Alemtuzumab as graft-versus-host disease (GVHD) prophylaxis strategy in a developing country: lower rate of acute GVHD, increased risk of cytomegalovirus reactivation

Acute graft-versus-host disease (aGVHD) and cytomegalovirus reactivation are important complications after allogeneic stem cell transplantation (alloHSCT). Here, we evaluated the impact of treatment with alemtuzumab on the occurrence of aGVHD, cytomegalovirus reactivation and survival after alloHSCT. This was a prospective cohort study conducted at the allo-HSCT unit of Hospital das Clínicas, Universidade Federal de Minas Gerais, Brazil, from January 2009 to December 2011. Fifty-seven patients who underwent alloHSCT were included. Forty-five (79%) patients had a malignant disease. Alemtuzumab was administered before the conditioning regimen at a dose of 1 mg/kg in children and 30 mg/day for 2 days in adults or children weighing more than 40 kg (a total dose of 60 mg) with a non-malignant disease or patients with a malignant disease and high-risk for GVHD mortality. Alemtuzumab was used in 23 (40%) patients, of whom 17 received a reduced-intensity conditioning. Eleven patients presented aGVHD (grade 2–4) and only 1 of them received alemtuzumab. Cumulative incidence of aGVHD (grade 2–4) at day 100 after transplantation (D+100) was 4 for patients receiving alemtuzumab and 29% for patients not receiving alemtuzumab. Cumulative incidence of cytomegalovirus reactivation for patients receiving or not alemtuzumab was 62 and 38%, respectively. Sixteen patients died in the first 100 days after alloHSCT, most of them due to bacterial sepsis. Only 2 patients died of aGVHD until D+100. Overall survival was 50% without any impact of alemtuzumab. Alemtuzumab effectively controlled aGVHD but increased the risk of cytomegalovirus reactivation without improving survival.

Influence of glutathione S-transferase gene polymorphisms on busulfan pharmacokinetics and outcome of hematopoietic stem-cell transplantation in thalassemia pediatric patients

Hematopoietic stem-cell transplantation (HSCT) is currently the only curative therapeutic option for the treatment of thalassemia. In spite of the high cure rate, HSCT can lead to life-threatening adverse events in some patients. Busulfan (Bu) is a key component of the conditioning regimen prior to HSCT. Inter-individual differences in Bu pharmacokinetics (PK) are hypothesized to influence Bu efficacy and toxicity. Since Bu is mainly metabolized by glutathione S-transferase (GST), we investigated the relationship of GSTA1 and GSTM1 genotypes with first-dose PK and HSCT outcomes in 44 children with thalassemia intermedia and thalassemia major. All children received a myeloablative conditioning regimen with IV Bu. Association analysis revealed a relationship between GSTA169C>T (or haplotype *A/*B) and first Bu dose PK that was dependent on sex and Pesaro risk classification (PRC). Among female patients and patients with PRC I-II, homozygous individuals for the GSTA1T-69 allele defining haplotype *B, had higher Bu exposure and lower clearance (P⩽0.01). Association with HSCT outcomes showed that patients with the GSTM1 null genotypes had higher occurrence of regimen-related toxicity (P=0.01). These results suggest that GST genotypes could be useful to tailor the first Bu dose accordingly to improve HSCT outcome.

The association of cytochrome P450 genetic polymorphisms with sulfolane formation and the efficacy of a busulfan-based conditioning regimen in pediatric patients undergoing hematopoietic stem cell transplantation

Cytochrome P450 enzymes (CYPs) and flavin-containing monooxygenases (FMOs) likely have a role in the oxidation of intermediate metabolites of busulfan (Bu). In vitro studies to investigate the involvement of these enzymes are cumbersome because of the volatile nature of the intermediate metabolite tetrahydrothiophene (THT) and the lack of sensitive quantitation methods. This study explored the association between the CYP2C9, CYP2C19, CYP2B6 and FMO3 genotypes and sulfolane (Su, a water soluble metabolite of Bu) plasma levels in children undergoing hematopoietic stem cell transplantation (HSCT). The relationship between these genotypes and the effectiveness of myeloablative conditioning was also analyzed. Sixty-six children receiving an intravenous Bu-based myeloablative conditioning regimen were genotyped for common functional variant alleles in CYP2C9 (*2 and *3), CYP2C19 (*2 and *17), FMO3 (rs2266780, rs2266782 and rs1736557) and CYP2B6 (*5 and *9). The plasma levels of Bu and its metabolite Su were measured after the ninth Bu dose in a subset of 44 patients for whom plasma samples were available. The ratio of Bu to Su was considered the metabolic ratio (MR) and was compared across the genotype groups. Higher MRs were observed in CYP2C9*2 and *3 allele carriers (mean±s.d.: 7.8±3.6 in carriers vs 4.4±2.2 in non-carriers; P=0.003). An increased incidence of graft failure was observed among patients with an MR>5 compared with those with MR values <5 (20% vs 0%; P=0.02). In contrast, a significantly higher incidence of relapse and graft failure (evaluated as event-free survival) was observed in patients with malignant disease who carried CYP2B6 alleles with reduced function on both chromosomes compared with carriers of at least one normal allele (100% vs 40%; P=0.0001). These results suggest that CYP2C9 has a role in the oxidation reactions of THT and indicate that it may be possible to predict the efficacy of Bu-based myeloablative conditioning before HSCT on the basis of CYP genotypes and Bu MRs.

