Stimulation of in vivo angiogenesis by cytokine-loaded hyaluronic acid hydrogel implants

Crosslinked hyaluronic acid (HA) hydrogels were evaluated for their ability to elicit new microvessel growth in vivo when preloaded with one of two cytokines, vascular endothelial growth factor (VEGF) or basic fibroblast growth factor (bFGF). HA film samples were surgically implanted in the ear pinnas of mice, and the ears retrieved 7 or 14 days post implantation. Histologic analysis showed that all groups receiving an implant demonstrated significantly more microvessel density than control ears undergoing surgery but receiving no implant (p < 0.01). Moreover, aqueous administration of either growth factor produced substantially more vessel growth than an HA implant with no cytokine. However, the most striking result obtained was a dramatic synergistic interaction between HA and VEGF. Presentation of VEGF in crosslinked HA generated vessel density of NI = 6.7 at day 14, where NI is a neovascularization index defined below, more than twice the effect of the sum of HA alone (NI = 1.8) plus VEGF alone (NI=1.3). This was twice the vessel density generated by co-addition of HA and bFGF (NI=3.4, p<0.001). New therapeutic approaches for numerous pathologies could be notably enhanced by the localized, synergistic angiogenic response produced by release of VEGF from crosslinked HA films.

Glycosaminoglycan Hydrogels as Supplemental Wound Dressings for Donor Sites

Chemically crosslinked glycosaminoglycan (GAG) hydrogel films were evaluated as biointeractive dressings in a porcine model for donor-site autograft wounds. Multiple 5 x 5 x 0.03 cm wounds were created on the dorsum of pigs. Half of the wounds were treated with a GAG film plus an occlusive dressing (Tegaderm), whereas the other half were treated with Tegaderm alone. At 3, 5, or 7 days after surgery, the partially healed wounds were excised and evaluated histologically for three animals at each time point. By day 3, epithelial cells had proliferated and migrated from wound edges and from epithelial islands associated with residual hair follicles to begin to cover the wound bed. A statistically significant increase in coverage was observed for GAG + Tegaderm-dressed wounds than for those with Tegaderm alone at day 3 and day 5 post-surgery. By day 7, all treatment groups were completely healed. Thus, GAG hydrogels accelerated wound healing by enhancing re-epithelialization.

Effects of thermal injury on skeletal metabolism in two strains of mice

Long-term growth retardation occurs in children and osteopenias occur among children and adults who have been burned or suffer other injuries that result in a systemic inflammatory response. The purpose of this study was to define some of the growth, and to determine cancellous and cortical bone changes that occur following thermal injury in several contrasting strains of mice. Male C3H/HeN and Balb/c mice were given about a 20% total body thermal injury and 10 days later skeletal tissues were collected. The bone ash weights of the burned animals from both strains were less than their sham controls. In both strains, cancellous bone volumes were less in the burned animals than in their respective sham or baseline control groups. The loss of bone was particularly evident in the secondary spongiosa regions and also included a decrease in trabecular thickness and connectivity and an increase in trabecular separation. Longitudinal (endochondral) growth was suppressed in the burn animals. In the burned animals, indices of cancellous bone formation were substantially reduced whereas those in cortical bone were essentially nonexistent. The numbers of osteoclasts were increased in cancellous bone, and endocortical eroded surface was increased in the burn animals. These data show that there are rapid and profound changes in skeletal growth and metabolism in an experimental model of thermal injury. In general, a greater relative response was observed in the Balb/c vs. the C3H/HeN strain. Thermal injury resulted in a rapid and dramatic suppression of bone formation and endochondral growth with increased bone resorption in both cancellous and cortical bone.

Myocyte function and [Ca 2+ ]i homeostasis during early allogenic heart transplant rejection

BACKGROUND

Recent studies from our laboratory have demonstrated that in vivo contractile function of rejecting mouse heterotopic abdominal heart allografts 5 days after transplantation is depressed to 40% of that of syngenic controls, and that this depression of function is prevented by the nitric oxide synthase (NOS) inhibitor NG-monomethyl-l-arginine. However, the mechanisms of altered myocyte function caused by nitric oxide production in this setting are not established.

METHODS

We measured intracellular calcium concentration ([Ca2+]i) transients (fluo-3, confocal microscopy), fractional shortening (video motion), and L-type Ca2+ currents (whole-cell patch clamp) 5 days after transplantation in ventricular myocytes freshly isolated from syngenic (Balb/C into Balb/C) and allogenic (Balb/C into C3H) transplants.

RESULTS

L-type Ca2+ currents, [Ca2+]i transient amplitudes, and fractional shortening did not differ between nonrejecting, syngenic and rejecting, allogenic transplants. Catecholamine responsiveness as analyzed by the change in the peak [Ca2+]i transient induced by 100 nM isoproterenol was also similar. Superfusion with l-arginine, an NOS substrate, caused decreased shortening with no change in [Ca2+]i transients in allogenic myocytes, but had no effect in syngenic myocytes.

CONCLUSIONS

Depressed contractile function of rejecting allogenic heart transplants in vivo appears to be caused in part by an NOS-dependent decrease in myofilament Ca2+ sensitivity.

Functional importance and caffeine sensitivity of ryanodine receptors in primary lymphocytes

Calcium signaling patterns are important for the specific regulation of activation and effector function in lymphocytes. Studies of [Ca2+]i regulation in lymphocytes, including the involvement of ryanodine receptors (RyR) and the importance of caffeine-sensitive pools, have been carried out mainly in lymphocyte cell lines and the presence and functional importance of these pools in primary lymphocytes has not been addressed. Here we show by confocal microscopy that caffeine caused a prompt but transitory increase of [Ca2+]i in primary lymphocytes, an effect that was inhibited by pre-treatment with ryanodine. Furthermore, the increase of [Ca2+]i in CD4+ and CD8+ MLR T lymphocytes stimulated by 5 microg/ml concanavalin A was significantly inhibited by pretreatment with caffeine. In functional studies, caffeine decreased cytotoxicity against myocyte target cells which is probably related to an altered calcium signaling in CD8+ MLR lymphocytes. Caffeine also terminated spontaneous Ca2+ oscillations and induced a rise in [Ca2+]i in CD4- and CD8- MLR lymphocytes probably of B cell origin. These results demonstrate that caffeine alters Ca2+ signaling in primary lymphocytes, and suggest that RyR, probably the skeletal muscle receptor (RyR-1) and brain receptor (RyR-3), are involved in mediating this effect. It is also possible that blocking of inositol-1,4,5-triphosphate (IP3) receptors is involved in the effects of caffeine on lymphocyte activation.

