Spontaneous gingival bleeding in an otherwise asymptomatic patient

This case is presented to challenge the reader to formulate a differential diagnosis for a patient who visits the dentist with spontaneous, continuous gingival bleeding. When this situation occurs, it is serious and requires immediate attention and a specific treatment plan to arrive at the underlying diagnosis and control the bleeding. The signs and symptoms of a patient with gingival bleeding are presented for diagnosis; the history and management are detailed, and may be useful in diagnosing and treating similar patients.

Tetraploidy in acute myeloid leukemia secondary to large cell lymphoma

A 67 year old male developed a therapy related myelodysplastic process culminating in acute myeloid leukemia 16 years following initial treatment for a large cell lymphoma. A second relapse of this leukemia showed 12% blasts including numerous giant blasts. The presence of giant blasts suggested the possibility of relapsed malignant lymphoma, however, flow cytometry and immunohistochemistry identified them as myeloid and chromosomal analysis revealed a near-tetraploid cell line. No evidence of lymphoma was seen. Although remission was induced with chemotherapy he subsequently relapsed with marrow and/or CNS involvement and was maintained on palliative therapy until he developed sepsis and died, 13 months following the observation of tetraploidy and 33 months following the onset of acute leukemia.

Allogeneic peripheral blood stem cell transplant for myelodysplasia after chemotherapy for post-transplant lymphoma in a cardiac transplant recipient at 10 years

A 32-year-old male received an allogeneic peripheral blood stem cell transplant (alloPBSCT) for myelodysplasia from his one HLA-A antigen mismatched brother. He is alive with trilineage engraftment and without active GVHD 200 days after transplant. In July 1986 he underwent orthotopic cardiac transplantation for viral cardiomyopathy and has received continuous immunosuppressive therapy. A post-transplant lymphoproliferative disorder with Hodgkin-like histopathology was diagnosed in August 1993 and was successfully treated with four cycles of MOPP chemotherapy. Due to persistent pancytopenia he underwent a bone marrow aspiration and biopsy in May 1996 which revealed monosomy 7 and morphologic changes compatible with myelodysplasia. This is the first report of a cardiac transplant recipient receiving an allogeneic hematopoietic stem cell transplant.

Relationship of CD34+ cell dose to early and late hematopoiesis following autologous peripheral blood stem cell transplantation

We evaluated early and late hematopoietic reconstitution in 27 patients with advanced lymphoma, Hodgkin's disease, and breast or ovarian cancer after treatment using high-dose/myeloablative conditioning regimens and autologous peripheral blood stem cell PBSC) transplantation. Eighteen patients (67%) received G-CSF 5 micrograms/kg/day following chemotherapy and nine (33%) were mobilized using G-CSF alone. Each patient had 7 x 10(8) mononuclear cells (MNC) per kg collected. G-CSF was administered post-PBSC infusion. While all patients showed prompt granulocyte recovery by day 14, platelet recovery failed to occur in our (15%) heavily pretreated patients with non-Hodgkin's lymphoma. Retrospective analysis in 17 patients revealed that the infused number of CD34 surface antigen-positive cells correlated with time to granulocyte (r = 0.59, P = 0.012) and platelet (r = 0.58, P = 0.021) recovery. Patients receiving the higher numbers of CD34+ cells had consistently better hematologic parameters at 11 times examined. At 180 days post-transplant, the median Hb level was 124 g/l vs 88 g/l (P = 0.004); platelet count was 202 x 10(9)/l vs 25 x 10(9)/l (P = 0.004); and neutrophil count was 3100 x 10(6)/l vs 1400 x 10(6)/l (P = 0.15). Hemoglobin strongly correlated with the CD34+ cell dose at 360 days (r = 0.90, P = 0.01). We conclude that graft CD34+ cell content appears to be an indicator of the quality of late as well as early hematopoietic function.

