Preformed IgG antibodies against major histocompatibility complex class II antigens are major risk factors for high-grade cellular rejection in recipients of heart transplantation

Transitory immunologic response after implantation of the DeBakey VAD continuous-axial-flow pump

BACKGROUND

The development of local and systemic infection is a significant risk factor associated with implantation of a ventricular assist device. The immunologic consequence of continuous-flow rotary blood pumps is not known.

METHODS

Six male adult patients (mean age 47 plus minus 10.3) with end-stage left heart failure received a DeBakey VAD axial-flow pump for use as a bridge to transplantation. (Four patients underwent transplantation after a mean 115 plus minus 14 days; 2 patients are still waiting for the allograft.)

RESULTS

We prospectively monitored T-cell populations and apoptosis-specific aberrant T-cell activation via CD95 triggering and annexin V binding to lymphocytes, identifying T cells undergoing early phases of apoptosis, within the first 10 weeks. Moreover, soluble death-inducing receptors soluble CD95 and soluble tumor necrosis factor-R1 were evaluated by enzyme-linked immunosorbent assay.

CONCLUSION

Patients bridged to transplantation by a nonpulsatile ventricular assist device demonstrated an initial pronounced apoptosis-specific immune alteration by increased annexin V binding to CD3 T cells and death-inducing receptors soluble CD95/tumor necrosis factor-R1 (all P <.001). All parameters normalized after 7 weeks to baseline. No blood-borne sepsis was detected, as defined by blood culture, within the first 10 weeks of the cohort study. These results indicate a biphasic immunologic response in patients with end-stage heart failure treated with nonpulsatile ventricular assist devices.

Preformed anti-human leukocyte antigen antibodies jeopardize cardiac transplantation in patients with a left ventricular assist device

In 1997, 15% of patients who received a cardiac transplant in the United States needed a mechanical circulatory support device before transplantation. One device that patients received was the left ventricular assist device (LVAD). During the LVAD support period, approximately 30% to 80% of LVAD recipients have positive test results for panel reactive antibodies (PRAs). Many of these antibodies form against human leukocyte antigens (HLA). These antigens are present on most cells and stimulate antibody production when a person receives unrelated donor cells. Several pre-LVAD and post-LVAD factors contribute to anti-HLA antibody formation. These antibody levels must be lowered before transplantation because the presence of anti-HLA antibodies makes it more difficult to find a suitable donor and increases the risk of rejection. The objectives of this article are to describe anti-HLA antibody formation in LVAD recipients, review its major consequences and treatments, and discuss nursing actions associated with anti-HLA antibody formation.

Development of anti-major histocompatibility complex class I or II antibodies following left ventricular assist device implantation: effects on subsequent allograft rejection and survival

BACKGROUND

Previous reports have indicated that antibodies to HLA class I or II antigens develop in approximately 60% of patients following left ventricular assist device (LVAD) implantation, subsequent rates of allograft rejection are higher, and survival is adversely affected.

METHODS

We performed an analysis of the incidence of antibody development to HLA class I or II antigens by panel reactive antibody (PRA) screening following implantation of the HeartMate LVAD in 38 patients from October 1, 1996 to March 1, 2000 (6 LVAD deaths excluded from study). The occurrence of vascular or cellular rejection of International Society of Heart and Lung Transplantation grade > or = 3A, as determined by endomyocardial biopsy following heart transplantation (HTX), were compared for patients with (n = 32, LVAD group) or without (n = 68, control group) preoperative LVAD support.

RESULTS

After LVAD implantation, 9 patients (28%) in the LVAD group developed IgG antibodies to class I (n = 3), class II (n = 5), or both antigens (n = 1) with PRA > 10%. The remaining 23 patients (72%) had either no detectable IgG antibody development or IgG antibody development with PRA < 10%. At the time of HTX, only 4 patients in the LVAD group had persistent PRA > 10%. Only 3 patients (4%) in the control group had PRA > 10% at the time of HTX. The incidence of patients free from rejection at 6 and 12 months was 62% and 44% for the control group, and 49%, and 40% for the LVAD group, respectively (p not significant). The mean linearized rate plus or minus standard deviation of allograft rejection from 0 to 6 months and 7 to 12 months was 0.13 +/- 0.21 and 0.09 +/- 0.14 episodes a month, respectively, for patients with no LVAD support, and 0.17 +/-.25 and 0.06 +/- 0.1 episodes a month, respectively, for those with LVAD support (p = not significant). Post-transplantation survival at 1 and 2 years was 90% and 90%, respectively, for the control group, and 97% and 92%, respectively, for the LVAD group (p not significant).