Interleukin-18 production following murine cardiac transplantation: correlation with histologic rejection and the induction of INF-gamma

Interleukin-18 (IL-18) and IL-12 have been shown to play an important role in the induction of interferon-gamma (IFN-gamma). IFN-gamma induces the proliferation of T cells and natural killer (NK) cells and augments the Th1 immune cascade. The role of IL-18 and IL-12 in the induction of IFN-gamma following allogeneic heart transplantation has not been described. We sought to characterize the IL-12 and IL-18 response to murine allogeneic heart transplantation, particularly with respect to IFN-gamma production and histologic transplant rejection. Forty-eight heterotopic heart transplants were performed in two groups of mice: syngeneic C3H/HeN to C3H/HeN mice and allogeneic BALB/C to C3H/HeN mice. Transplants were followed out to 2, 6, 10, and 14 days. Six transplants were performed in each group. Serum and splenic samples were used to evaluate the cytokine response by ELISA. Explanted heart tissue was processed for evidence of histologic rejection, and RT-PCR was performed to evaluate the IL-12, IL-18, and IFN-gamma signal qualitatively. Analysis of variance (ANOVA), Fisher's projected least significant difference (PLSD) was used for statistical analysis. Transplant rejection occurred in the allogeneic group histologically by day 6 and clinically by day 10. Serum IFN-gamma levels rose significantly by day 6 in the allogeneic group and then continued to rise in the splenocyte cultures. Serum IL-18 also rose significantly in the allogeneic group at day 6 compared with syngeneic group. RT-PCR revealed that the allogeneic tissue contained an increased signal for IL-12, IL-18, and IFN-gamma beginning at day 6 and peaking at day 10 after transplant. Beginning 6 days after transplantation, IL-12 and IL-18 appear to play a significant role in the induction of IFN-gamma in allogeneic heart transplants.

Cardiac unloading alters contractility and calcium homeostasis in ventricular myocytes

Altered cardiac workload has an important effect on myocyte structure and function. Cardiac hypertrophy resulting from an increase in load has been studied extensively in the past. However, the effects of unloading and atrophy have recently become of more interest since devices for mechanical left ventricular unloading have been introduced into clinical practice for the treatment of patients with terminal heart failure, and a resulting improved cardiac and myocyte contractility have been reported. We used the heterotopic abdominal mouse heart transplant model in order to study the effects of 5 days of unloading on cell size (confocal microscopy), contractility (fractional shortening: video motion), calcium homeostasis ([Ca(2+)](i)transients, SR Ca(2+)content); and L-type Ca(2+)and sodium/calcium exchanger currents (whole cell patch clamp technique). We found unloading caused decreased cell volume consistent with atrophy. An increased fractional shortening and [Ca(2+)](i)transient were observed in myocytes from unloaded hearts as compared with controls. Transsarcolemmal I(Ca,L)and I(Na/Ca)densities, and SR Ca(2+)content were unaltered, as was membrane capacitance. A reduction in cell volume with mainteinance of internal and surface membrane areas, and/or a decrease in concentration of cellular protein Ca(2+)buffers, may contribute to the increase in the [Ca(2+)](i)transient in this model.

Relative importance of cytotoxic T lymphocytes and nitric oxide-dependent cytotoxicity in contractile dysfunction of rejecting murine cardiac allografts

BACKGROUND

Previous in vitro studies have suggested that both cytotoxic T lymphocyte (CTL)-mediated and non-CTL-mediated myocyte lysis occur during murine cardiac heterotopic allograft rejection, but the relative importance of these injury mechanisms on myocardial function is not established. We therefore compared the in vivo effects of depletion of CTL and inhibition of nitric oxide synthase (NOS) on contractility of the rejecting heart.

METHODS

Syngeneic (BALB/c into BALB/c) and allogeneic (BALB/c into C57/B16) heterotopic abdominal cardiac transplants were performed. In some of the allogeneic transplants, CD8+ lymphocytes were depleted by intraperitoneal injection of anti-CD8 monoclonal antibody. NOS inhibition was accomplished by continuous infusion of NG-monomethyl-L-arginine via a subcutaneous osmotic pump. Five days after transplantation, the abdominal cavity was opened and the transplanted heart exposed. Base to apex developed force was measured during spontaneous beating at a diastolic stretch of 4 g by placing a suture through the apex of the heart and attaching it to a strain gauge. Effects of interventions on graft survival were determined by recording the days required for loss of palpable graft contractions.

RESULTS

Allogeneic hearts showed a significant reduction in systolic force compared to non-rejecting syngeneic hearts. Depletion of CD8+ cells improved contractility significantly relative to non-depleted allogeneic hearts, but contractility remained significantly reduced relative to syngeneic hearts. Developed force in allogeneic hearts was also improved by NOS inhibition (P<0.01), and NG-monomethyl-L-arginine infusion slightly prolonged graft survival.

CONCLUSION

Both CTL-mediated and NOS-dependent (possibly macrophage-mediated) mechanisms contribute to contractile dysfunction during early cardiac allograft rejection in this model. However, NOS inhibition combined with CTL depletion only slightly prolongs graft survival in this model.

Long-term cytokine alterations following allogeneic blood transfusion

BACKGROUND

Allogeneic blood transfusion is associated with an increased risk of infection and higher cancer recurrence rates. Previous research has shown that blood transfusion results in multiple immune effects, including cytokine alterations. The purpose of this study was to measure the long term kinetics of splenocyte cytokine production in transfused mice.

METHODS

Balb/c mice received either syngeneic transfusion (Syn-BT) or allogeneic transfusion (Allo-BT) from C3H-HeN mice. Splenocyte production of IL-2, IL-6, IL-10, and IFN-gamma was quantitated by ELISA on post-transfusion days 5, 10, 21, and 30.

RESULTS

Both Allo-BT and Syn-BT produced significant alterations in cytokine production, but Allo-BT produced the most dramatic and enduring effects as summarized: IL-2: Production of IL-2 was suppressed at day 5, (p < 0.0001), but then rose, peaking at day 21, 30% greater than control values (p < 0.05). IL-6: Allo-BT mice showed suppression of IL-6 throughout the study period (p < 0.005 vs controls, each time point). IL-10: A 5-fold increase in IL-10 production was seen at day 5 after Allo-BT (p < 0.0001 vs control). Production of IL-10 was suppressed at days 10 and 21 (p < 0.001), but returned to control levels by day 30, gamma-IFN: At day 5 post Allo-BT, gamma-IFN was 4 x greater than controls (p < 0.0001). Gamma-IFN production was suppressed at day 10, but then rose at days 21 and 30 to nearly 3 x control levels (p < 0.0001).