Comparison of outcomes after single or double cord blood transplantation in adults with acute leukemia using different types of myeloablative conditioning regimen, a retrospective study on behalf of Eurocord and the Acute Leukemia Working Party of EBMT

We report outcomes after single (s) and double (d) umbilical cord blood transplantation (UCBT) after myeloablative conditioning (MAC) regimen for 239 patients transplanted for acute leukemia in first complete remission (CR1). All sUCBT patients received a total nucleated cell dose >2.5 × 10(7)/kg. Conditioning regimen for sUCBT was total body irradiation (TBI)12 Gy- or busulfan (BU)-based ± fludarabine (Flu) (n=68, group 1), thiotepa+BU+Flu (TBF) (n=88, group 2), and for dUCBT it was TBI12 Gy+cyclophosphamide ± Flu (n=83, group 3). dUCBT recipients were younger, received higher cell dose and less frequently antithymocyte globulin. In multivariate analysis, we found similar neutrophil recovery among the three groups; however, acute graft-versus-host disease II-IV was higher in dUCBT compared with others. Non-relapse mortality and relapse incidence were not statistically different among the three groups. Leukemia-free survival was 30% for sUCBT using TBI- or BU-based MAC compared with 48% for sUCBT TBF and 48% for dUCBT (P=0.02 and P=0.03, respectively), and it was not statistically different between sUCBT with TBF and dUCBT. In conclusion, use of sUCBT with adequate cell dose (>2.5 × 10(7)/kg) and a specific conditioning regimen in the MAC setting results in similar outcomes as dUCBT. The choice of TBF conditioning regimen for sUCBT may improve results, and whether this regimen may be effective in dUCBT should be further analyzed.

Use of inflammatory molecules to predict the occurrence of fever in onco-hematological patients with neutropenia

Febrile neutropenia remains a frequent complication in onco-hematological patients, and changes in the circulating level of inflammatory molecules (IM) may precede the occurrence of fever. The present observational prospective study was carried out to evaluate the behavior of plasma tumor necrosis factor alpha (TNF-α), soluble TNF-α I and II receptors (sTNFRI and sTNFRII), monocyte chemoattractant protein-1 [MCP-1 or chemokine (c-c motif) ligand 2 (CCL2)], macrophage inflammatory protein-1α (MIP-1α or CCL3), eotaxin (CCL11), interleukin-8 (IL-8 or CXCL8), and interferon-inducible protein-10 (IP-10 or CXCL10) in 32 episodes of neutropenia in 26 onco-hematological patients. IM were tested on enrollment and 24-48 h before the onset of fever and within 24 h of the first occurrence of fever. Eight of 32 episodes of neutropenia did not present fever (control group) and the patients underwent IM tests on three different occasions. sTNFRI levels, measured a median of 11 h (1-15) before the onset of fever, were significantly higher in patients presenting fever during follow-up compared to controls (P = 0.02). Similar results were observed for sTNFRI and CCL2 levels (P = 0.04 for both) in non-transplanted patients. A cut-off of 1514 pg/mL for sTNFRI was able to discriminate between neutropenic patients with or without fever during follow-up, with 65% sensitivity, 87% specificity, and 93% positive predictive value. Measurement of the levels of plasma sTNFRI can be used to predict the occurrence of fever in neutropenic patients.

HCMV gB genotype and its association with cytokine levels in hematopoietic stem cell transplantation

BACKGROUND

Glycoprotein B (gB) has been implicated in determining the pathogenicity and clinical outcomes of human cytomegalovirus (HCMV) disease.

