Protein I/II of oral viridans streptococci increases expression of adhesion molecules on endothelial cells and promotes transendothelial migration of neutrophils in vitro

As accumulation of leukocytes in perivascular tissues is a key step in inflammatory disorders, we have analyzed in the present work the up-regulation of expression of adhesion molecules, such as E-selectin, ICAM-1, and VCAM-1, on human endothelial cells, in response to protein I/II, a modulin from Streptococcus mutans OMZ 175. Using cultured human saphenous vein endothelial cells (HSVEC), we demonstrated that protein I/II directly and specifically up-regulated E-selectin, ICAM-1, and VCAM-1 expression. We confirmed also that the up-regulation of adhesion molecules in HSVEC is mediated by lectin activity for NANA- and fucose-containing receptors. The ability of protein I/II to promote the transendothelial migration of neutrophils was then examined. Using Transwell inserts, we found that protein I/II, in promoting the up-regulation of adhesion molecule expression, stimulates neutrophil migration through endothelial cells. These events may play a role in the etiology of inflammatory responses leading to the various pathologies associated with oral viridans streptococci.

The A and the extended V N-terminal regions of streptococcal protein I/IIf mediate the production of tumour necrosis factor alpha in the monocyte cell line THP-1

The induction of tumour necrosis factor (TNF)-alpha from the monocytic cell line THP-1 by the streptococcal antigen I/II from Streptococcus mutans serotype f (protein I/IIf) was studied by use of recombinant polypeptides containing the discrete domains of the protein. The derivatives carrying the N-terminal alanine-rich region (A region) and the adjacent variable region (extended V region) of the protein bound to THP-1 cell extracts in a saturable fashion, and one derivative lacking both the A and the extended V regions was not able to bind monocyte cell extracts, suggesting that the domains responsible for the binding of protein I/IIf to monocytes were the A and the extended V regions. Sodium metaperiodate pretreatment of THP-1 cell extracts, tunicamycin pretreatment of monocyte cells or competition with N-acetyl neuraminic acid (NANA) and fucose resulted in a 45-70% reduction in binding activity of the derivatives carrying the extended V region, demonstrating the lectin-like mode of recognition of the monocytic receptor by the extended V region and the role of NANA and fucose in this recognition process. Besides, the stimulation of monocytes to release TNF-alpha by the derivatives containing the A region and the extended V region was effective and was not affected by the addition of polymyxin B or vitamin D3, suggesting that CD14 does not play the role of receptor in stimulation of monocytes by protein I/IIf to release TNF-alpha.

Influence of protective isolation on outcome of allogeneic bone marrow transplantation for leukemia

Various isolation strategies are used to prevent infections during bone marrow transplantation; data on their efficacy are lacking. We studied whether use of high efficiency particulate air filtration (HEPA) and/or laminar airflow (LAF) units affect transplant-related mortality (TRM) or survival in the first year after allogeneic transplantation. 5065 patients with leukemia receiving bone marrow transplants from an HLA identical sibling (n = 3982) or alternative related or unrelated donors (n = 1083) between 1988 and 1992 were reported to the International Bone Marrow Transplant Registry by 222 teams. Two types of isolation were considered: (1) conventional protective isolation with single patient room and any combination of hand-washing, gloves, mask and gown; and (2) HEPA and/or LAF. Cox proportional hazards regression models were used to determine the relative risks (RRs) of transplant-related mortality (TRM) and of deaths from any cause in patients treated in HEPA/LAF units compared to patients treated in conventional isolation. HLA-identical sibling and alternative donor transplants were analyzed separately. Risks of TRM and overall mortality in the first 100 days post-transplant were significantly lower among patients treated in HEPA/LAF units than in those treated conventionally. RRs of TRM were 0.76 (P = 0.009) for recipients of HLA-identical sibling transplants and 0.65 (P = 0.003) for recipients of alternative donor transplants. Correspondingly RRs of overall mortality were 0.80 (P = 0.02) and 0.65 (P = 0.0006). Decreased risks of TRM and of death in the first 100 days post-transplant resulted in significantly higher 1-year survival rates in patients treated in HEPA/LAF rather than in conventional isolation units. Use of HEPA and/or LAF to prevent infections decreases TRM and increases survival after allogeneic bone marrow transplants for leukemia.