Human herpesvirus 6: infection and disease following autologous and allogeneic bone marrow transplantation

Human herpesvirus 6 activity (HHV-6) was studied in 15 allogeneic and 11 autologous marrow transplantation patients. After transplantation, HHV-6 was isolated from the peripheral blood mononuclear cells of 12 of 26 patients (6 allogeneic and 6 autologous). All isolates were variant B. Eleven of 26 and 12 of 19 patients showed salivary shedding of HHV-6 DNA before and after transplantation, respectively. The antibody titer increased in 7 of 26 patients. Thus, 23 of 26 patients showed evidence of active HHV-6 infection either by virus isolation, salivary shedding, or increases in antibody titers. The fraction of saliva specimens positive in 19 patients was negatively associated with their antibody titers (P= .005). The proportion of cultures positive increased after transplantation (P = .007). Sinusitis was associated with HHV-6 isolation in autologous recipients (P= .002). In allogeneic patients, active human cytomegalovirus infection was associated with HHV-6 isolation (P = .04). No association was observed between HHV-6 infection and GVHD, pneumonia, delay in engraftment, or marrow suppression. Of the 120 clinical events analyzed in 26 patients, HHV-6 was defined as a probable cause of 16 events in 9 patients based on the propinquity of HHV-6 activity and the clinical event plus the absence of other identified causes of the event.

High-dose cyclophosphamide, carboplatin, and etoposide with autologous stem cell rescue in patients with breast cancer

This study was designed to establish the toxicity and response rates o observed with a combination of high-dose cyclophosphamide, carboplatin, and etoposide with stem cell rescue in patients with breast carcinoma. Eligibility criteria included metastatic or locally advanced breast carcinoma ; aged < or equal to 60 years; performance status Eastern Cooperative Oncology Group (ECOG) 0-1; and creatinine clearance > or equal to 65 ml/min. Chemotherapy consisted of cyclophosphamide 25 mg/kg i.v. X 4 days, etoposide 400 mg/m(2) i.v. X 4 days, and carboplatin 375 mg/m(2) X 4 days. Bone marrow or peripheral blood stem cells were reinfused 48 h after completion of chemotherapy. Seventeen patients were treated in this study. The major toxicity was gastrointestinal (grades I and II). Fevers associated with neutropenia were observed in all the patients, but no episodes of bacteremia were documented. Hematopoietic toxicities were acceptable. No toxic deaths were observed. Six patients had chemotherapy-sensitive disease at time of transplant, nine had refractory disease, and two were untested. A response rate of 62% with 18% complete response (CR) was achieved. Two patients are free of disease at +7 and +9 months after transplantation. The combination of high-dose cyclophosphamide, carboplatin, and etoposide is well tolerated with a response rate comparable to previously reported high-dose chemotherapy regimens. However, in a poor prognostic risk group, namely patients with chemoinsensitive disease, this therapeutic approach seems to be of no advantage over standard chemotherapy.

Toxicity of busulfan and cyclophosphamide (BU/CY2) in patients with hematologic malignancies

Between July 1991 and January 1994, 52 patients with hematologic malignancies underwent BMT using BU/CY2 as conditioning regimen. Median patient age was 38 years. Eleven patients underwent autologous BMT, 22 HLA-identical allogeneic BMT, and 19 patients underwent a MUD or an allogeneic mismatched BMT. GVHD prophylaxis was with cyclosporine/methylprednisone in 26 patients; T cell depletion was used in 15 patients. VOD was observed in 7.5% of patients, IP in 12%, seizures in 4%. The overall incidence of grade II-IV acute GVHD was 35%. Delayed platelet engraftment was observed in seven of 11 patients who underwent autologous BMT. Graft failure was seen in seven of 19 (37%) patients who underwent MUD or allogeneic mismatched BMT. Six of the seven patients received T cell depletion as GVHD prophylaxis. BU/CY2 transplantation from an unrelated or family-mismatched donor with T cell depletion is associated with a high incidence of graft failure.

Late graft failure due to dual bone marrow infection with variants A and B of human herpesvirus-6

Hematopoietic effects of human Herpesvirus-6 (HHV-6) infection following bone marrow transplantation (BMT) include delayed engraftment and early myelosuppression. Variant A has not been isolated after BMT. A case of graft failure is reported following an HLA-identical BMT for chronic myelogenous leukemia (CML) in chronic phase. Evaluation of bone marrow during the period of graft failure revealed variants A and B of HHV-6 by culture, immunofluorescence, polymerase chain reaction (PCR), and immunohistochemistry. Evidence for other cases of graft failure, including cytomegalovirus (CMV), could not be found. A hypothesis is proposed that late graft failure in this case was due to variant A of HHV-6.