CONCLUSION

Patients with LVAD support before HTX do not appear to be at increased risk for significant allograft rejection in the first year or for death within the first 2 years after transplantation.

Flow cytometric detection of HLA-specific antibodies as a predictor of heart allograft rejection

BACKGROUND

Historically, panel reactive antibody (PRA) analysis to detect HLA antibodies has been performed using cell-based complement-dependent cytotoxicity (CDC) techniques. Recently, a flow cytometric procedure (FlowPRA) was introduced as an alternative approach to detect HLA antibodies. The flow methodology, using a solid phase matrix to which soluble HLA class I or class II antigens are attached is significantly more sensitive than CDC assays. However, the clinical relevance of antibodies detected exclusively by FlowPRAhas not been established. In this study of cardiac allograft recipients, FlowPRA was performed on pretransplant sera with no detectable PRA activity as assessed by CDC assays. FlowPRA antibody activity was then correlated with clinical outcome.

METHODS

PRA analysis by anti-human globulin enhanced (AHG) CDC and FlowPRA was performed on sera corresponding to final cross-match specimens from 219 cardiac allograft recipients. In addition, sera collected 3-6 months posttransplant from 91 patients were evaluated. The presence or absence of antibodies was correlated with episodes of rejection and patient survival. A rejection episode was considered to have occurred based on treatment with antirejection medication and/or histology.

RESULTS

By CDC, 12 patients (5.5%) had pretransplant PRA >10%. In contrast, 72 patients (32.9%) had pretransplant anti-HLA antibodies detectable by FlowPRA (34 patients with only class I antibodies; 7 patients with only class II antibodies; 31 patients with both class I and class II antibodies). A highly significant association (P<0.001) was observed between pretransplant HLA antibodies detected by FlowPRA and episodes of rejection that occurred during the first posttransplant year. Fifteen patients died within the first year posttransplant. Of nine retrospective flow cytometric cross-matches that were performed, two were in recipients who had no pretransplant antibodies detectable by FlowPRA. Both of these cross-matches were negative. In contrast, five of seven cross-matches were positive among recipients who had FlowPRA detectable pretransplant antibodies. Posttransplant serum specimens from 91 patients were also assessed for antibodies by FlowPRA. Among this group, 58 patients had FlowPRA antibodies and there was a trend (although not statistically significant) for a biopsy documented episode of rejection to have occurred among patients with these antibodies.

CONCLUSIONS

Collectively, our data suggest that pre- and posttransplant HLA antibodies detectable by FlowPRA and not AHG-CDC identify cardiac allograft recipients at risk for rejection. Furthermore, a positive donor reactive flow cytometric cross-match is significantly associated with graft loss. Thus, we believe that detection and identification of HLA-specific antibodies can be used to stratify patients into high and low risk categories. An important observation of this study is that in the majority of donor:recipient pairs, pretransplant HLA antibodies were not directed against donor antigens. We speculate that these non-donor-directed antibodies are surrogate markers that correspond to previous T cell activation. Thus, the rejection episodes that occur in these patients are in response to donor-derived MHC peptides that share cryptic determinants with the HLA antigens that initially sensitized the patient.

Impact of current management practices on early and late death in more than 500 consecutive cardiac transplant recipients

OBJECTIVE

To study risk factors for early and late death after heart transplantation in the current era.

SUMMARY BACKGROUND DATA

The current cardiac transplant population differs from earlier periods in that an increasing number of sicker patients, such as those with ventricular assist device (LVAD) support, prior cardiac allotransplantation, and pulmonary hypertension, are undergoing transplantation. In addition, sensitized patients constitute a greater proportion of the transplanted population. Emphasis has been placed on therapies to prevent early graft loss, such as the use of nitric oxide and improved immunosuppression, in addition to newer therapies.