Desferrioxamine enhances the effects of gamma radiation on clonogenic survival and the formation of chromosomal aberrations in endothelial cells

Vascular injury and endothelial damage contribute to the efficacy and complications of radiotherapy. Iron chelation protects against iron-catalyzed oxidative injury, but it also inhibits DNA synthesis in proliferating cells and can cause apoptosis. We examined the prevailing effects of iron chelation on the survival of gamma-irradiated human umbilical vein endothelial cells by treating monolayers, primarily in the G1/G0 phase of the cell cycle, with the iron chelator desferrioxamine for 24 h prior to gamma irradiation. Desferrioxamine treatment alone diminished plating efficiency by inducing apoptosis and delaying proliferation; this effect disappeared by 48 h. Desferrioxamine treatment reduced clonogenic survival after exposure to 2.5 Gy gamma radiation, but neither iron loading with hemin nor treatment with another iron chelator, 2,2-dipyridyl, which is a potent inhibitor of ribonucleotide reductase, had an effect on survival after irradiation. Clonogenic survival and chromosomal aberrations were measured in parallel in endothelial cells treated with desferrioxamine after increasing doses of gamma radiation. In a linear-quadratic model of survival, desferrioxamine treatment did not change the occurrence of directly lethal lesions, but it significantly increased sublethal injury. Desferrioxamine was not clastogenic alone, but it increased the frequency of formation of chromosomal rings and of excess acentric fragments after gamma irradiation.

Economic analyses of bone marrow and blood stem cell transplantation for leukemias and lymphoma: what do we know?

The use of blood and/or bone marrow stem cell transplantation (SCT) grew extensively in the last decade as technological advances led to improved outcomes and wider availability. The first study of SCT costs, however, was not published until 1989. This paper summarizes current knowledge about costs and cost-effectiveness of allogeneic and autologous SCT for leukemias and lymphoma. Methodological issues in cost studies such as types of costs, methods of data collection, and time horizons are discussed, and studies are evaluated with regard to these issues. Considerations specific to economic analyses of SCT are considered, including the potential impact of technological changes, learning curve effects, and inter-institutional differences.

Survival with bone marrow transplantation versus hydroxyurea or interferon for chronic myelogenous leukemia. The German CML Study Group

Hydroxyurea, interferon, and HLA-identical sibling bone marrow transplantation are common therapies for chronic myelogenous leukemia (CML) in chronic phase. Which is best is controversial. The purpose of this study was to compare survival of patients with CML receiving HLA-identical sibling transplants versus hydroxyurea or interferon. The transplant cohort included 548 recipients of HLA-identical sibling transplants, reported to the International Bone Marrow Transplant Registry. The nontransplant cohort included 196 patients receiving hydroxyurea (n = 121) or interferon (n = 75) on a randomized trial of the German CML Study Group. Survivals were compared using proportional hazards regression with fixed and time-dependent variables to adjust for patient differences and changing risks over time. For the first 18 months after diagnosis, mortality was higher in the transplant than the nontransplant cohort (relative risk [RR], 5.85; P < .0001). From 18 to 56 months, mortality was similar (RR, 0.80; P = .38). After 56 months, mortality was lower in the transplant cohort (RR, 0.16; P < .0001). Seven-year survival probabilities (95% confidence interval) were 58% (50% to 66%) with transplant and 32% (22% to 41%) with hydroxyurea or interferon. There was a significant survival advantage for hydroxyurea or interferon in the first 4 years after diagnosis and for transplants starting 5.5 years after diagnosis. For transplants done within 1 year of diagnosis, the survival advantage for transplantation began earlier. Survival advantage for transplants was greater and occurred earlier in patients with intermediate- and high-risk prognostic features than in those with low-risk features. This study confirms higher early mortality, but a long-term survival advantage for HLA-identical sibling transplants over hydroxyurea or interferon in CML.

