) expression during corneal scrape wounding with specific attention to the presence, absence, or gross changes of alternatively spliced FN as differentially expressed in the corneal stroma versus the epithelium in normal and wounded tissue.

METHODS

Specific FN cDNA sequences were synthesized from rat cornea with total RNA and were amplified using various sets of synthetic oligonucleotide primers.

RESULTS

The authors observed the presence and sustained the expression of total FN, EIIIA, EIIIB, and V-region FN mRNA in normal and injured corneal stroma for up to 3 weeks after scrape wounding. In contrast, complementary overlying epithelial samples were virtually devoid of FN message.

CONCLUSIONS

These data suggest that functionally different, alternatively spliced FN isoforms may be involved both in the maintenance of the normal cornea and in wound healing, and that their synthesis occurs in situ principally by the stroma rather than by the epithelium.

Coronary atherosclerosis in transplanted mouse hearts. III. Effects of recipient treatment with a monoclonal antibody to interferon-gamma

Obstructive coronary arterial lesions in the vessels of transplanted hearts result from a complex process in which the immune response of the recipient plays a pivotal role. We have devised an experimental system in which mouse hearts, transplanted after brief treatment with mAbs to CD4 and CD8, survive and contract for many weeks. A high percentage of such hearts develop advanced, obstructive coronary lesions by 4 weeks. Migratory cells of recipient origin localize in the linings of affected vessels, and mediators of inflammation, including adhesion molecules, are present in increased amounts in characteristic locations. Histocompatibility antigen expression is also increased, and these substances may promote the formation of vascular lesions by acting as targets for immune responses. IFN-gamma synthesis has been demonstrated in grafts where it is postulated to be important in the expression of MHC molecules and macrophage activation. Here we report that continuing treatment with R4-6A2, an mAb to IFN-gamma, strikingly inhibits the formation of obstructive vascular lesions in mouse hearts transplanted to recipients incompatible for either class I or class II antigens (P < 0.0001 for the former and P < 0.03 for the latter). Immunohistologic studies showed reduction of the class II-positive mononuclear infiltrate, but focally enhanced endothelial class I expression remained. The mechanism for this effect of anti-IFN-gamma probably extends beyond the influence of anti-IFN-gamma on increased expression of histocompatibility antigens.