OBJECTIVE

The purpose of this study was to assess the prevalence of gB genotypes in allogeneic hematopoietic stem cell transplantation (allo-HSCT) and the relationship between it and cytokine levels in saliva and blood samples. The impact of these parameters on patients' survival was also investigated.

METHODS

Samples were obtained from 63 patients receiving an allo-HSCT. HCMV gB genotyping was carried out by multiplex nested PCR. The cytokine levels were assessed using ELISA assay.

RESULTS

A single or mixed genotype infection was detected in the saliva and blood of 36/63 and 52/63 subjects, respectively. Patients with gB2 in their saliva showed lower IL-10 levels in comparison with patients without gB2. Reduced blood levels of IFN-γ and IL-1β were also found in recipients with the HCMV gB4 genotype compared with patients without it. Decreased IL-1β and increased IL-10 blood levels were associated with lower survival. However, HCMV gB genotypes have no impact on patient outcome.

CONCLUSION

Decreased IL-1β and increased IL-10 levels in the blood are associated with lower survival. HCMV genotypes are associated with different cytokine levels in saliva and blood.

Saliva as a source of HCMV DNA in allogeneic stem cell transplantation patients

OBJECTIVE

The purpose of this study was to investigate the use of saliva for the identification of human cytomegalovirus (HCMV) in allogeneic hematopoietic stem cell transplant patients by real time PCR compared with blood.

MATERIALS AND METHODS

Saliva and blood samples were sampled weekly in 30 allogeneic hematopoietic stem cell transplant patients until 100 days after transplant. Total genomic DNA, extracted from saliva and whole-blood samples, was used for HCMV real time PCR. Nonparametric tests were performed, and P value <or=0.05 was considered statistically significant.

RESULTS

Human cytomegalovirus DNA load in saliva showed a high correlation with viral DNA in the blood (R = 0.858; P < 0.0001). Blood DNA levels also correlated with HCMV antigenemia (R = 0.773; P < 0.0001). The HCMV levels in saliva (P = 0.015) and blood (P = 0.008) showed higher levels at the beginning of antiviral treatment, with clear reduction after this period. Saliva showed earlier HCMV reactivation than blood detected by real time PCR and antigenemia assay in 11 out of 22 subjects.

CONCLUSIONS

This study shows that the real time PCR test could be useful to identify HCMV DNA in saliva and to monitor patients at risk of cytomegalovirus disease after allogeneic hematopoietic stem cell transplant. However, further studies are necessary to confirm this data.

Cytomegalovirus shedding in the oral cavity of allogeneic haematopoietic stem cell transplant patients

OBJECTIVE

This study was designed to investigate the effect of allogeneic haematopoietic stem cell transplantation (HSCT) on cytomegalovirus (CMV) shedding in the saliva by nested polymerase chain reaction (nested PCR) and its impact on patient survival.

PATIENTS AND METHODS

One hundred and twenty-four HSCT patients and 124 healthy volunteers were included in the study. Oral swabs were taken before, after 100 days and 1 year of HSCT at the buccal mucosa. Nested PCR was used to detect CMV in the saliva. Time of death after HSCT was displayed, by means of the Kaplan-Meier method, for the following parameters: age and gender of the patient, donor gender, primary disease, stem cell source, platelet number, chronic graft vs host disease (cGVHD) of salivary glands and oral mucosa, and oral CMV shedding. Cox proportional hazards model was used for multivariate survival analysis.

RESULTS

While none of the individuals in the control group showed positive swabs for CMV, the frequency of positive CMV oral swabs in patients at day + 100 after HSCT (45.2%) was statistically higher than before (7.2%) and 1 year after HSCT (17.5%). The presence of CMV was not associated with cGVHD and did not have any impact on post-transplant survival.

CONCLUSIONS

The present study shows that oral CMV shedding occurs after HSCT, especially at day +100 post-transplant. Identification of CMV in the saliva might be important for the early diagnosis of CMV infection in allo-HSTC.