Graft-versus-leukemia effects in T lineage and B lineage acute lymphoblastic leukemia

T and B lineage ALL cells express different levels of HLA-class II antigens, which may serve as targets for graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL). The object of this study was to determine whether GVL effects after HLA-identical sibling bone marrow transplantation differed in T and B lineage ALL. We studied 1132 patients with ALL of T lineage (n = 416) or of B lineage (cALLa+) (n = 716) transplanted in first (n = 605) or second (n = 527) remission with bone marrow from an HLA-identical sibling donor, between 1982 and 1992, and reported to the IBMTR by 165 teams. Cox proportional hazards regression models were used to determine the relative risk (RR) of relapse in patients with acute (grades II-IV) or chronic GVHD vs patients without GVHD. Acute and chronic GVHD were considered as time-dependent covariates. Patients transplanted in first and second remission were analyzed separately. GVHD decreased relapse risks to a similar extent in T and B lineage ALL. For first remission transplants, relative risks of relapse for patients with vs those without GVHD was 0.34 for T lineage ALL and 0.44 for B lineage ALL. Corresponding relative risks in second remission transplants were 0.54 and 0.61. This study confirms earlier findings of an antileukemia effect of GVHD in ALL. This effect was similar in T lineage and B lineage ALL, despite probable differences in HLA-class II antigen expression.

Infant tuberculosis in Austria--trend reversal since 1990?

Since 1990 a relatively high number of cases of childhood tuberculosis has been observed in Austria, mainly occurring in the age-group of 0-4 years. Within this group most cases were registered in 1995. Since the beginning of 1995 the establishment of a lab-supported nationwide data collection system enables a more detailed recording of the cases diagnosed. Out of the 85 cases with infant tuberculosis registered in 1995 and 1996, 66 were diagnosed with pulmonary manifestation. In 45 cases tuberculosis was proven by culture. In nine (20%) of these cases the most likely route of infection has appeared to be direct transmission from an adult in the same household suffering from culture proven tuberculosis in the same year. For three of the cases the DNA of the isolated Mycobacterium tuberculosis strains from the adult and the infant was typed using RFLP analysis. In each case identical strains could be demonstrated.

Complete bipartition of the atlas in the Klippel-Feil syndrome. A radiologically illustrated case report

A patient with the Klippel-Feil syndrome is described who presented with pain in the neck after a trauma. No fractures were found. Instead, a midline cleft in both the anterior and posterior atlantic arches was found which represents an extremely rare congenital anomaly.

Estimation of variance in Cox's regression model with shared gamma frailties

The Cox regression model with a shared frailty factor allows for unobserved heterogeneity or for statistical dependence between the observed survival times. Estimation in this model when the frailties are assumed to follow a gamma distribution is reviewed, and we address the problem of obtaining variance estimates for regression coefficients, frailty parameter, and cumulative baseline hazards using the observed nonparametric information matrix. A number of examples are given comparing this approach with fully parametric inference in models with piecewise constant baseline hazards.

Immune response in a murine model of congenital toxoplasmosis: increased susceptibility of pregnant mice and transplacental passage of Toxoplasma gondii are type 2-dependent

We used a model of acquired toxoplasmosis to study the immune response in pregnant BALB/c mice (IL-4+/+) and in pregnant transgenic IL-4-deficient BALB/c mice (IL-4-/-) during acute toxoplasmosis. Female BALB/c mice were infected orally by 20 tissue cysts of the avirulent PRU strain of Toxoplasma gondii on day 11 of pregnancy. Splenocyte cultures were used to explore proliferative responses and cytokine production in vitro. Parasite loads were determined in the lungs on day 7 post-infection and in the brain on day 30 post-infection. After infection, cultured spleen cells from pregnant mice produced more IFN-gamma (a Type I cytokine) and more NO than non pregnant mice, and the Type 2 response (IL-4 and IL-10) was weak. Although this kind of immune response may be required for mice to recover from toxoplasmosis, pregnant mice were more susceptible to infection than non pregnant mice, as illustrated by a larger parasite load in lungs and brain. Pregnant IL-4-/- mice showed lower susceptibility to T. gondii infection and a lower materno-fetal transmission rate (24% vs. 53% infected fetuses) without increased production of Type I cytokines (IFN-gamma and NO). These data indicate that Type 2 response plays an important role in increasing mouse susceptibility to T. gondii infection during pregnancy and that IL-4 and pregnancy-associated substances increase the transplacental passage of T. gondii.