METHODS

Five hundred thirty-six patients undergoing heart transplantation between 1993 and 1999 at a single center were evaluated (464 adults and 72 children; 109 had received prior LVAD support and 24 underwent retransplantation). The mean patient age at transplantation was 44.9 years. Logistic regression and Cox proportional hazard models were used to evaluate the following risk factors on survival: donor and recipient demographics, ischemic time, LVAD, retransplantation, pretransplant pulmonary vascular resistance, and immunologic variables (ABO, HLA matching, and pretransplant anti-HLA antibodies).

RESULTS

The rate of early death (less than 30 days) was 8.5% in adults and 8.8% in children. The actuarial survival rate of the 536 patients was 83%, 77%, and 71% at 1, 3, and 5 years, respectively, by Kaplan Meier analysis. Risk factors adversely affecting survival included the year of transplant, donor age, and donor-recipient gender mismatching. Neither early nor late death was influenced by elevated pulmonary vascular resistance, sensitization, prior LVAD support, or prior cardiac allotransplantation.

CONCLUSIONS

Previously identified risk factors did not adversely affect short- or long-term survival of heart transplant recipients in the current era. The steady improvement in survival during this period argues that advances in transplantation have offset the increasing acuity of transplant recipients.

Immunobiology of left ventricular assist devices

The increasing use of implanted biomaterial devices has made it evident that no material is biologically inert. As a result of direct contact with elements of the blood circulation, such as during hemodialysis or after left ventricular assist device (LVAD) implantation, significant changes in systemic immunologic and thrombostatic functions occur. The clinical success of LVAD implantation has, nevertheless, been accompanied by complications arising from an aberrant state of monocyte and T-cell activation, leading to heightened susceptibility of circulating CD4 T cells to undergo activation-induced cell death; this results in progressive defects in cellular immunity and an increased risk of serious infection. Because of the increased state of T-cell activation and the selective loss of Th1 cytokine producing CD4 T cells, LVAD recipients also develop B-cell hyperreactivity and dysregulated immunoglobulin syntheses by unopposed production of Th2 cytokines and increased CD40 Ligand-CD40 interactions. LVADs are currently being evaluated as a permanent therapy for end-stage heart failure. Because these immune dysfunctions appear to be related to the effects of excessive biomaterial associated T-cell activation, future efforts will need to be directed at either altering the physical properties of the materials interacting with the host circulation or pharmacological intervention aimed at inhibiting T-cell activation.

Preoperative assessment and management of pediatric heart transplantation

The period of preoperative management of the pediatric cardiac transplant patient can be divided into three phases: determination of transplant feasibility, listing, and medical management. Chronic infection, irreversible elevation of pulmonary vascular resistance, and intractable disease in other organ systems may all be contraindications for transplantation. The United Network for Organ Sharing has recently changed its listing guidelines. Adolescent donors are now preferentially, to some extent, allocated to adolescent recipients. Management of pediatric patients awaiting cardiac transplantation encompasses optimization of cardiac output through the use of vasodilators and oral and intravenous inotropic agents. For those patients listed for transplantation who have single ventricle lesions, such as hypoplastic left heart syndrome, management of heart failure also includes balancing systemic and pulmonary blood flows. Mechanical support of the circulation with extracorporeal membrane oxygenation or ventricular assist devices can be used as a bridge to transplant in pediatric patients.

Clinico-pathologic, immunohistochemical, and TUNEL study in early cardiac allograft failure

Early cardiac allograft failure (ECAF) was defined as acute allograft failure in the early transplant period. The aim of this study is to elucidate the clinicopathological and immunohistochemical characteristics and the role of apoptosis in ECAF in nine patients. We reviewed preoperative clinical data and morphological data at the time of autopsy or retransplantation. We also performed TUNEL assay and immunohistochemistry to study fibronectin and tubulin beta-II. The average recipient and donor age was 48 +/- 10.3 and 28 +/- 7.11 respectively. Seven patients died at a mean time of 26 hours. The remaining two patients underwent retransplantation and are alive. The mean cold ischemic time was 124. 1 +/- 44.5 minutes. No patient had a panel reactive antibody >15% and lymphocytic crossmatch was positive in one case. All cases had grade 2-3 of coagulative necrosis, which correlated positively with fibonectin accumulation in myocyte cytoplasm, and cytoplasmic tubulin loss (p < 0.05). TUNEL technique showed in all cases some degree of DNA strand breaks in cardiomyocytes. Endothelium DNA strand breaks were seen in seven cases. Patients transplanted because of idiopathic dilated cardiomyopathy had a significantly higher degree of DNA strand breaks in cardiomyocytes and endothelial cells (p = 0.03 and p = 0.02) than those transplanted because of ischemic cardiomyopathy. These results indicate that ECAF may be caused by ischemic-reperfusion damage to the donor heart assessed by myocyte coagulative necrosis, fibronectin accumulation in myocytes, tubulin loss, and DNA strand breaks of cardiomyocytes and endothelium. The use of a combination of these techniques might be appropriate in the diagnosis of ECAF in endomyocardial biopsies when it is suspected clinically.