CONCLUSION

Allo-BT produced multiple cytokine alterations that were of prolonged duration. These results provide a theoretic explanation for the multiple, long-term immunomodulating effects seen in patients who have received transfusions.

Distinct effects of allogeneic blood transfusion on splenocyte cytokine production after hemorrhagic shock

Allogeneic blood transfusion is known to be immunosuppressive in the settings of cancer and transplantation, but the contribution of blood transfusion to immunomodulation after hemorrhage is unknown. Our purpose was to determine the influence of allogeneic blood transfusion upon cytokine profiles following hemorrhagic shock, using a model which approximates the clinical setting.

METHODS

Male C3H/HeN mice were hemorrhaged via femoral arterial catheters to a mean arterial pressure (MAP) of 35 +/- 5 mm Hg, which was maintained for 1 h. Mice were resuscitated with autologous blood (auto BT) or allogeneic blood (allo BT) from Balb/c mice (both equivalent to volume of shed blood), and crystalloid (2X the volume of shed blood)-infused at 0.05 ml/min. Animals were sacrificed at 1, 2, and 5 days postshock, and splenocytes were cultured for 24 h with anti-CD3 antibody. Supernatants were assayed for IL-2, IL-6, IL-10, and gamma-IFN by ELISA.

RESULTS

Regardless of transfusion status, hemorrhagic shock resulted in increased IL-6 and gamma-IFN by Day 2 postshock. Distinct cytokine alterations after allogeneic transfusion were as follows. IL-2: transient elevation of splenocyte IL-2 production in the shock + allo BT group (P < 0.005 vs. shock + auto BT) at Postshock Day 2. IL-6: suppression in IL-6 production in the shock + allo BT group by Postshock Day 5 (P < 0.05 vs. shock + auto BT). IL-10: persistently elevated IL-10 production following shock + allo BT (Day 1, P < 0.001 vs. shock + auto BT; Day 5; P < 0.05 vs. shock + auto BT). gamma-IFN: elevation in gamma-IFN production by Day 5 in the shock + allo BT group (P < 0.0005 vs. shock + auto BT).

CONCLUSIONS

Allogeneic blood transfusion results in distinct alterations in splenocyte production of IL-2, IL-6, IL-10, and gamma-IFN after hemorrhagic shock. This model reflects the clinical usage of blood products and demonstrates some of the immune alterations after transfusion.

The 1997 Lindberg Award. Effects of burn injury on bone and growth in a mouse model

Bone growth and remodeling are inhibited by severe burns in adult and pediatric patients, resulting in alterations in linear growth, bone mass, osteoporosis, and increased risk for pathologic fractures. This study of a mouse model of burn injury showed skeletal changes similar to those reported in patients with burn injuries. Baseline, control, sham, and burned mice were injected with fluorescent markers calcein and tetracycline for histomorphometric analysis. Total femur dry and ash weights and total calcium content were significantly lower 10 days after burn injury compared with sham and control animals. There also were decreases in the percentage of fluorochrome-labeled bone surfaces and bone formation rates in the burn-injured mice compared with control and sham mice; however, there were no differences in the mineral apposition rates. This model now provides an opportunity to examine cellular and molecular mechanisms contributing to skeletal pathology in a well-defined burn injury model.

Myocardial apoptosis in a heterotopic murine heart transplantation model of chronic rejection and graft vasculopathy

BACKGROUND

Apoptosis has been implicated in myocardial reperfusion injury and in experimental transplantation rejection. One mechanism of apoptosis is through the interaction of the cell-surface Fas receptor on target cells and the Fas ligand that is expressed on cytotoxic T cells. The purpose of this study was to look for evidence of myocardial Fas receptor, Fas ligand, and apoptosis in a murine heterotopic heart transplantation model of chronic rejection/graft vasculopathy.

METHODS

Using the nick-end labeling technique, we examined a murine heterotopic heart transplantation model of chronic rejection/graft vasculopathy (strain B10.A to B10.BR) histologically for evidence of DNA fragmentation. MRNA for the Fas receptor, Fas ligand, and beta-actin was detected with reverse transcription-polymerase chain reaction.

RESULTS

Hearts harvested after 30 and 60 days showed an intimal index of the allografts (0.5 +/- 0.1) (mean +/- standard error) that was at least five times more than syngeneic grafts and native (nontransplanted) hearts (p < 0.01). In situ nick end-labeling of partially degraded DNA with terminal deoxynucleotydil transferase showed an increase in apoptotic cells in allografts and syngeneic grafts compared with native hearts. Reverse transcription-polymerase chain reaction detected equal myocardial RNA signal intensity of Fas receptor and beta-actin in allografts, syngeneic grafts, and native hearts. In contrast, allografts showed a strong signal for the Fas ligand mRNA, a signal not seen in syngeneic grafts or native hearts.

CONCLUSIONS

Apoptosis is occurring in both allografts and syngeneic grafts in this murine model of chronic rejection/graft vasculopathy, although distinct mechanisms may be involved.

Resuscitation of thermally injured patients with oxygen transport criteria as goals of therapy

Resuscitation from shock based on oxygen transport criteria has been widely used in trauma and surgical patients, but has not been examined in thermally injured patients. To study the possible efficacy of this type of resuscitation, the oxygen transport characteristics of burn resuscitation were studied in nine adults, of whom six had inhalation injuries, with a mean burn size of 45% total body surface area and a mean age of 33.4 years, who were resuscitated based on oxygen transport criteria. Pulmonary artery balloon flotation catheters were placed and hemodynamic and oxygen transport parameters (Fick method) were measured hourly for 6 hours. Patients received fluid boluses in addition to resuscitation calculated by the Parkland formula, until the pulmonary artery wedge pressure reached 15 mm Hg, after which dobutamine infusions (5 micrograms/kg/min) were initiated. Cardiac index increased from 2.51 to 6.57 L/min/m2 (p < 0.05), whereas systemic vascular resistance fell from 1534 to 584 dyne sec/cm5 (p < 0.05). Oxygen delivery (DO2I) and oxygen consumption (VO2I) indexes increased significantly during the study period (573 +/- 47 to 1028 +/- 57, and 132 +/- 8 to 172 +/- 16 ml/min/m2, respectively; p < 0.05). VO2I appeared dependent on DO2I at levels of DO2I less than 800 ml/min/m2. In this study, depressed cardiovascular function in patients with burn injuries responded to volume loading and inotropic support much as it does in patients with shock of other etiologies. Whether oxygen transport-based resuscitation is effective in improving survival or the incidence of multiple organ failure is unknown and will need to be evaluated in randomized trials.