Survival of patients with chronic myelogenous leukaemia relapsing after bone marrow transplantation: comparison with patients receiving conventional chemotherapy

Treatment with busulphan and/or hydroxyurea rarely produces remission in patients with chronic myelogenous leukaemia (CML) in chronic phase. HLA-identical sibling transplants almost always produce remission, and only about 20% of patients relapse post-transplant. The increased anti-leukaemic efficacy of transplants results from intensive pretransplant treatment and immune-mediated anti-leukaemia effects. We studied 433 patients surviving > or = 2 years after diagnosis of CML to determine if patients who have relapsed after a transplant in chronic phase have longer survival from diagnosis than comparable subjects receiving chemotherapy. The chemotherapy cohort included 344 adults < 50 years of age treated on consecutive trials of the Italian Cooperative Study Group on CML between 1973 and 1986. The transplant cohort included 89 patients reported to the International Bone Marrow Transplant Registry who relapsed after an HLA-identical sibling bone marrow transplant carried out between 1978 and 1992. Survivals in the two groups were compared using Cox proportional hazards regression to adjust for prognostic variables. Median survival was 65 months in the chemotherapy cohort and 86 months in the transplant cohort. The 7-year probability (95% confidence interval) of survival was 34% (28-39%) in the chemotherapy cohort and 57% (43-70%) in the transplant cohort (P=0003). There was no difference in survival of patients relapsing after T-cell depleted and non-T-cell-depleted transplants. We conclude that patients who relapse after an HLA-identical sibling bone marrow transplant for CML in chronic phase have longer survival from diagnosis than comparable patients receiving chemotherapy. This effect is most likely to be the result of intensive chemotherapy and/or radiation given for pretransplant conditioning.

The N-terminal half part of the oral streptococcal antigen I/IIf contains two distinct binding domains

In order to investigate the binding properties of the antigen I/IIf from Streptococcus mutans, we analyzed the binding activity of five I/IIf derivatives expressed by I/IIf gene derivatives obtained by insertion of a kanamycin resistance marker. ELISA-derived binding assays showed that the derivatives containing both the N-terminal alanine-rich domain (A-region) and an A-region distal domain extending to amino-acid 766 were the most effective in binding biotinylated (Biot-) human salivary components (SAC) and Biot-epithelial cell membrane components. Sodium metaperiodate treatment of SAC inhibited these interactions, suggesting a binding specificity of the A-region distal domain for carbohydrate residues. All the I/IIf derivatives were found to bind Biot-type I collagen, Biot-laminin, Biot-keratin, and Biot-fibronectin, the derivatives containing the A-region but lacking the A-region distal domain exhibiting the highest binding levels. Sodium metaperiodate treatment of laminin had no effect on its binding to the derivatives, suggesting that carbohydrate residues of the ligand were not involved.

Detection of BCR/ABL RNA transcripts using the polymerase chain reaction is highly predictive for relapse in patients transplanted with unrelated marrow grafts for chronic myelogenous leukaemia

Relapse after allogeneic bone marrow transplantation (BMT) for chronic myelogenous leukaemia (CML) is thought to result from residual leukaemia cells which survive the intensive conditioning regimen and are not eradicated by donor-derived immune effector cells capable of mediating a graft-versus-leukaemia (GVL) effect. Early relapse can be detected using highly sensitive assays such as the polymerase chain reaction (PCR) which have been shown to have predictive value for subsequent relapse in selected patient populations. The validity of PCR for predicting CML relapse in unrelated marrow transplant recipients where the GVL effect appears to be augmented due to increased HLA disparity between donor and recipient, however, has not been well defined. In this study we assessed the prognostic value of PCR in a cohort of 52 patients transplanted with T-cell-depleted unrelated marrow grafts for CML. The actual probability of relapse at 3 years was 71% in patients with at least one positive assay versus 6% in patients with no positive assays post-transplant. Patients with one or more positive assays at any time post-transplant had a 56-fold increased risk of relapse which was significantly higher (P=0.0002) than that observed in patients who remained persistently PCR negative. Moreover, PCR detected relapse a median of 5 months earlier than cytogenetic analysis in a subgroup of patients in whom concurrent sampling had been performed. These data validate the use of PCR as a prognostic test in this patient population and may help to identify a cohort of patients to be considered as candidates for pre-emptive adoptive immunotherapy.