Aortic regurgitation: quantitative methods by echocardiography

Quantification of aortic regurgitation (AR) is a common and difficult clinical problem. The severity of regurgitation has traditionally been estimated with the use of contrast aortography, which is impractical as a screening tool or for serial examinations. In the past two decades, Doppler echocardiography has emerged as an important tool in the quantification of AR. Pulsed Doppler mapping of the depth of the regurgitant jet into the left ventricle was one of the initial echocardiographic methods used for this purpose. The slope and pressure (or velocity) half-time of continuous-wave Doppler profiles of regurgitant jets are also useful. These Doppler techniques may be used to determine the regurgitant volume or regurgitant fraction in patients with AR. The use of color Doppler to measure the height (or cross-sectional area) of the regurgitant jet relative to the height (cross-sectional area) of the left ventricular outflow tract is both sensitive and specific in the quantification of AR. More recently, the continuity principle has been used to determine the effective aortic regurgitant orifice area, which increases as AR becomes more severe. Although this is a promising tool, calculation of this value is not yet common practice in most echocardiography laboratories. Although no single echocardiographic technique is without limitations, all have some validity, and it is reasonable to use a combination of them to obtain a composite estimate of the severity of AR.

Detection of anti-HLA antibody by flow cytometry in patients with a left ventricular assist device is associated with early rejection following heart transplantation

BACKGROUND

Patients with a left ventricular assist device (LVAD) as a bridge to heart transplantation (HT) often have elevated levels of panel reactive antibodies (PRA). The clinical significance of anti-human histocompatibility leukocyte antigen (HLA) antibodies detected by flow cytometry in PRA negative patients remains unclear.

METHODS

Eighteen patients who underwent LVAD placement as a successful bridge to HT had standard anti-human globulin complement-dependent cytotoxicity and retrospective flow cytometry assays performed to detect class I anti-HLA antibodies. A positive flow result was defined as a fluorescent ratio of 23:1 versus a negative control.

RESULTS

Six patients had anti-HLA antibodies detected by flow cytometry. Univariate analysis demonstrated more moderate-severe rejection episodes (ISHLT > or = IIIA) at 2 months (0.83+/-0.75 vs. 0; P=0.04) and a trend toward decreased time to first rejection (61+/-17 vs. 225+/-62 days; P=0.06) in these patients. No differences were observed in donor-recipient HLA mismatch or 1 year Kaplan-Meier survival between patients with or without anti-HLA antibodies.

CONCLUSION

Despite a negative PRA, LVAD patients with class I anti-HLA antibodies detected by flow cytometry have a greater incidence of moderate-severe rejection in the first 2 months after HT. Flow cytometry may be a useful clinical tool in screening PRA negative LVAD patients before transplantation. Patients with positive anti-HLA antibody screening by flow cytometry may require more intensive immunosuppression in the early post-HT period.

Posttransplantation cytotoxic immunoglobulin G is associated with a high rate of acute allograft dysfunctions in heart transplant recipients

BACKGROUND

The significance of anti-human leukocyte antigen immunoglobin G (IgG) detected in the posttransplantation course of heart graft recipients remains unclear.

METHOD

Sera from 121 cardiac allograft recipients transplanted between January 1992 and December 1994 were screened for the presence of lymphocytotoxic antibodies in the first year after transplantation. Dithiothreitol was used to differentiate IgG from immunoglobulin M.