Cytokines and rejection of mouse cardiac allografts

Graft survival is prolonged by pretransplant transfusion of the graft recipient. It has been postulated that graft rejection is associated with Th1-like cytokines. We tested whether transfusion shifts cytokine production from a Th1-type (gamma-IFN production) to a Th2-type (IL-4 production). Transfusion prolonged cardiac allograft (C3H/HeN donor to a C57BL/6 recipient) survival (10.4+/-0.5 versus 7.2+/-0.2 days for controls, P<0.0001). Splenocyte cultures from nontransfused recipients produced supernatant IFN-gamma concentrations of 13.4+/-1.4 ng/ml upon anti-CD3 stimulation; the same cells produced 32.3+/-3.5 pg/ml IL-4 stimulated with Con A. Spleen cells from transfused animals did not produce gamma-IFN with or without stimulation; (P<0.0001) and produced 21.5+/-3.2 pg/ml IL-4 without stimulation (P<0.0001 compared with controls). C57BL/6 CD8+ lymphocytes isolated from rejected C3H grafts were adoptively transferred (6.7+/-1x10(6)/animal) to pretransfused, C57BL/6 recipients of a C3H graft. Graft survival for these recipients was 7.8+/-0.3 days compared with 10.4+/-0.5 days for recipients pretreated with transfusion only (P<0.005). Transcripts of the gamma-IFN gene were present in unmodified grafts but not in the grafts from transfused recipients given the CD8 cells. In conclusion, transfusion downregulated gamma-IFN production and up-regulated IL-4 production and slowed (but did not abrogate) rejection; CD8 graft-infiltrating cells given adoptively restored normal rejection but not IFN-gamma. Further studies are needed to elucidate the role of cytokines in cardiac allograft rejection.

Melatonin and a 21-aminosteroid attenuate shock after hemorrhage but differentially affect serum cytokines

Melatonin and 21-aminosteroids (lazaroids) are potent antioxidants and may attenuate the increased membrane permeability associated with profound shock. Our purpose was to test the effect of melatonin and a lazaroid (U74389-G) on cytokine production and fluid requirements after shock.

METHODS

Male C3H/HeN mice, 20-25 g, were hemorrhaged via a femoral artery catheter to a mean arterial pressure of 35 +/- 5 mm Hg, which was maintained for 1 hr, and then resuscitated with shed blood and crystalloid (2x vol of shed blood). Experimental mice received melatonin at 10 or 50 mg/kg, U74389-G at 3 mg/kg, or vehicle i.v. upon resuscitation, and blood was returned at 0.1 cc/min and crystalloid at 0.05 cc/min. The percentage of total crystalloid required to reach stabilization (mean arterial pressure remaining within 2 mm Hg for 5 min) was recorded. Animals were sacrificed at 1 hr postshock. Serum and anti-CD3-stimulated splenocyte culture supernatants were assayed for interleukin-6 (IL-6) and gamma-IFN by ELISA.

RESULTS

Mice receiving lazaroid or melatonin (50 mg/kg) required significantly less fluid to reach stabilization, with lazaroid-treated animals requiring 24 +/- 1% and melatonin-treated animals requiring 28 +/- 2% of total crystalloid compared to 40 +/- 3% for untreated animals. Melatonin-treated mice (50 mg/kg) had lower serum IL-6 levels (368 +/- 154 vs 1078 +/- 146 pg/ml) and lazaroid-treated mice had lower gamma-IFN levels (7 +/- 6 vs 52 +/- 15 pg/ml) compared to those of the untreated group (P < 0.05). There were no differences in splenocyte cytokine production.

CONCLUSIONS

Treatment with lazaroid and melatonin both reduced postshock fluid requirements. Melatonin reduced serum IL-6 levels, while lazaroid reduced serum gamma-IFN levels, suggesting different mechanisms of action.

Return to work as a measure of outcome in adults hospitalized for acute burn treatment

Rehabilitation of patients with burn injuries is receiving renewed interest because survival has improved, and health reform has mandated outcomes assessment. To determine factors affecting return to work, a survey was conducted among 234 employed patients treated from 1986 through 1993. The mean burn size was 13.3% total body surface area. Patients returned to work in a mean of 14.3 weeks; a number initially returned to light-duty or part-time jobs as a "bridge" to full-time employment. Length of hospitalization, number of surgeries, total and full-thickness burn size, and subjective assessments by patients of their functional ability correlated with time off work. Patients with health insurance were more likely to resume work than was expected, whereas those covered by Medicaid and those involved in injury-related lawsuits were less likely to return to work. It is hoped that this information can be used to design interventions aimed at improving this outcome of burn treatment.

Influence of allogeneic blood transfusion on natural killer cell activity in burn-injured mice

Allogeneic blood transfusion (Allo/BT) and burn injury modify the cellular immune response in patients under a variety of circumstances. We designed this study to investigate the influence of Allo/BT, burn injury, and the combination of the two on in vivo natural killer (NK) cell activity in a murine model. This study demonstrated significant enhancement of in vivo NK cell activity in noninjured BALB/c mice receiving Allo/BT from C3H mice when compared to both the control and syngeneic blood transfusion group at posttransfusion day 5. When burn-injured mice were compared to sham-stressed mice, the burn-injured mice showed significant suppression of in vivo NK cell activity. Furthermore, in this strain combination model, Allo/BT modulated the suppressive effect of burn injury on in vivo NK cell activity at posttransfusion day 5 and postburn day 7.

Effects of alloimmune injury on contraction and relaxation in cultured myocytes and intact cardiac allografts

OBJECTIVES

This study was performed to determine the mechanisms by which allosensitized lymphocytes cause contractile dysfunction in cultured ventricular myocytes and to compare the effects on isolated myocytes with those observed in an intact heart preparation during allograft rejection.

BACKGROUND

Allograft rejection may be associated with reversible abnormalities of both systolic and diastolic function. The immunologic mechanisms that cause ventricular dysfunction are poorly understood.

METHODS

Vascularized heterotopic abdominal heart transplantation was performed in mice. Contractile function of excised allografts undergoing rejection was assessed using a Langendorff perfusion apparatus and a strain gauge. Spontaneously beating monolayers of cultured ventricular myocytes from donor strain fetal mice were exposed to the allosensitized cytotoxic T lymphocytes, and the effects on myocyte motion, intracellular calcium transients, relaxation half-time, membrane potential and myocyte lysis (chromium-51 release) were measured.