Granulocyte colony-stimulating factor for poor graft function after allogeneic stem cell transplantation: 3 days of G-CSF identifies long-term responders

Poor graft function (PGF) is a frequent cause of morbidity after allogeneic hematopoietic stem cell transplantation (allo-HSCT). To study the value of granulocyte colony-stimulating factor (G-CSF) in PGF, we retrospectively analyzed 81 episodes of PGF in 66 patients transplanted from 01/94 to 01/99 from an HLA-identical sibling (n = 45) or an unrelated (n = 21) donor. Median age was 29 years, 55 patients had malignancies. A total of 11 patients received a CD34+ selected graft. Viral infections (25%), myelotoxic drug (33%), fungal/bacterial infections (14%), and GVHD (31%) were present before PGF diagnosis. Median time from allo-HSCT to PGF was 75 (25-474) days. All patients were treated with G-CSF. In 77/81 episodes, there was a response that was sustained in 57. A total of 27 patients presented an increase of white cell count (WBC) >0.1 x 10(9)/l after 3 days of G-CSF. The 5-year survival was 37% and was significantly better in patients with increased WBC > 0.1 x 10(9)/l after 3 days of G-CSF (65 vs 18%, P < 0.0001). In multivariate analysis, increased WBC > 0.1 x 10(9)/l after 3 days of G-CSF (P = 0.002) was associated with better survival, while BuCy-based conditioning (P = 0.02) and GVHD (P = 0.005) were associated with higher risk of death. In conclusion, hematological response after 3 days with G-CSF predicted a better survival for patients with PGF after allo-SCT.

Differential vulnerability of the rat retina, suprachiasmatic nucleus and intergeniculate leaflet to malnutrition induced during brain development

We investigated in young rats the effects of malnutrition on the main structures of the circadian timing system: retina, hypothalamic suprachiasmatic nuclei (SCN), thalamic intergeniculate leaflet, retinohypothalamic- and geniculohypothalamic tracts. Control rats were born from mothers fed a commercial diet since gestation, and malnourished rats from mothers fed a multideficient diet since gestation (GLA group) or lactation (LA group). After weaning, pups received the same diet as their mothers, and were analysed at postnatal days 27, 30-33 and 60-63. Brain sections were processed to visualise in the SCN neuropeptide Y immunoreactivity and terminal labeling after intraocular tracer injections. Nissl staining was used to assess cytoarchitectonic boundaries of the SCN and cell features in retinal whole mounts. Cell counts, morphometric and densitometric analysis were performed. Compared with controls, the total retinal surface was reduced and the topographical distribution of retinal ganglion cells was altered in malnourished rats, with changes in their density. Alterations were also detected in the SCN dimensions in the GLA and LA groups at one and two postnatal months, as well as in the SCN portion occupied by the retinal input in the GLA group at days 30-33, but not in the NPY-containing geniculohypothalamic tract. The present data point to subtle changes, with a low and differential vulnerability to early malnutrition, of structures involved in circadian timing regulation. Furthermore, the present findings suggest that the altered circadian rhythmicity previously documented in malnourished rats cannot be ascribed to impaired development of the retino- and geniculohypothalamic projections to the SCN.

Outcome of treatment in adult acute lymphoblastic leukemia in southern Brazil using a modified german multicenter acute lymphoblastic leukemia protocol

Reports on treatment outcomes in adults with acute lymphoblastic leukemia (ALL) in Brazil are sparse. To evaluate the outcome of patients with ALL managed by the public healthcare system, we studied 42 adults treated from 1990 to 1997 in the Division of Hematology at Hospital de Clínicas, Porto Alegre, Brazil. Of these patients, 14/42 were females and their median age at diagnosis was 26 (17-64) years. The diagnosis of ALL was based on cytological examination of marrow smears, and immunophenotypic and cytogenetic studies, when available. Fifty percent of the patients expressed CD10, 30% were CD10 negative and CD19 positive and 20% expressed T markers. Philadelphia chromosome was found in 4 (7.14%). The chemotherapy protocol was adapted from the German Multicenter ALL (GMALL) 02-84 protocol. The complete remission rate was 93% and the overall survival at 5 years was 41%. No particular risk factor was identified in our series. These results are comparable to the findings of other international studies.

Influence of bone marrow graft lymphocyte subsets on outcome after HLA-identical sibling transplants

OBJECTIVE

The aim of this study was to analyze bone marrow lymphocyte subsets and CD34 cell dose and their influence on the outcomes of bone marrow transplantation.

MATERIALS AND METHODS

Forty-eight patients (median age 30 years, range 5-54) receiving HLA-identical sibling bone marrow transplantation for hematologic malignancies were analyzed.