RESULTS

Nineteen patients (15%) had cytotoxic IgG develop, mainly during the first month after transplantation. The percentage of women was higher in this group (42% vs 15.7%; P <.05). Donor to recipient mismatches for sex, blood typing, cytomegalovirus serology, and human leukocyte antigen typing were comparable between IgG producers and nonproducers. The frequency of acute allograft dysfunction during the first year after transplantation was significantly higher among patients producing IgG (42% vs 5.9; P <.001). Most of these acute allograft dysfunctions were independent of cellular rejection lesions but were associated with a thickening of the posterior wall and the interventricular septum during the acute episode. Finally, all the patients but one recovered. Recurrences were not uncommon and, at 1 year after transplantation, the dose of cyclosporine used in patients producing IgG was significantly greater, as was the left ventricular thickness.

CONCLUSION

Posttransplantation cytotoxic IgG is not uncommon and appears to be associated with a high rate of acute allograft dysfunction. Development of these antibodies can be caused by a previous undetected immunization, as suggested by the higher percentage of women in the producer group. Correlation with histologic lesions of humoral rejection are discussed.

Detection of humoral rejection in human cardiac allografts by assessing the capillary deposition of complement fragment C4d in endomyocardial biopsies

BACKGROUND

There are no well-established diagnostic criteria to detect humoral rejection in organ transplantation. The value of commonly used markers in immunohistochemistry, such as C1q, C3c, IgG, IgM and fibrinogen, is questioned by some groups. Complement fragment C4d is a more stable marker of complement activation as it is covalently bound to graft capillaries. C4d has been shown to identify clinically relevant, but otherwise undetectable humoral anti-graft reactions in human kidney transplants.

METHODS

Immunohistochemical techniques were used to evaluate 155 endomyocardial biopsies from 56 heart transplant recipients less than 3 months post transplantation for the presence of capillary C4d staining. In a subset of patients, C4d staining was compared with C1q, C3c, IgM and fibrin staining and was correlated with clinical outcome.

RESULTS

Within 3 months 9 of 56 patients died. Five of these nonsurvivors had prominent C4d staining (p < .05), whereas C1q, C3c and IgM showed no correlation with clinical outcome. Presence of fibrin correlated with clinical outcome and C4d staining (p < .05).

CONCLUSIONS

The capillary deposition of complement split product C4d in human endomyocardial biopsies was significantly associated with graft loss. Determination of fibrin deposition may yield additional information to establish a diagnosis of humoral rejection. The immunohistochemical assessment of capillary deposition of C4d and fibrin appears to be an appropriate tool for the identification of patients, who may require additional or alternative immunosuppressive therapy targeted against the humoral immune system.

Activation-induced T-cell death and immune dysfunction after implantation of left-ventricular assist device

BACKGROUND

Cardiac transplantation is a limited option for end-stage heart failure because of the shortage of donor organs. Left-ventricular assist devices (LVADs) are currently under investigation as permanent therapy for end-stage heart failure, but long-term successful device implantation is limited because of a high rate of serious infections. To examine the relation between LVAD-related infection and host immunity, we investigated immune responses in LVAD recipients.

METHODS

We compared the rate of candidal infection in 78 patients with New York Heart Association class IV heart failure who received either an LVAD (n=40) or medical management (controls, n=38). Fluorochrome-labelled monoclonal antibodies were used in analyses of T-cell phenotype. Analysis of T-cell function included intradermal responses to recall antigens and proliferative responses after stimulation by phytohaemagglutinin, monoclonal antibodies to CD3, and mixed lymphocyte culture. We measured T-cell apoptosis in vivo by annexin V binding, and confirmed the result by assessment of DNA fragmentation. Activation-induced T-cell death was measured after T-cell stimulation with antibodies to CD3. All immunological tests were done at least 1 month after LVAD implantation. Between-group comparisons were by Kaplan-Meier actuarial analysis and Student's t test.

FINDINGS

By 3 months after implantation of LVAD, the risk of developing candidal infection was 28% in LVAD recipients, compared with 3% in controls (p=0.003). LVAD recipients had cutaneous anergy to recall antigens and lower (<70%) T-cell proliferative responses than controls after activation via the T-cell receptor complex (p<0.001). T cells from LVAD recipients had higher surface expression of CD95 (Fas) (p<0.001) and a higher rate of spontaneous apoptosis (p<0.001) than controls. Moreover, after stimulation with antibodies to CD3, CD4 T-cell death increased by 3.2-fold in LVAD recipients compared with only 1.2-fold in controls (p<0.05).