RESULTS

In intact hearts, histologically mild rejection without myocyte necrosis was associated with decreased systolic function without slowing of relaxation. In cultured fetal myocytes, sensitized lymphocytes induced a progressive decrease in the amplitudes of myocyte motion and calcium transients, with cessation of beating within 40 min. Also, the diastolic membrane potential and amplitude of the action potential decreased. Relaxation half-time, as estimated by measurement of cell motion, was unchanged. The effect was allospecific and was reversible with early removal of lymphocytes from the myocyte monolayer. Pretreatment of lymphocytes with the degranulation inhibitor 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene blocked both the negative inotropic effect and myocyte lysis.

CONCLUSIONS

We conclude that impaired relaxation is not a prominent feature of contractile dysfunction caused directly in myocytes by alloimmune injury from cytotoxic lymphocytes. Allosensitized lymphocytes can cause reversible systolic dysfunction in myocytes by means of a direct cell-cell interaction. This effect may be in part responsible for the reversible systolic dysfunction associated with allograft rejection.

Helper T lymphocyte unresponsiveness to cardiac allografts following transient depletion of CD4-positive cells. Implications for cellular and humoral responses

Initial treatment of heterotopic cardiac transplant recipients with anti-CD4 mAb promotes long-term (> 60 days) allograft survival. We have used modified limiting dilution analysis to quantitate donor alloantigen-reactive helper T lymphocytes (HTL) and CTL in mice bearing long-term cardiac allografts. Despite repopulation of lymphoid tissues with CD4+ T cells, donor alloantigen-reactive IL-2 producing and IL-4-producing HTL were rare or not detectable in lymphoid tissues or in the graft. While donor-reactive precursor CTL were present in lymphoid tissues, modified limiting dilution analysis revealed that stimulated ("antigen-conditioned") CTL were not detectable, and few CTL were present in the graft. In addition, antibodies reactive with donor alloantigens were not detectable in the sera of mice bearing long-term cardiac allografts. To determine whether additional in vivo stimulation with donor alloantigens would elicit an immune response, sponge allografts were implanted into mice bearing long-term cardiac allografts. Previous reports from this laboratory have demonstrated that T cell infiltration of sponge allografts is dependent upon antigen-driven cytokine production. While third-party sponge allografts were readily infiltrated by third-party-reactive HTL and CTL, sponge allografts of the same strain as the cardiac allograft were not infiltrated by T cells. However, donor strain sponge allografts induced an IgM (but not IgG) alloantibody response. These data indicate that IgM alloantibody could be induced in the absence of a cellular response to the sponge allograft. Kinetic studies revealed that a transient IgM (but not IgG) response was induced by the initial cardiac transplantation in the absence of CD4+ cells. These IgM alloantibodies disappeared by day 21 despite the persistence of the allograft. These observations indicate that transient depletion of CD4+ T cells induces allograft-specific T cell tolerance, but does not eliminate the ability to mount an allograft-specific IgM response. To our knowledge, this is the first report of a transient humoral response to alloantigens that occurs in the absence of CD4+ T cells, and can be reinduced in "tolerant" animals that fail to mount a cellular immune response. Potential mechanisms involved in the development and maintenance of anti-CD4 mAb-induced tolerance are discussed.

N omega -monomethyl-L-arginine inhibits nitric oxide production in murine cardiac allografts but does not affect graft rejection

Endogenous nitric oxide biosynthesis in mice receiving allogeneic heterotopic heart transplants was monitored as a function of time post-transplant. Nitric oxide production was measured by daily urine nitrate levels and by formation of paramagnetic heme-nitrosyl complexes in the cardiac tissue. Exogenous sources of urine nitrate and EPR signal were minimized by maintaining the animals on a low nitrite/nitrate diet. Urine nitrate peaked on postoperative day 7. A heme-nitrosyl EPR signal also appeared in the cardiac tissue on postoperative day 7 and remained unchanged in size until rejection on postoperative day 9 at which time the peak height of the signal nearly tripled. Some of the animals in the study were treated with the nitric oxide synthase inhibitor, N omega-monomethyl-L-arginine which caused marked inhibition of urinary nitrate excretion and prevented heme-nitrosyl complex formation in beating hearts. However, administration of the inhibitor did not increase graft survival time. Low intensity heme-nitrosyl signals were identified in inhibitor-treated allogeneic hearts after rejection. Syngeneic heart transplants did not induce urinary nitrate excretion nor EPR signal formation. These results show that cytokine induced high output nitric oxide synthesis from L-arginine is a prominent biochemical component of the cell-mediated immune response to cardiac allografts in mice. However, nitric oxide production was not essential for rejection of cardiac allografts mismatched at the major histocompatibility locus.

Histoincompatibility-associated differences in the phenotypes of murine cardiac allograft infiltrating T cells

Mechanisms of graft rejection may be governed in part by the kind and degree of histocompatibility differences between donor and recipient. Cardiac allograft rejection was studied in three murine models selected to provide disparity at different major histocompatibility complex (MHC), minor lymphocyte stimulating (Mls) and other minor histocompatibility loci. Graft survival for the A.TL to A.TH combination (M3) was significantly longer (median day of rejection 15.0 days) than both the B10.A to AKR (M2) or the C57BL/6 to C3H/HeN (M1) donor-recipient combinations (median days of rejection: 9.0 days and 9.0 days respectively; P < 0.001). The infiltration of grafts by T cells was examined by removal of grafts serially post-transplantation and culturing mechanically disrupted graft tissue with interleukin-2 (IL-2). Recovery of T cells by this method revealed highly reproducible characteristics (kinetic and phenotypic), unique to each donor-recipient combination. Cultures from M1 and M2 grafts had differing CD4/CD8 T-cell ratios at days 2 (1.8 versus 0.7, respectively) and 4 (1.6 versus 0.1, respectively) post-transplantation. The M3 model differed from M2 (at days 4, 8 and 10) and from M1 (at days 8 and 10). At these times, cultures of M3 grafts contained a significantly increased percentage of CD4 cells and significantly decreased percentage of CD8 cells (CD4/CD8 ratios 0.9-1.3) by comparison with M1 (CD4/CD8 ratios 0.02-0.04) and M2 (CD4/CD8 ratios 0.1-0.02). Long-surviving M3 grafts (greater than 30 days post-transplantation) were compared with grafts removed immediately upon cessation of graft function (days 14, 15 and 18 post-transplantation). There was a significant difference between these groups in the ratios of CD4/CD8 T-cell ratios (1.1 versus 0.4, respectively). This study suggests that the cellular rejection mechanism of a graft is a variable process driven by the individual histocompatibility antigen disparity between donor and recipient. These findings may have diagnostic and therapeutic applications in organ transplantation.