Bone marrow transplantation for severe aplastic anemia: has outcome improved?

Bone marrow transplants for severe aplastic anemia were first performed in the 1970s. Transplant regimens, supportive care, and patient selection have changed substantially since then. Our objective was to determine the impact of these changes on transplant outcome. We studied 1,305 recipients of HLA-identical sibling transplants for aplastic anemia between 1976 and 1992, reported to the IBMTR by 179 centers. We compared survival of transplants performed in three intervals (1976 through 1980 [n = 186], 1981 through 1987 [n = 648], and 1988 through 1992 [n = 471]) using Cox proportional hazards regression. Five-year survival (+/-95% confidence interval) increased from 48% +/- 7% in the 1976-1980 cohort to 66% +/- 6% in the 1988-1992 cohort (P < .0001). Risks of graft-versus-host disease (GVHD) and interstitial pneumonia decreased over time, but the risk of graft failure did not. Higher long-term survival resulted primarily from decreased mortality in the first 3 months posttransplantation. Late mortality risks were low and changed little over the intervals studied. In multivariate analysis, changes in transplantation strategies accounted for most but not all of the improved outcome. Use of cyclosporine to prevent GVHD was the most important factor. Changes in patient selection did not seem to explain improved survival. Survival after HLA-identical sibling bone marrow transplantations for aplastic anemia has improved since 1976. Changes in GVHD prophylaxis account for much of this improvement. Other changes may also operate.

Wisconsin healthcare ethics committees

Over the past two decades ethics committees have proliferated in healthcare institutions across the country. Catalysts for this growth include the endorsement of ethics committees by the New Jersey Supreme Court in the Quinlan case, by the President's Commission for the Study of Ethical Problems in Medicine and Biomedical Research (“President's Commission”) in its report entitled Deciding to Forgo Life Sustaining Medical Treatment, by the U.S. Department of Health and Human Services in its 1985 “Baby Doe” regulations, by numerous other courts in treatment decisionmaking opinions issued after Quinlan, and more recently by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO).

Induction of nitric oxide production by polyosides from the cell walls of Streptococcus mutans OMZ 175, a gram-positive bacterium, in the rat aorta

The cardiovascular dysfunctions associated with septic shock induced by gram-negative or gram-positive bacteria (gram-positive or gram-negative septic shock) are comparable. In gram-negative septic shock, lipopolysaccharide (LPS) induces nitric oxide (NO) synthase, which contributes to the vascular hypotension and hyporeactivity to vasoconstrictors. The role of NO in gram-positive septic shock and the nature of the bacterial wall components responsible for the vascular effects of gram-positive bacteria are not well known. This study investigated the vascular effects of cell wall serotype polyosides, rhamnose glucose polymers (RGPs), from Streptococcus mutans, in comparison with lipoteichoic acid (LTA) from Staphylococcus aureus, on the induction of NO synthase activity in the rat aorta. We show that 10 microg of both RGPs and LTA per ml induced hyporeactivity to noradrenaline, L-arginine-induced relaxation, increases of 2.2- and 7.8-fold, respectively, of cyclic GMP production, and increases of 7- and 12-fold in nitrite release. All of these effects appeared after several hours of incubation and were inhibited by N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase. Electron paramagnetic resonance spin trapping experiments demonstrated directly that RGPs and LTA induced NO overproduction (four- to eightfold, respectively) in rat aortic rings; this production was inhibited by L-NAME and prevented by dexamethasone. These results demonstrate directly the induction of NO production in vascular tissue by LTA and show that another, chemically different component of gram-positive bacteria can also have these properties. This result suggests that different components of the gram-positive bacterial wall could be implicated in the genesis of cardiovascular dysfunctions observed in gram-positive septic shock.

