Prior COVID-19 infection may increase risk for developing endothelial dysfunction following hematopoietic cell transplantation

Endothelial dysfunction underlies many of the major complications following hematopoietic cell transplantation (HCT), including transplant-associated thrombotic microangiopathy (TA-TMA), veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), and engraftment syndrome (ES). Emerging evidence similarly implicates endothelitis and microangiopathy in severe COVID-19-related multi-system organ dysfunction. Given the overlap in these two illness states, we hypothesize that prior COVID-19 infection may increase risk for HCT-related endotheliopathies. This retrospective, multicenter study included patients aged 0-25 years who underwent autologous or allogeneic HCT for any indication between January 1, 2020 and September 21, 2021, with close attention to those infected with COVID-19 in either the six months prior to transplant or twelve months following transplant. Incidences of TA-TMA, VOD/SOS, and ES were compared among patients with COVID-19 infection pre-HCT and post-HCT, as well as with historical controls who were never infected with SARS-CoV-2. Those who underwent HCT following COVID-19 infection displayed significantly increased rates of TA-TMA compared to those who were never infected. Additionally, our data suggests a similar trend for increased VOD/SOS and ES rates, although this did not reach statistical significance. Therefore, a history of COVID-19 infection prior to undergoing HCT may be a nonmodifiable risk factor for endothelial-related complications following HCT. Further studies are warranted to better clarify this relationship among larger cohorts and in the era of the Omicron SARS-CoV-2 variants.

What Is Different in Acute Hematologic Malignancy-Associated ARDS? An Overview of the Literature

Background and Objectives: Acute hematologic malignancies are a group of heterogeneous blood diseases with a high mortality rate, mostly due to acute respiratory failure (ARF). Acute respiratory distress syndrome (ARDS) is one form of ARF which represents a challenging clinical condition. The paper aims to review current knowledge regarding the variable pathogenic mechanisms, as well as therapeutic options for ARDS in acute hematologic malignancy patients. Data collection: We provide an overview of ARDS in patients with acute hematologic malignancy, from an etiologic perspective. We searched databases such as PubMed or Google Scholar, including articles published until June 2022, using the following keywords: ARDS in hematologic malignancy, pneumonia in hematologic malignancy, drug-induced ARDS, leukostasis, pulmonary leukemic infiltration, pulmonary lysis syndrome, engraftment syndrome, diffuse alveolar hemorrhage, TRALI in hematologic malignancy, hematopoietic stem cell transplant ARDS, radiation pneumonitis. We included relevant research articles, case reports, and reviews published in the last 18 years. Results: The main causes of ARDS in acute hematologic malignancy are: pneumonia-associated ARDS, leukostasis, leukemic infiltration of the lung, pulmonary lysis syndrome, drug-induced ARDS, radiotherapy-induced ARDS, diffuse alveolar hemorrhage, peri-engraftment respiratory distress syndrome, hematopoietic stem cell transplantation-related ARDS, transfusion-related acute lung injury. Conclusions: The short-term prognosis of ARDS in acute hematologic malignancy relies on prompt diagnosis and treatment. Due to its etiological heterogeneity, precision-based strategies should be used to improve overall survival. Future studies should focus on identifying the relevance of such etiologic-based diagnostic strategies in ARDS secondary to acute hematologic malignancy.

Endothelial Dysfunction after Hematopoietic Stem Cell Transplantation: A Review Based on Physiopathology

Endothelial dysfunction (ED) is frequently encountered in transplant medicine. ED is an argument of high complexity, and its understanding requires a wide spectrum of knowledge based on many fields of basic sciences such as molecular biology, immunology, and pathology. After hematopoietic stem cell transplantation (HSCT), ED participates in the pathogenesis of various complications such as sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), graft-versus-host disease (GVHD), transplant-associated thrombotic microangiopathy (TA-TMA), idiopathic pneumonia syndrome (IPS), capillary leak syndrome (CLS), and engraftment syndrome (ES). In the first part of the present manuscript, we briefly review some biological aspects of factors involved in ED: adhesion molecules, cytokines, Toll-like receptors, complement, angiopoietin-1, angiopoietin-2, thrombomodulin, high-mobility group B-1 protein, nitric oxide, glycocalyx, coagulation cascade. In the second part, we review the abnormalities of these factors found in the ED complications associated with HSCT. In the third part, a review of agents used in the treatment of ED after HSCT is presented.