RESULTS

Median number (range) of nucleated cells and CD34+ cells infused were 2.4 (0.4-6.0) x 10(8)/kg and 3.5 (0.5-13.0) x 10(6)/kg, respectively. Probability of neutrophil recovery was 97%. In a multivariate analysis, time to neutrophil recovery was shortened when a higher number of CD3/CD8 cells was infused (> or =1.0 x 10(7)/kg) (hazard ratio [HR] = 2.13, p = 0.018); when the patient was female or had negative cytomegalovirus serology (HR = 2.03, p = 0.03; HR = 0.41, p = 0.009; respectively). The incidence of grade II to IV acute graft-vs-host disease (GVHD) was 47%. Infusion of >1 x 10(7) CD4 infused/kg increased the risk of acute GVHD (HR = 2.86, p = 0.03). Nineteen of 40 patients at risk experienced chronic GVHD, the risk of which was increased by diagnosis of chronic leukemia (p = 0.03), <2.0 x 10(8) nucleated cells infused/kg (p = 0.05), and a low number of all lymphocyte subsets, except CD19. Estimated 3-year survival rate was 54%. Risk of death was increased in patients receiving <3.5 x 10(6)CD34 infused/kg (HR = 0.37, p = 0.02). Only six patients relapsed.

CONCLUSIONS

A high cell dose of CD3/CD8 is associated with faster neutrophil recovery, whereas a high cell dose of CD4+ cells increases the incidence of acute GVHD. A high number of nucleated cells and CD34+ cells infused was associated with decreased risk of chronic GVHD and improved survival, respectively.

HTLV-1 decreases Th2 type of immune response in patients with strongyloidiasis

Eosinophils, immunoglobulin (Ig)E and cytokines have important roles in defence mechanisms against helminths. In this study, the influence of HTLV-1 infection, characterized by a Th1 type of immune response, was evaluated on the cytokine pattern and parasitic specific IgE response in patients with strongyloidiasis. Patients were divided into four groups: strongyloidiasis without HTLV-1 infection, strongyloidiasis with HTLV-1, HTLV-1 without strongyloidiasis and controls without either helminth infection or HTLV-1. The cytokine profile was determined in supernatants of mononuclear cells stimulated with Strongyloides stercoralis crude antigen and the parasite specific IgE was measured by ELISA. Patients coinfected with HTLV-1 had higher levels of interferon (IFN)-gamma and interleukin (IL)-10 (P < 0.05) and lower levels of IL-5 and IgE (P < 0.05) than patients with strongyloidiasis without HTLV-1. There was an inverse relationship between IFN-gamma and IL-5 (P = 0.01; rs = - 0.37) and between IFN-gamma and parasite specific IgE (P = 0.01; rs = - 0.39), and a direct relationship between IFN-gamma and IL-10 (P = 0.04; rs = 0.35). These data show that coinfection with HTLV-1 decreases IL-5 and IgE responses in patients with strongyloidiasis consistent with a relative switch from Th2 to Th1 response. Immunological responses such as these are important in the control of this helminthic infection.

Comparative study of bacterial infection prevalence between cirrhotic patients with and without upper gastrointestinal bleeding

Bacterial infection is a frequent complication in patients with chronic liver disease, mainly during the advanced stages. There is evidence that the main factors that contribute to a predisposition to infection in cirrhotic patients are related to hepatic failure with consequent immunodeficiency. Invasive procedures (diagnostic or therapeutic) can predispose to bacterial infections, and upper gastrointestinal bleeding (UGB) is considered a potentially important risk factor. A group of cirrhotic patients (child B and C Pugh groups) were evaluated retrospectively by chart reviews regarding the prevalence of bacterial infection during hospitalization to determine whether UGB was a risk factor. An infection was considered present if a specific organ system was identified or if fever (> 38(o)C) persisted for more than 24 hours with associated leukocytosis. Spontaneous bacterial peritonitis was based on classical criteria. Eighty-nine patients were evaluated. Fourty-six patients presented with UGB, and 43 patients had no UGB (control). There were infections recorded in 25/46 (54%) patients with UGB, and 15/43 (35%) in those without UGB (p=0.065). The ratio of the number of infections/admitted patients, was significantly larger in the group with UGB (0.78 +/- 0.89 vs. 0.39 +/- 0.62; p=0.028) since patients had more than one infection. In the UGB group compared to non UGB group, ascites was more frequent (67% vs. 42%; p=0.027); they were more likely to have undergone endoscopic procedures (p<0.001) and the mean +/- SD for platelets count was smaller (96,114 +/- 57,563 vs 145,674 +/- 104,083; p=0.007). The results show that UGB is an important contribution to bacterial infection among Child B and C cirrhotic patients.