IBMTR Severity Index for grading acute graft-versus-host disease: retrospective comparison with Glucksberg grade

Acute graft-versus-host disease (GVHD) severity is graded by pattern of organ involvement and clinical performance status using a system introduced by Glucksberg and colleagues 21 years ago. We examined how well Glucksberg grade predicted transplant outcome and constructed a Severity Index not requiring subjective assessment of performance in 2881 adults receiving an HLA-identical sibling T-cell-depleted (n = 752) or non-T-cell-depleted (n = 2129) bone marrow transplant for leukaemia between 1986 and 1992. Relative risks (RR) of relapse, treatment-related mortality (TRM) and treatment failure (TF) (relapse or death) were calculated for patients with (Glucksberg Grade I, II or III/IV acute (GVHD) versus those without acute GVHD and for patients with distinct patterns of organ involvement regardless of Glucksberg grade. Using data for non-T-cell-depleted transplants, a Severity Index was developed grouping patients with patterns of organ involvement associated with similar risks of TRM and TF. Higher Glucksberg grade predicted poorer outcome; however, patients with the same grade but different patterns of skin, liver or gut involvement often had significantly different outcomes. The revised Severity Index groups patients in four categories, A-D. Compared to patients without acute GVHD, RRs (95% confidence interval) of TF were 0.85 (0.69, 1.05) for patients with Index A, 1.21 (1.02, 1.43) with B, 2.19 (1.78, 2.71) with C, and 5.69 (4.57, 7.08) with D. Prognostic utility of the Index was tested in patients receiving T-cell-depleted transplants; similar RRs of TF were observed. An acute GVHD Severity Index is proposed to enhance design and interpretation of clinical trials in the current era of allogeneic blood and bone marrow transplantation.

High-dose chemotherapy with autologous hematopoietic stem-cell support for breast cancer in North America

PURPOSE

To identify trends in high-dose therapy with autologous hematopoietic stem-cell support (autotransplants) for breast cancer (1989 to 1995).

PATIENTS AND METHODS

Analysis of patients who received autotransplants and were reported to the Autologous Blood and Marrow Transplant Registry. Between January 1, 1989 and June 30, 1995, 19,291 autotransplants were reviewed; 5,886 were for breast cancer. Main outcomes were progression-free survival (PFS) and survival.

RESULTS

Between 1989 and 1995, autotransplants for breast cancer increased sixfold. After 1992, breast cancer was the most common indication for autotransplant. Significant trends included increasing use for locally advanced rather than metastatic disease (P < .00001) and use of blood-derived rather than marrow-derived stem cells (P < .00001). One-hundred-day mortality decreased from 22% to 5% (P < .0001). Three-year PFS probabilities were 65% (95% confidence intervals [Cls], 59 to 71) for stage 2 disease, and 60% (95% Cl, 53 to 67) for stage 3 disease. In metastatic breast cancer, 3-year probabilities of PFS were 7% (95% Cl, 4 to 10) for women with no response to conventional dose chemotherapy; 13% (95% Cl, 9 to 17) for those with partial response; and 32% (95% Cl, 27 to 37) for those with complete response. Eleven percent of women with stage 2/3 disease and less than 1% of those with stage 4 disease participated in national cooperative group randomized trials.

CONCLUSION

Autotransplants increasingly are used to treat breast cancer. One-hundred-day mortality has decreased substantially. Three-year survival is better in women with earlier stage disease and in those who respond to pretransplant chemotherapy.

Results of allogeneic bone marrow transplants for leukemia using donors other than HLA-identical siblings

PURPOSE

To compare outcomes of bone marrow transplants for leukemia from HLA-identical siblings, haploidentical HLA-mismatched relatives, and HLA-matched and mismatched unrelated donors.

PATIENTS

A total of 2,055 recipients of allogeneic bone marrow transplants for chronic myelogenous leukemia (CML), acute myelogenous leukemia (AML), and acute lymphoblastic leukemia (ALL) were entered onto the study. Transplants were performed between 1985 and 1991 and reported to the International Bone Marrow Transplant Registry (IBMTR). Donors were HLA-identical siblings (n = 1,224); haploidentical relatives mismatched for one (n = 238) or two (n = 102) HLA-A, -B, or -DR antigens; or unrelated persons who were HLA-matched (n = 383) or mismatched for one HLA-A, -B, or -DR antigen (n = 108). HLA typing was performed using serologic techniques.