INTERPRETATION

LVAD implantation results in an aberrant state of T-cell activation, heightened susceptibility of CD4 T cells to activation-induced cell death, progressive defects in cellular immunity, and increased risk of opportunistic infection.

Long-term survival after cardiac retransplantation: a twenty-year single-center experience

OBJECTIVE

To identify risk factors for survival after cardiac retransplantation and compare the survival after retransplantation with that after primary cardiac transplantation.

METHODS

A retrospective analysis of 952 patients undergoing cardiac transplantation for the treatment of end-stage heart disease at a single center between 1977 and October 1997. Of these, 43 patients (4.5%) underwent cardiac retransplantation for cardiac failure resulting from transplant-related coronary artery disease, rejection, and early graft failure.

RESULTS

No significant difference in actuarial patient survival was found by Kaplan-Meier analysis at 1, 2, and 5 years between patients undergoing primary transplantation and those undergoing retransplantation 76%, 71%, and 60% versus 66%, 66%, and 51%, respectively (P =.2). Multivariable analysis identified a shorter interval between transplants and an initial diagnosis of ischemic cardiomyopathy as significant risk factors for death after retransplantation (P =.04 and.03, respectively). Since 1993, when our criteria for patient selection for retransplantation were revised on the basis of earlier experience to exclude patients with allograft dysfunction as a result of primary graft failure and those with intractable acute rejection occurring less than 6 months after transplantation, the survival has been significantly better (<1993 = 45%, 45%, and 33% versus >/=1993 = 94%, 94%, and 94% at 1, 2, and 4 years, respectively, P =.003).

CONCLUSION

The long-term outcome of cardiac retransplantation is comparable with that of primary transplantation, especially in patients with transplant-related coronary artery disease. Patient characteristics and other preoperative variables should assist in the rational application of retransplantation to ensure optimal use of donor organs.

An immunological algorithm to predict risk of high-grade rejection in cardiac transplant recipients

BACKGROUND

Transplant-related coronary-artery disease (TCAD) develops frequently in cardiac-allograft recipients, and limits long-term survival. We examined the relation between this disorder and cumulative frequency of high-grade rejection, and investigated whether concomitant use of three immunological factors at the time of a low-grade endomyocardial biopsy can predict progression to high-grade rejection.

METHODS

We investigated the relation between the cumulative annual frequency of high-grade rejection and TCAD in 198 recipients of cardiac transplantation between 1992 and 1996 by means of Kaplan-Meier actuarial life-tables. Endomyocardial biopsy, lymphocyte-growth assays, and anti-HLA antibody measurements were compiled over 12 months in 102 patients during their first post-transplant year. We calculated predictive values for high-grade rejection within 90 days by chi2, Kaplan Meier survival curves, and by multivariable logistic regression analyses.

FINDINGS

We found a direct correlation between cumulative annual frequency of rejection and TCAD onset with highest risk in those with more than 0.75 rejections per year (p=0.0002). After a low-grade endomyocardial biopsy (0 or 1A), one or more donor-recipient HLA-DR matches protected against high-grade rejections (p<0.001). Among individuals with one or two DR matches, the negative predictive value for progression from a low-grade biopsy to a high-grade rejection was 87% in the presence of a negative lymphocyte-growth assay. Among individuals with no DR matches, the presence of either a positive lymphocyte-growth assay or IgG anti-major-histocompatibility complex (MHC) class II antibodies was independently associated with high probability of progression to rejection (64% and 66%, respectively, p<0.0005). When both assays were positive, concomitantly with a low-grade endomyocardial biopsy, the positive predictive value for progression to a high-grade rejection was 86% (p<0.0001). For endomyocardial-biopsy grades 1B or 2, a positive lymphocyte-growth assay alone was associated with high-grade rejection in 100% of cases.

INTERPRETATION

Use of an algorithm combining three immunological factors at the time of a low-grade endomyocardial biopsy enables prospective stratification of cardiac transplant recipients into risk categories for progression to high-grade rejection. Low-risk individuals require fewer biopsies, moderate-risk individuals require an ongoing schedule of surveillance biopsies, and high-risk individuals require rational organisation of interventional strategies aimed at preventing rejection. Additional predictive factors are needed to identify moderate-risk individuals who will progress to rejection. Ultimately, successful intervention may have an impact on the subsequent complication of TCAD.