Autologous peripheral blood stem cell transplantation and adoptive immunotherapy with activated natural killer cells in the immediate posttransplant period

Relapse after high-dose chemotherapy supported by peripheral blood stem cell transplantation (HDC-PBSCT) is the main cause of therapeutic failure in patients with lymphoma and breast cancer. Adoptive immunotherapy with activated natural killer (A-NK) cells and interleukin 2 might eliminate surviving residual tumor without adding to toxicity. Eleven patients with relapsed lymphoma and one with metastatic breast cancer were entered on a pilot clinical trial of HDC-PBSCT followed on day 2 after transplant by infusion of cultured autologous A-NK cells. Simultaneously, recombinant human interleukin 2 (rhIL-2) was initiated as a 4-day continuous i.v. infusion at 2 x 10(6) IU/m2/day, referred to as high-dose rhIL-2. Therapy with high-dose rhIL-2 was followed by a 90-day continuous i. v. infusion at 3 x 10(5) IU/m2/day, referred to as low-dose rhIL-2. All patients engrafted and nine completed treatment. Posttransplant days to a neutrophil count of 500/microliter and to a platelet count of 50,000/microliter were similar to comparable patients treated with HDC-PBSCT alone. Generation of A-NK cells for therapy was feasible in all patients except the three patients with Hodgkin's disease, whose cells did not proliferate in culture. Overall toxicity associated with early posttransplant transfer of A-NK cells and interleukin 2 did not differ from that observed with peripheral blood stem cell transplantation alone in comparable patients. There was early amplification of natural killer cell activity in the peripheral blood of four patients that appeared to result from the transfused A-NK cells. Adoptive transfer of A-NK cells and rhIL-2 during the pancytopenic phase after HDC-PBSCT was feasible and well tolerated, did not adversely affect engraftment, and resulted in amplified natural killer activity in the peripheral blood during the immediate posttransplantation period.

Hematopoietic progenitor cell content of vertebral body marrow used for combined solid organ and bone marrow transplantation

While cadaveric vertebral bodies (VB) have long been proposed as a suitable source of bone marrow (BM) for transplantation (BMT), they have rarely been used for this purpose. We have infused VB BM immediately following whole organ (WO) transplantation to augment donor cell chimerism. We quantified the hematopoietic progenitor cell (HPC) content of VB BM as well as BM obtained from the iliac crests (IC) of normal allogenic donors (ALLO) and from patients with malignancy undergoing autologous marrow harvest (AUTO). Patients undergoing WO/BM transplantation also had AUTO BM harvested in the event that subsequent lymphohematopoietic reconstitution was required. Twenty-four VB BM, 24 IC BM-ALLO, 31 IC AUTO, and 24 IC WO-AUTO were harvested. VB BM was tested 12 to 72 hr after procurement and infused after completion of WO grafting. IC BM was tested and then used or cryopreserved immediately. HPC were quantified by clonal assay measuring CFU-GM, BFU-E, and CFU-GEMM, and by flow cytometry for CD34+ progenitor cells. On an average, 9 VB were processed during each harvest, and despite an extended processing time the number of viable nucleated cells obtained was significantly higher than that from IC. Furthermore, by HPC content, VB BM was equivalent to IC BM, which is routinely used for BMT. We conclude that VB BM is a clinically valuable source of BM for allogeneic transplantation.