RESULTS

Transplant-related mortality was significantly higher after alternative donor transplants than after HLA-identical sibling transplants. Among patients with early leukemia (CML in chronic phase or acute leukemia in first remission), 3-year transplant-related mortality (+/-SE) was 21% +/- 2% after HLA-identical sibling transplants and greater than 50% after all types of alternative donor transplants studied. Among patients with early leukemia, relative risks of treatment failure (inverse of leukemia-free survival), using HLA-identical sibling transplants as the reference group, were 2.43 (P < .0001) with 1-HLA-antigen-mismatched related donors, 3.79 (P < .0001) with 2-HLA-antigen-mismatched related donors, 2.11 (P < .0001) with HLA-matched unrelated donors, and 3.33 (P < .0001) with 1-HLA-antigen-mismatched unrelated donors. For patients with more advanced leukemia, differences in treatment failure were less striking: 1-HLA-antigen-mismatched relatives, 1.22 (P = not significant [NS]); 2-HLA-antigen-mismatched relatives, 1.81 (P < .0001); HLA-matched unrelated donors, 1.39 (P = .002); and 1-HLA-antigen-mismatched unrelated donors, 1.63 (P = .002).

CONCLUSION

Although transplants from alternative donors are effective in some patients with leukemia, treatment failure is higher than after HLA-identical sibling transplants. Outcome depends on leukemia state, donor-recipient relationship, and degree of HLA matching. In early leukemia, alternative donor transplants have a more than twofold increased risk of treatment failure compared with HLA-identical sibling transplants. This difference is less in advanced leukemia.

Results of transplanting bone marrow from genetically identical twins into patients with aplastic anemia

BACKGROUND

Aplastic anemia is caused by several diverse factors, including a lack of or defective hematopoietic stem cells, immune abnormalities, and disorders of the bone marrow microenvironment. The outcome of transplanting bone marrow from genetically identical twins into patients with aplastic anemia may help define how frequently these factors play a role in this condition.

OBJECTIVE

To determine the outcome of transplanting bone marrow from genetically identical twins into patients with aplastic anemia.

DESIGN

Observational study.

SETTING

31 centers participating in the international Bone Marrow Transplant Registry.

PATIENTS

40 patients with aplastic anemia who received bone marrow transplants from their genetically identical twins between 1964 and 1992.

INTERVENTION

23 patients received their first bone marrow transplant without pretransplantation conditioning; 17 received it after pretransplantation conditioning with cyclophosphamide alone or combined with other drugs or radiation. Six patients received post-transplantation immunosuppressive therapy with methotrexate, cyclosporine, and corticosteroids, alone or in combination.

MEASUREMENTS

Outcomes of transplantation, including hematologic recovery and survival.

RESULTS

Seven of 23 patients who received their first transplant without receiving conditioning had sustained complete hematologic recovery. One of 16 patients who did not have complete recovery after the first transplantation recovered after a second transplantation, which was not preceded by conditioning. The other 15 patients had two to five transplantations that were preceded by conditioning; in 13 patients, sustained bone marrow function was recovered. Twelve of 17 patients whose first transplantation was preceded by conditioning had sustained complete hematologic recovery. The likelihood of hematologic recovery was greater in patients who had conditioning before the first transplantation (P = 0.033). The actuarial 10-year survival rate for the 40 patients was 78% (95% CI, 59% to 92%). The survival rate was higher in patients who did not have conditioning before the first transplantation (patients without conditioning, 87% [range, 65% to 99%]; patients with conditioning, 70% [range, 47% to 89%]; P = 0.037).

CONCLUSIONS

Most patients with aplastic anemia recover bone marrow function after receiving a transplant from a genetically identical twin. Pretransplantation conditioning may increase the chance of bone marrow recovery but does not seem to improve survival.

The role of frailty models and accelerated failure time models in describing heterogeneity due to omitted covariates

In survival analysis, deviations from proportional hazards may sometimes be explained by unaccounted random heterogeneity, or frailty. This paper recalls the literature on omitted covariates in survival analysis and shows in a case study how unstably frailty models might behave when asked to account for unobserved heterogeneity in standard survival analysis with no replications per heterogeneity unit. Accelerated failure time modelling seems to avoid these difficulties and also to yield easily interpretable results. We propose that it would be advantageous to upgrade the accelerated failure time approach alongside the hazard modelling approach to survival analysis.