Influence of CD34(+) marrow cell dose on outcome of HLA-identical sibling allogeneic bone marrow transplants in patients with chronic myeloid leukaemia

In order to study the influence of bone marrow CD34(+) cell dose on the outcome of allogeneic bone marrow transplantation (BMT), we analysed the results of BMT from HLA-identical siblings donors in 50 patients with chronic myeloid leukaemia (CML). The median numbers of nucleated cells (NC) and CD34(+) cells infused were 2.18 x 10(8)/kg (0.05-4.14 x 10(8)/kg) and 3.12 x 10(6)/kg (0.35-8.52 x 10(6)/kg), respectively. All patients engrafted. In univariate analysis, there was no correlation between the number of CD34(+) cells infused and the time to neutrophil recovery (P = 0.17). The Kaplan-Meier estimate of grade II-IV acute graft-versus-host disease (GVHD) at day 100 was 53 +/- 14% and 2-year survival was 46 +/- 15%. A number of CD34(+) cells infused greater than the median was the main factor increasing survival (P = 0.0006) and decreasing 100 day transplant-related mortality (P = 0.009). Patient-, disease- and transplant-related characteristics were not statistically different among patients receiving more or less than the median number of CD34(+) cells. The rate of infectious deaths was significantly higher in patients receiving less than 3.12 x 10(6) CD34/kg (48% vs 16%, P = 0.01). In a multivariable analysis, two factors associated with increased risk of death were advanced disease status at transplant (HR: 2.5 (95% CI: 1.09-5.75), P = 0.03) and a lower number of marrow CD34(+) cells infused/kg (HR: 4.55 (95% CI: 1.87-10.90), P = 0.0008).

Treatment of T-prolymphocytic leukemia with nonmyeloablative allogeneic stem cell transplantation

AIM

T-prolymphocytic leukemia (T-PLL) is a rare disease of the elderly characterized by a high white blood cell count and organomegaly, and is currently incurable. Our aim was to elicit graft-versus-leukemia reactions in a patient with T-PLL.

METHODS

A 52-yr-old woman with refractory T-PLL underwent a nonmyeloablative regimen followed by allogeneic peripheral blood stem cell transplantation (a "minitransplant") from her HLA-matched sibling.

RESULTS

There was no treatment related toxicity other than neutropenia. Engraftment was successful. The patient experienced no graft-versus-host disease (GVHD) at any time but, on day 84 after transplantation, had a relapse in the central nervous system. Despite infusion of donor lymphocytes and intralumbar chemotherapy, she died on day 157 of systemic disease.

CONCLUSION

The reasons why treatment may have failed are discussed (nature of disease, disease progression, treatment schedule).

Cystectomy for severe hemorrhagic cystitis in allogeneic stem cell transplant recipients

BACKGROUND

Hemorrhagic cystitis (HC) is a common complication following allogeneic stem cell transplantation (SCT). In rare cases, it can be severe, inducing kidney failure and sepsis, and become life-threatening.

METHODS

We report three cases of severe HC in stem cell transplant recipients. Risk factors and the management of these patients were studied, as well as severe HC cases reported in the literature.

RESULTS

All three patients received high-dose cyclophosphamide in addition to total body irradiation or busulfan in their preparative regimen. They underwent allogeneic SCT, one of them from unrelated cord blood. BK viruria was detected in two cases at the onset of hematuria. HC lasted for more than 3 months, resulting in urinary tract obstruction and sepsis. Ultimately, cystectomy was the last therapeutic procedure available to treat this life-threatening complication.

CONCLUSION

We describe three patients, among a total of more than 1300 patients treated in our unit by allogeneic bone marrow transplantation, in whom HC was severe and long lasting enough to require cystectomy as a life-saving procedure.

Studies of serum and tissue maltases in the rat

Rat serum, kidney, and small bowel maltases were partially purified and chromatographed on columns of Sephadex G-200. Serum and kidney maltase migrated as early prominent peaks, whereas small bowel maltase separated into at least two and probably three peaks. No sucrase activity was present in either the serum or kidney peaks or in the first peak of small bowel maltase. The first maltase peak from small bowel and serum maltases had an optimal range of activity from pH 5.8 to 6.2. Kidney maltase activity was optimal at a narrow pH of 6.2. Heat inactivation studies suggested that at least two maltases were present in the chromatographic peaks of serum and kidney and in the first peak from small bowel. However, the velocity of inactivation of serum maltase differed from both kidney and small bowel maltases. Although serum, kidney, and some small bowel maltases may have similar chromatographic characteristics, the origin of serum maltase in the rat remains unclear.