A unique population of CD34+ cells in cord blood

Human umbilical cord blood (CB) is a rich source of hematopoietic stem cells for both research and stem cell transplantation. In clinical studies, it appears that recovery from myeloablative therapy using CB requires significantly fewer cells than a typical allogeneic marrow transplant. This suggests that CB may be enriched for early hematopoietic progenitors. The present studies were undertaken to determine the presence of CD34+ cells in CB with the phenotypic characteristics of multipotential stem cells. In 22 CB harvests, the average percentage of CD34+ cells was 1.33 +/- 0.21% (SE), a value similar to that in adult normal bone marrows (BM). However, the distribution of CD34+ cells was distinctly different from either BM or granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cell harvests. CB contained a defined population of brightly staining CD34+ cells with low side scatter. These CD34 (bright) cells comprised a mean of 14.5 +/- 2.5% of the CB CD34+ cells, whereas < 1% of BM CD34+ cells has been shown to be CD34- bright. Eighty-five to ninety percent were negative for three antigens expressed at an early stage of stem cell maturation: CD38, HLA-DR and LFA-1. Fifty-five percent of these CD34 (bright) cells did not express the CD45RA isoform, an additional marker of immaturity. The antigen-bright cells also lacked lineage-specific antigens including CD33, CD56, CD19, CD10 and CD7 as well as CD71. Approximately 46% were Thy-1+, and 40% expressed c-kit receptors. These data suggest that, by phenotypic criteria, CB may be a particularly enriched source of primitive hematopoietic precursors.

Reversible cyclosporine-induced cortical blindness in allogeneic bone marrow transplant recipients

We report the occurrence of reversible cyclosporine-induced cortical blindness in three allogeneic bone marrow transplant recipients. Possible mechanisms involved in this rare complication, as well as the associated radiographic and pathologic findings, are discussed.

Augmentation of chimerism in whole organ recipients by simultaneous infusion of donor bone marrow cells

We had previously demonstrated the persistence of donor leukocytes in the peripheral blood and tissues of long-surviving kidneyl and live2 -4 recipients who had stable graft function many years after transplantation.1 -6 Donor cell chimerism has since been noted by other investigators in recipients of heart,7 liver,8 kidney,9 and lungl0 transplants. In an attempt to augment chimerism, and thereby facilitate graft function, we initiated a prospective trial to enhance this phenomenon by infusing 3 × l08/kg unaltered donor bone marrow cells perioperatively into an unmodified recipient of whole organ from the same donor. Additionally, 53 recipients of whole organ alone were monitored as controls. Reported herein are the first 20 of 64 study patients and 33 of 53 control patients who are more than 120 days posttransplantation.

Enumeration of CD34+ hematopoietic stem cells for reconstitution following myeloablative therapy

The CD34+ cell fraction of bone marrow and blood contains the hematopoietic stem cells required for marrow reconstitution following myeloablative therapy. Because they are present in small numbers, accurate quantification is often difficult. We have developed a reproducible and sensitive flow cytometric method for CD34+ enumeration of both bone marrow harvests and peripheral blood stem cell collections. The total numbers of harvested cells are enumerated by particle counting. A measured aliquot is stained with two FITC-labeled anti-CD34 antibodies, one directed against 8G12 and the other against QBend epitope. To eliminate cells committed to mature lineages (lin+), the suspension is counterstained with a cocktail of PE-labeled antibodies including CD3 (T cells), CD19 (B cells), CD11b (neutrophils), and CD14 (monocytes). Particles < 6 microns in diameter are excluded by use of a standard bead gate. Regions are established using unstained U937 cells to set the vertical axis and PE stained U937 cells for the horizontal axis. Because of the low numbers of CD34+ cells, 20,000 events/sample are analyzed. Dilutions of KG-1A tumor cells (CD34+) in U937 cells showed a threshold of detection of 0.1% CD34+lin- cells. Duplicate samples varied by < 10%. Initial studies indicate that this procedure can be reliably used to measure CD34+lin- cells in blood, pheresis products, and bone marrow harvests. This CD34 enumeration procedure should result in increased consistency in enumerating this stem cell population.