Immunomodulation in vivo by the Mycoplasma arthritidis superantigen, MAM

Mycoplasma arthritidis produces a potent superantigen (MAM) that activates specific murine and human T lymphocytes to proliferate and secrete lymphokines. We show here that MAM also influences both T- and B-cell functions in vivo. Lymphocytes from mice injected with MAM exhibit a suppression of proliferative responses to MAM in vitro but only a partial suppression of responses to other mitogens. This T-cell anergy not only decreased contact sensitivity to dinitrofluorobenzene but also prolonged survival of skin transplants. In contrast, B-cell reactivity is increased following in vivo injection of MAM, as evidenced by enhanced antibody responses to sheep red blood cells and ovalbumin. Also, there is a marked decrease in the ability of splenocytes from MAM-injected mice to produce interleukin-2 (IL-2) but a marked increase in their ability to produce IL-4 and IL-6. The combined results suggest that MAM induces a lymphokine profile that favors activation of B-cell functions, with a resulting potential for triggering of autoimmune disease.

Accelerated rejection of murine cardiac allografts by murine cytomegalovirus-infected recipients. Lack of haplotype specificity

Clinical studies have revealed a correlation between cytomegalovirus (CMV) infection and acute allograft rejection. Likewise, for a murine model we observed that C3H (H-2k) recipients infected with murine CMV (MCMV) rejected BALB/c (H-2d) cardiac allografts earlier than uninfected recipients (6.9 +/- 0.1 d compared with 8.1 +/- 0.6 d; P < 0.001). It has been hypothesized that MCMV epitopes crossreact with alloantigens and in this manner induce rejection. However, we also demonstrated that MCMV caused accelerated rejection in the reverse combination (C3H heart engrafted to BALB/c recipient; 7.2 +/- 0.3 and 9.4 +/- 0.4 d for infected and control animals, respectively; P < 0.001) and accelerated rejection of grafts of a third, unrelated haplotype (C57Bl/6; H-2b; 8.0 +/- 0.7 d compared with 10.1 +/- 0.6 for infected and control C3H recipients, respectively; P < 0.03). Ultraviolet (UV) inactivation of MCMV before administration to the graft recipient abrogated the ability to induce rapid rejection. Activated T lymphocytes were present in grafts from infected recipients 2 d before control recipients (P < 0.02) and, at the time of graft rejection, were almost exclusively CD8+ for both infected and control recipients. Thus, MCMV accelerated rejection appears not to result from crossreaction between MCMV epitopes and MHC products. The failure of UV-inactivated virus to accelerate rejection and the high proportion of CD8+ T cells recovered from all rejected grafts suggest that the class I pathway of antigen presentation may be important in the induction of early rejection.

Administration of dehydroepiandrosterone to burned mice preserves normal immunologic competence

Burned individuals display a reduced ability to elicit cellular and humoral immune responses and a depression in the vitro production of certain T-cell lymphokines. Treatment of burned mice with 100 micrograms of dehydroepiandrosterone within 1 hour after injury resulted in preserving a completely normal capacity to produce T-cell-derived lymphokines and to generate cellular immune responses. In addition, dehydroepiandrosterone-treated thermally injured mice demonstrated an above-normal ability to resist an induced infection with the intracellular pathogen, Listeria monocytogenes. Dehydroepiandrosterone-treated animals also did not exhibit the sustained plasma levels of interleukin 6 that normally accompany thermal injury and infection. Because of its antiglucocorticoid effects and positive immunoregulatory influences, we believe dehydroepiandrosterone to be a beneficial form of therapy for thermally injured individuals.

The effect of cyclosporine treatment on the expression of genes encoding granzyme A and perforin in the infiltrate of mouse heart transplants

Following activation of cytotoxic T cells and NK cells several genes encoding proteins putatively involved in cell-mediated cytotoxicity become expressed. The expression of genes encoding the cytotoxic T cell associated serine protease granzyme A and perforin was analyzed in cellular infiltrates of MHC mismatched (H-2d-->H-2k) heterotopic heart transplants both in immunosuppressed recipients treated with cyclosporine and in untreated recipients. Heart transplants were completely rejected by untreated animals on day 10 post-transplantation, whereas CsA treatment generally prolonged survival of the transplants beyond 30 days. In untreated recipients the number of granzyme A- and perforin-expressing cells in heart transplants increased from approximately 10 granzyme A-positive cells/mm2 and 1 perforin-positive cell/mm2 on day 2 posttransplantation to over 80 positive cells for both genes on day 5 posttransplantation. In contrast, these values remained always below 15 positive cells/mm2 for both genes between day 5 and day 30 posttransplantation in CsA-treated recipients. Comparison of the frequency of CD8+ T cells in the infiltrates showed that lower numbers of perforin and granzyme A-positive cells were mainly due to the immunosuppressive action of CsA rather than to reduced infiltration of transplants. The present study shows that expression of granzyme A and perforin gene can be used to discriminate between quiescent and activated cytotoxic cells also in immunosuppressed animals and further confirms that these can be used as sensitive markers for monitoring the fate of a transplant.

Noninvasive assessment of metabolism in wounded skin by 31P-NMR in vivo

Phosphorus-31 nuclear magnetic resonance techniques using shallow penetrating coils have been used to noninvasively monitor severity and metabolic changes over time in skin wounds in rats. Ratios of phosphocreatine (PCr) to inorganic phosphate (Pi) indicate energy status in both thermal wounds and surgical flaps. In partial and full-thickness scald wounds, reductions in PCr/Pi ratios correlated with burn depth and improved over time postinjury, suggesting wound revascularization. No decrease in intracellular pH was noted in these wounds; the phosphate shifts may be primarily the result of tissue degradation followed by restoration of the microvasculature. Distal regions of caudally based dorsal 3 x 10 cm full-thickness skin flaps reveal progressively lower PCr/Pi ratios to 3-6 hours after elevation as well as drops in pH up to 0.5 units, presumably as a result of anaerobic glycolysis in these tissues. After 24 hours, the intracellular pH returned to normal (7.1-7.2) and the PCr/Pi ratios approached 70%-90% of the well-perfused proximal regions within 3-7 days. These results indicate the establishment of a microvasculature from the underlying bed as the distal regions survive as free grafts. The data demonstrate the potential usefulness of the technique in noninvasive measurement of the biochemical response to injury and wound healing in living organisms.