Amplification of the graft-versus-host reaction by cyclophosphamide: dependence on timing of drug administration

An experimental model, previously developed to study the combined effect of partial body irradiation and the graft-versus-host (GVH) reaction, has been adapted to assay the amplification of the GVH reaction by cyclophosphamide (CY). The system has proved sensitive enough to detect differences in the level of the GVH reaction produced by relatively small changes in pre-transplant conditioning. F1 hybrid mice treated with either CY 60 mg/kg or allogeneic (parental) lymphoid cells (ALC, 20 x 10(6)) had 100% survival. In contrast, ALC given 24 h after CY injection resulted in 84% GVHD-related mortality with a mean survival time of 18 days. Amplification of the GVH reaction by CY was also seen in terms of splenomegaly and immunosuppression. Separation of CY and ALC injection by an interval longer that 24 h reduced the severity of GVH reaction but some amplification was still observed. Based on several GVHD-related criteria, experimental groups with a 2 or 4 day interval between CY and ALC injection had approximately the same response, an effect was still detectable for an interval of 7 days between injections but was no longer apparent when the interval was extended to 12 days.

Reversal of graft-versus-host disease with infusion of autologous bone marrow

Graft-versus-host disease (GVHD) remains a major complication of bone marrow transplantation. This report describes reversal of GVHD by infusion of stored recipient bone marrow following combined liver-bone marrow allotransplantation. Graft-versus-host disease developed at the end of the first postoperative week. The skin involvement progressively spread to approximately 80% of the body surface and was not affected by modification of the immunosuppressive treatment. On the 42nd and 43rd postoperative day 1.23 x 10(8) and 1.6 x 10(8) autologous bone marrow cells per kg of recipient body weight were infused. The skin rush began to dramatically improve and resolved within 2 wk from the autologous marrow infusion. Autologous bone marrow storage previous to allogeneic bone marrow transplantation for tolerance induction could constitute a safety net in case of occurrence of GVHD.

Autologous bone marrow transplantation for adult acute leukemia

In this review we have considered the role of ABMT for the acute leukemias. It is apparent from data around the world that ABMT is a curative therapy for patients with both AML and ALL after primary treatment failure. Other than allogeneic BMT, ABMT may be the only curative therapy following relapse, especially in AML. The role of ABMT in first CR is less well defined. There are few data to support the widespread use of ABMT in first CR for ALL. Moreover, the improved survival of adults with ALL with current intense multiagent regimens will probably obviate the need to continue clinical trials of ABMT for ALL in first CR. For patients with AML in first CR, however, it seems that ABMT may well lead to improved rates of DFS compared with chemotherapy alone. Almost every published report describes better DFS for patients who underwent ABMT compared with historical or contemporary controls who were treated with chemotherapy. One note of caution is that as chemotherapy evolves, the increment in survival currently observed from ABMT may diminish, thus rendering ABMT less obviously necessary. On the other hand, from an economic standpoint, ABMT could prove to be cost-effective, because a short, intense treatment that is effective may prove to be less costly than the current extended period of chemotherapy. Because ABMT is becoming safer, it would seem reasonable to continue its use in patients with AML at high risk for relapse (secondary AML, adverse cytogenetics, and so on) while awaiting the outcome of the randomized clinical trials currently underway that are seeking to define the role of ABMT for the general population of patients with AML after initial remission is achieved. Meanwhile, further definition of the relative value of the various purging regimens, preparative regimens, and adjunctive therapy (i.e., IL-2, mAb) warrants study.

A comparison of clinical criteria for the diagnosis of veno-occlusive disease of the liver after bone marrow transplantation

Two major studies have established clinical criteria for the diagnosis of veno-occlusive disease of the liver (VOD) after bone marrow transplantation (BMT). McDonald and co-workers defined VOD as the onset of two of the following occurring before day 30 post-BMT: (a) jaundice (bilirubin > 27 mmol/l), (b) tender hepatomegaly, and (c) ascites or weight gain. In contrast, Jones and co-workers defined VOD as the onset, before day 21 post-BMT, of hyperbilirubinemia (bilirubin > 34 mmol/l) as well as two of the following: (a) hepatomegaly, (b) ascites, and (c) weight gain. We retrospectively reviewed the occurrence of VOD in 101 patients transplanted primarily for hematologic malignancies between 1979 and 1990, applying both sets of criteria. Of the 101 patients, eight (7.9%) fulfilled the Jones criteria whereas 32 (31.7%) had VOD according to the McDonald criteria (p < 0.001). Early mortality (prior to 50 days post-BMT) was 75% (6/8) in patients who fulfilled the Jones criteria but only 28.1% (9/32) in the McDonald group (p < 0.005). Overall, mortality in each group was 75% (6/8) and 65.6% (21/32), respectively. All of the six patients with VOD according to the Jones criteria who died had evidence of hepatic failure. Of the 32 patients who fulfilled the McDonald criteria, eight have also fulfilled the Jones criteria and are described above. Of the remaining 24 patients, 22 had complete resolution of VOD as defined by these criteria within 50 days of BMT, none developed hepatic failure, and 15 died.(ABSTRACT TRUNCATED AT 250 WORDS)

Allogeneic bone marrow transplantation using unrelated donors: a pilot study of the Canadian Bone Marrow Transplant Group

Between February 1988 and January 1990, 35 patients underwent allogeneic bone marrow transplantation (BMT) from unrelated donors using measures routinely employed for matched related donors. Median patient age was 34 years (range 2-49). Thirty-two patients had hematologic malignancies, including chronic myelogenous leukemia (CML) in 16; three patients had severe aplastic anemia. Donor-patient pairs were matched at the HLA loci tested serologically (HLA-A, -B, -DR) in 29 cases; mixed leukocyte culture results were variable but often reactive. Five patients died prior to day +28 without evidence of myeloid engraftment, and one patient developed fatal graft failure several months after initial engraftment. Acute graft-versus-host disease (GVHD) occurred in 77% (95% confidence interval [CI] 60-90%) of all patients, and GVHD contributed to the death of 10 patients. Fatal regimen-related toxicity occurred in four patients and another died due to neurologic complications of a process that resembled the hemolytic-uremic syndrome. Two acute leukemia patients relapsed, and a CML patient was found to have a localized non-Hodgkin's lymphoma at necropsy. As of 1 June 1991, 14 patients are alive and in remission at a median follow-up of 1.9 years (range 1.5-3.3); all except one have normal performance scores. The 2-year actuarial event-free survival for all patients is 40% (95% CI 24-56%). Proportional hazards analysis revealed favorable significance for female patient sex, less advanced disease status and shorter interval from diagnosis to BMT. While unrelated-donor transplants need not necessarily duplicate the results of related-donor transplants to be of benefit, the event-free survival in this series was roughly similar to that expected in the related-donor situation, with the high transplant-related mortality somewhat offset by a low recurrence rate. Further studies using unrelated donors, employing new methods of preventing transplant-related complications, are indicated.

Reducing parenteral energy and protein intake improves metabolic homeostasis after bone marrow transplantation

The purpose of this prospective study was to compare the metabolic effects of reducing parenteral energy and protein intake in bone-marrow-transplant (BMT) patients from 150% (hi-TPN group) to 100% (lo-TPN group) basal energy expenditure. Cytotoxic therapy was given on days 1-5, BMT on day 6, and TPN beginning on days 6 or 7. The lo-TPN group exhibited higher serum albumin (38 +/- 0.4 vs 32 +/- 0.4 g/L, P less than 0.01) but similar nitrogen balance (-83 +/- 8 vs -86 +/- 8 mg.kg-1.d-1, P greater than 0.05). Serum Na+ remained greater than 134 +/- 1 mmol/L in the lo-TPN group but fell to 127 +/- 1 mmol/L in the hi-TPN group (P less than 0.001) despite similar Na+ intakes and balances. Serum K+ remained less than 4.4 +/- 0.2 mmol/L in the lo-TPN group but rose to 5.1 +/- 0.1 mmol/L in the hi-TPN group (P less than 0.01) despite similar K+ intakes and balances. Delivering TPN at lower-than-normal rates after BMT appears to minimize Na+ and K+ disturbances and improve serum albumin concentrations without having any adverse effect on nitrogen balance.

The use of CT densitometry to predict lung toxicity in bone marrow transplant patients

Total body irradiation (TBI) is considered an integral part of the preparation of patients with hematological malignancies for marrow transplantation. One of the major causes of death following bone marrow transplantation is interstitial pneumonia. Its pathogenesis is complex but radiation may play a major role in its development. Computed tomography (CT) has been used in animal and human studies as a sensitive non-invasive method for detecting changes in the lung following radiotherapy. In the present study CT scans are studied before and up to 1 year after TBI. Average lung densities measured before TBI showed large variations among the individual patients. On follow-up scans, lung density decreases were measured for patients who did not develop lung complications. Significant lung density increases were measured in patients who subsequently had lung complications. These lung density increases were observed prior to the onset of respiratory complications and could be correlated with the clinical course of the patients, suggesting the possibility for the usage of CT lung densitometry to predict lung complications before the onset of clinical symptoms.