Mobilization of T lymphocytes following cardiac transplantation. Evidence that CD4-positive cells are required for cytotoxic T lymphocyte activation, inflammatory endothelial development, graft infiltration, and acute allograft rejection

Modified limiting dilution analysis (LDA) techniques were used to evaluate the mobilization of antigen-stimulated helper T lymphocytes (HTL) and cytotoxic T lymphocytes (CTL) following allogeneic heterotopic cardiac transplantation. These modified LDA techniques allow a quantitative comparison of T cells that have been stimulated by antigen in vivo versus unstimulated precursor T cells of the same antigen specificity. Endothelial changes associated with mononuclear cell infiltration of the transplant were studied using endothelia-specific monoclonal antibodies and immunohistochemistry. Early (day 3) infiltration of cardiac allografts was characterized by a prevalence of donor alloantigen-specific HTL over CTL. Immunohistology revealed that the day-3 infiltrate was associated with areas of differentiated vascular endothelium, located primarily in the subepicardial region. Though donor-specific precursor HTL and CTL were present in the peripheral lymphoid tissues and blood, very few of them had been stimulated at this early time. During the latter phases of the response (days 6-9), antigen-stimulated HTL and CTL were present in the rejecting heart with CTL dominating the response. Accumulation of large numbers of donor-specific CTL in the allograft correlated with extensive inflammatory endothelial development, myocyte destruction, and loss of graft function by day 9. Stimulated HTL and CTL were detectable in peripheral lymphoid tissues at days 6 and 9. In addition, a marked increase in the number of donor-specific precursor CTL, but not precursor HTL, was observed in the lymphoid tissues at the peak of the response. Depletion of class II MHC-restricted T cells by in vivo treatment with anti-CD4 mAb eliminated HTL activity in all lymphoid compartments assessed and markedly reduced the number of CTL infiltrating the allograft. In addition, no stimulated CTL were detectable in lymphoid tissues, and the number of precursor CTL was not increased. In anti-CD4-treated recipients, cardiac allografts remained functional with minimal histological evidence of rejection for at least 21 days. Though graft-associated inflammatory endothelia were absent in anti-CD4-treated recipients at day 6, endothelial differentiation was observed in day 21 allografts in anti-CD4-treated recipients. These observations indicate that inflammatory endothelial development may precede T cell infiltration and subsequent loss of the cardiac allograft function. Thus, CD4-positive HTL are required for (1) graft-associated inflammatory endothelial development; (2) CTL activation in peripheral lymphoid tissues; (3) CTL accumulation in allografted tissues; and (4) acute cardiac allograft rejection.

Severe burn injury: effects on psychologic and immunologic function in noninjured close relatives

The crucial role of close relative care givers in the rehabilitation of the patient with burns indicates that the psychologic adjustment of noninjured relatives is of concern. This study examined the stress profiles of 14 spouses and parents of patients with burns of greater than 20% total body surface area. Four standardized measures of depression, anxiety, and cell-mediated immunity were used. Tests were given at two time intervals: less than 72 hours after admission and 2 to 5 weeks later. Depression and anxiety were high at the first test period; there was a significant drop in depression (p less than 0.05) but not in anxiety at the second testing. Immune function was suppressed at the first test but improved at the second test (p less than 0.05). There were significant negative correlations between immune response and psychologic distress, indicating that immune function declined as depressive symptoms increased. These results support an interaction between psychologic distress and immunity, and provide further evidence of the stressful nature of severe burn injury on close noninjured relatives.

Bacterial translocation is prolonged in burned mice infected with cytomegalovirus

Cytomegalovirus is seen frequently in patients with burns and may enhance morbidity and mortality rates. Burned BALB/c mice that were given murine cytomegalovirus by intraperitoneal injection demonstrate increased bacterial translocation, as evidenced by positive mesenteric lymph node culture at 5 days after burn injury. The present experiment was conducted to investigate the time course and mechanism of this effect. A significant delay in the resolution of positive mesenteric lymph node cultures was observed with thermal injury alone. This was further reduced by the addition of murine cytomegalovirus infection to thermal injury. No such delay was seen with murine cytomegalovirus infection alone or in controls.

The effect of two new immunosuppressive agents, FK506 and didemnin B, in murine pregnancy

The purpose of this study was to investigate two promising immunosuppressive agents, didemnin B (DB) and FK506 (FK), during pregnancy to assess potential adverse maternal or fetal effects. Pregnant C3H mice were randomized into control and high- and low-dose treatment groups for each drug. Animals received daily injections from day 1 to day 16, and on day 17 of gestation the maternal condition, litter size, fetal resorption rates, and fetal/placental unit weights were determined. Immunoglobulin (IgG) levels were obtained for DB treatment groups. Delayed type hypersensitivity was assessed in virgin females. Both DB and FK had dose-dependent immunosuppressive activity in the DTH assay, and DB caused elevated IgG concentrations. High doses of DB caused diarrhea and maternal wasting with no fetal survival; with low-dose DB, maternal weight gain was depressed, but pregnancy outcome was not different from control animals. High-dose FK had no obvious detrimental effects on maternal health but caused resorption of all fetuses; administration of low-dose FK resulted in a higher number of resorptions, but fetuses that survived did not appear different from controls. We conclude that these immunosuppressive drugs can have adverse effects on pregnancy, but the maternal and fetal toxicity are dose-dependent.

Intraperitoneal sensitization and the transplanted mouse heart

Intradermal or skin-graft sensitization always results in accelerated rejection of subsequent MHC-disparate mouse heart transplants; intravenous or intrasplenic sensitization almost always results in prolonged survival. The survival time after intraperitoneal sensitization is unpredictable: hyperacute or accelerated rejection, as well as normal or prolonged survival, occurs suggestive of a delicate balance between suppressive and rejecting immune responses. We have observed a positive correlation between transplant survival and the distribution of 51Cr-labeled antigenic cells early after i.v., i.d., i.p., and intrasplenic injection. Label recovery from the viscera was already high 2 hr after i.v. injection, while after i.d. injection virtually all label was still confined to the carcass, even at the end of a 24-hr period. After i.p. injection label recovery varied significantly from mouse to mouse, from very low to a level approximating that seen after i.v. injection. This close correlation suggests that the fate of a subsequent transplant is decided within a few hours after antigen deposition, well before placement of the transplant itself.

Myocyte injury and contraction abnormalities produced by cytotoxic T lymphocytes

BACKGROUND

The mechanisms by which ventricular function is altered during cardiac transplant rejection are not well understood. Therefore, an in vitro model system has been developed to facilitate investigation of lymphocyte-mediated myocyte injury.