Amplification of the graft-versus-host reaction by partial body irradiation

An experimental model has been developed for the study of combined effects of partial body irradiation (PBI) and graft-versus-host disease (GVHD) in which irradiation is delivered to the thorax 24 hr prior to induction of GVHD in hybrid mice by the injection of parental lymphoid cells. In mice irradiated to 1000 cGy or exposed to low doses of allogeneic lymphoid cells (20 X 10(6)), survival was 100% at 250 days. In contrast, combination of the two treatments, GVHD and PBI, resulted in a mortality of 83% and a mean survival time of 29 days, indicating synergy between GVHD and PBI. From histological studies of the lung it appeared that about 40% of the deaths occurring after combined GVHD/PBR treatment might be attributable to pneumonia. The cause of death in the remaining mice receiving combined treatment is not known. Mice receiving combined PBI/lymphoid cell treatment develop a characteristic skin lesion that is not seen in nonirradiated mice and is confined to the irradiated area. The effect of preinduction PBR on the timing and severity of GVHD is similar to that which would be produced by an increase in the number of effector cells.

Radiation response of haematopoietic cell lines of human origin

Six human haematopoietic cell lines, five of leukaemic origin, including cells with myeloid, lymphoid and undifferentiated phenotype have been studied with respect to radiation response. The intrinsic radiosensitivity of the cells varied widely, the D0s ranging from 0.53 to 1.39 Gy. Five of the cell lines showed some capacity to accumulate sublethal damage; in three of these, enhanced survival was demonstrated in split-dose experiments. One cell line (HL-60) was anomalous in that although little accumulation of sublethal damage was demonstrable, survival was enhanced by fractionation of the dose. Five of the six cell lines studied were of leukaemic origin. The results support the belief that, in contrast to the almost constant radiosensitivity of normal haematopoietic cell progenitors, leukaemic cell progenitors may show a wide range of radiosensitivites.

Dose rate dependence of response of mouse lung to irradiation

The dose-rate dependence of lung damage in mice has been studied using LD50/50-180 as an index of the incidence of radiation pneumonitis. Mean lethal doses for 60Co gamma radiation to the thorax delivered at 100, 25 and 6 cGy/min were 1403, 1923 and 2488 cGy respectively. There were statistically significant differences between values obtained at 6 and 25 cGy/min and between those obtained at 25 and 100 cGy/min. An isoeffect plot of this data on a log-log graph shows the sparing effect of dose rate reduction to be greater for the lung than for more rapidly responding systems (colony forming units of small intestine and Chinese hamster cells in culture).

Interstitial pneumonitis following total body irradiation for bone marrow transplantation using two different dose rates

A total of 22 patients with leukemia (10 ALL, 11 AML, 1 CML) have undergone allogeneic bone marrow transplantation (BMT) by the Quebec Co-operative Group for Marrow Transplantation from 1980 to 1982. All patients received 900 cGy total body irradiation (TBI), in a single fraction, on the day preceding BMT. The first 11 patients were treated on a cobalt unit at a constant dose rate of 4.7 to 6.3 cGy/min. Six of these patients developed interstitial pneumonitis (IP). The clinical course of three patients, two with idiopathic and one with drug-induced pneumonitis, was mild and recovery was complete in all. The other three patients developed severe infectious IP and two died. The next 11 patients were treated with a sweeping beam technique on a 4 MV linear accelerator delivering a total tumor dose of 900 cGy at an average dose rate of 6.0 to 6.5 cGy/min but an instantaneous dose rate of 21.0 to 23.5 cGy/min. Eight patients developed severe IP. Five of these were idiopathic and four died. Three were infectious and all died. The fatality of interstitial pneumonitis appeared to be greater in the group treated with the sweeping beam technique.