METHODS AND RESULTS

Splenic lymphoid cells were obtained from mice 8-10 days after placement of a vascularized abdominal cardiac allograft and were restimulated in vitro with irradiated donor-type splenocytes for 5 days. Cytotoxic effects of these allogenically stimulated lymphocytes on syngeneic and donor strain fetal cultured myocytes were determined by a 51Cr release assay at different lymphocyte to myocyte ratios. 51Cr release from donor strain myocytes was detectable within 1 hour of exposure, was maximal by 3-5 hours of coincubation with sensitized lymphocytes, and was allospecific. Cell injury manifest by 51Cr release was calcium dependent and was inhibited by pretreatment of lymphocytes with phorbol ester to deplete protein kinase C. Myocyte injury was also prevented by pretreatment of sensitized lymphocytes with anti-Thy 1.2 or anti-CD8 antibody plus complement but not by treatment with anti-CD4 antibody, indicating that CD8+ cytotoxic T cells are involved. Altered myocyte contractile motion preceded myocyte lysis (51Cr release), was characterized by an initial reversible decrease in amplitude of contraction, and was followed by rapid and irregular beating with eventual complete cessation of contraction. Contractile alterations induced by sensitized lymphocytes were inhibited by elimination of CD8+ cells.

CONCLUSIONS

Myocyte injury can be produced by sensitized cytotoxic T lymphocytes in vitro and is calcium and protein kinase C dependent. The contractile abnormalities produced appear to be similar to those observed in cardiac transplant patients undergoing rejection, and thus this model system promises to allow investigation of the mechanisms involved.

The slotted crossover surface coil: a detector for in vivo NMR of skin

An elongated, narrow, slotted crossover surface coil provides surface localization capable of resolving in vivo 31P NMR spectra from skin tissues. The shallow B1 field penetration achieves localization objectives while the probe length maintains signal-to-noise requirements. Dielectric and inductive losses are minimized via the crossover design (see T. L. Nagel et al., Magn. Reson. Med. 13, xxx (1990). In vivo spectra with millimeter depth resolution were acquired in 5 min at 2 T without pulse localization sequences. Preliminary 31P NMR spectra of normal and thermally injured rat skin were completed using a 25 X 3-mm slotted probe with a 3 X 2-cm surface region of excitation. Normal rat skin tissue PCr/Pi ratios ranged from 3.8 to 4.7 for 5-, 10-, and 30-mus pulse widths, while partial- and full-thickness scald injured tissues ranged from 0 to 2.8. Evaluation of a single minor partial thickness injury 1 to 5 h postburn shows evidence of a localized hypermetabolic response associated with hyperemia. Determination of burn depth and tissue viability appears feasible using: (1) PCr/Pi ratios and (2) observation of localized hypermetabolism.

Cytomegalovirus infection promotes bacterial translocation in thermally injured mice

Thermally injured mice that were given intraperitoneal injections of murine cytomegalovirus (MCMV) appeared to be clinically septic and to have increased mortality rates. To evaluate the possible role of MCMV infection in promoting bacterial translocation in burned mice, mesenteric lymph nodes were cultured from two strains of mice (BALB/c and CBA) that were given thermal injuries alone, MCMV alone, or both. BALB/c mice injected with 5 X 10(5) plaque-forming units MCMV following a 15% to 16% total body surface area scald injury had increased incidence of positive mesenteric lymph node cultures compared with other groups. No intestinal mucosal histologies, mucosal dry weights, or wet-to-dry weight ratios in any animals were abnormal. Differences in cecal bacterial concentrations were not observed. Murine cytomegalovirus infection appears to enhance bacterial translocation in this model.

The continuing challenge of burn care in the elderly

Recent improvements in survival have stimulated interest in the care of elderly patients with burn injuries. We reviewed 278 patients aged 45 years and older treated during a 10-year period. The survival rate was 80% overall and 67% for patients over 75 years of age. Mortality rates correlated with patient age, burn size, presence of inhalation injury, number of complications of care, and fluid resuscitation requirements, but not with the number of preexisting medical problems. Burn wound excision and skin grafting were performed frequently and were well tolerated. During this period, hospital charges increased fourfold and were twice as great in nonsurvivors. Reimbursements based on diagnosis-related groups during the last 3 years of the review (75 patients) resulted in a total deficit of $1.2 million. Aggressive care for most elderly patients with burn injuries appears justified by the improved outcomes demonstrated. This has increased the difficulty of decisions regarding patient salvability and the allotment of resources. Elderly patients with burn injuries illustrate many contemporary dilemmas in patient care in this era of cost consciousness.

Naloxone inhibits the in vivo immunosuppressive effects of morphine and thermal injury in mice

The effect of opioids (both exogenous and endogenous) on cell-mediated immune response in normal and thermally injured mice was evaluated with a delayed-type hypersensitivity assay. The administration of morphine sulfate to normal mice resulted in decreased delayed-type hypersensitivity response. This morphine sulfate-induced immunosuppression was prevented by concurrent treatment with the opioid antagonist, naloxone; however, naloxone alone did not alter immune response. Thermally injured mice had a suppressed delayed-type hypersensitivity response that was not further affected by morphine sulfate administration. In contrast, the immunosuppressive effects caused by burn injury, alone or in combination with the administration of morphine sulfate, were not observed in the presence of naloxone as measured by delayed-type hypersensitivity response. These results suggest that opioids depress cellular immune response and may play a role in immune dysfunction that follows thermal injury.

Hyperacute rejection of the transplanted mouse heart

Mouse hearts transplanted heterotopically to MHC-disparate recipients can be hyperacutely rejected (HAR) after a single or 3 sequential donor type skin grafts, or a single intradermal injection of lymphoid cells. In the combinations tested, not all hearts are HAR; most of them are rejected in accelerated fashion. Our results with transplanted rat hearts are similar, even in a genetic combination for which HAR of all hearts has been reported. However, in rats, HAR tends to occur more rapidly and to be associated with more-intense vascular changes. Transfer of serum from mice or rats sensitized by 3 sequential skin grafts likewise resulted in occasional hyperacute but never accelerated rejection. Transfer of lymph node cells from mice sensitized with a single skin graft always resulted in accelerated but never in hyperacute rejection; transfer of cells after 3 sequential skin grafts caused neither accelerated nor hyperacute rejection.

Effect of ibuprofen and interleukin 2 on transfusion-induced suppression of cell-mediated immunity

Transfusion-induced immunosuppression has been associated with excessive production of prostaglandin E and decreased interleukin 2 (IL-2) production. In the present study, allogeneic blood-transfused mice were tested for cell-mediated immunity with the use of a delayed-type hypersensitivity assay. In vivo administration of a cyclo-oxygenase inhibitor, ibuprofen, and murine recombinant IL-2 was initiated on day 0 and continued daily throughout the delayed-type hypersensitivity assay. The results indicate that prostaglandin E may play a primary role in allogeneic blood transfusion-induced suppression, as manifest by normal responses in ibuprofen-treated mice. Supplementation of transfused mice with recombinant IL-2 also preserved immune response, indicating inadequate IL-2 production after transfusion, while receptor expression appears to remain intact.