Immunological Adverse Events After Autologous Hematopoietic Stem Cell Transplantation in Systemic Sclerosis Patients

Autologous hematopoietic stem cell transplantation (aHSCT) represents an effective treatment for systemic sclerosis (SSc), but it also can cause immunological adverse events (iAEs). Therefore, we aimed to determine the frequency of iAEs [engraftment syndrome (ES) and secondary autoimmune disorder (sAD)] and to identify potential risk factors for their development in a retrospective analysis on 22 patients similarly transplanted due to SSc. While nine patients (41%) suffered from ESs, seven sADs occurred in six patients (27%). Patients who developed ES were older in our cohort (52.45 vs. 42.58 years, p = .0433, Cohen’s d = 0.86), and cardiac involvement by SSc was associated with development of ES (OR = 40.11, p = .0017). Patients with manifestation of sAD had a higher modified Rodnan skin score (mRSS) reduction after aHSCT (90.50% vs. 60.00%, p = .0064, r = .65). Thus, IAEs are common after aHSCT for SSc and can occur in different stages during and after aHSCT with characteristic clinical manifestations. Good cutaneous response after aHSCT might be considered as a risk factor for sAD, and higher age at aHSCT and cardiac involvement might be considered as risk factors for the development of ES.

Pretransplant Risk Factors Can Predict Development of Acute Respiratory Distress Syndrome after Hematopoietic Stem Cell Transplantation

Rationale: Acute respiratory distress syndrome (ARDS) is a common complication after hematopoietic stem cell transplantation (HCT) and is a major contributor to nonrelapse mortality. Objectives: To better understand pretransplant risk factors for developing ARDS after HCT. Methods: This is a single-center observational study comparing risk factors for ARDS development in 164 patients who went on to develop post-HCT ARDS compared with 492 patients who did not. The patients were matched 1 to 3 on age, sex, type of transplant (allogeneic vs. autologous), and underlying disease. Pertinent risk factors were analyzed separately in multivariable conditional logistic regression after adjustment for a priori variables known to be associated with ARDS development. Results: Patients with ARDS were more likely to have a lower pretransplant pulmonary function as measured by forced vital capacity (FVC) (odds ratio [OR], 0.54 [0.42-0.70] per liter increase in FVC; P < 0.001), forced expiratory volume in one second (FEV₁) (OR, 0.52 [0.38-0.71] per liter increase in FEV₁; P < 0.001) and diffusing capacity (OR, 0.92 [0.88-0.96] per ml/min/mm Hg increase in diffusing capacity; P < 0.001). Several laboratory indices were predictive of subsequent ARDS development including elevated AST (aspartate aminotransferase) (OR, 1.01 [1.00-1.01]; P < 0.008), lower serum albumin (OR, 0.44 [0.30-0.66]; P < 0.001), lower pretransplant hemoglobin (OR, 0.82 [0.73-0.92]; P = 0.001), and lower leukocyte count (OR, 0.88 [0.79-0.99]; P < 0.03). Patients who went on to develop ARDS were more likely to have been hospitalized in the year before the transplant (OR, 1.11 [1.04-1.20]; P = 0.003), and required invasive or noninvasive ventilation during that hospitalization. Lastly, patients with ARDS were significantly more likely to have received carboplatin, thalidomide, methotrexate, and cisplatin than the non-ARDS control subjects. Conclusions: Several risk factors for developing ARDS after HCT are identifiable at the time of transplantation, well before the development of critical illness and ARDS. The identification of risk factors long before ARDS develops is relatively unique to the HCT population. Further work is needed to develop usable risk prediction tools in this setting.

Evaluating the incidence of engraftment syndrome with different melphalan formulations in adult multiple myeloma and immunoglobulin light chain amyloidosis patients undergoing autologous hematopoietic cell transplantation

BACKGROUND

Engraftment syndrome (ES) is a common complication of autologous hematopoietic cell transplantation (HCT). The difference in incidence of ES between melphalan formulations has not been widely reported throughout the literature and would allow for a more comprehensive understanding of the advantages and disadvantages of both melphalan formulations.

PATIENTS AND METHODS

This retrospective, single-center, observational study evaluated 83 adult multiple myeloma and immunoglobulin light chain amyloidosis patients who received either propylene glycol-containing (PG) or propylene glycol-free (PG-free) melphalan 140 mg/m² as single-agent conditioning chemotherapy for autologous HCT from May 31, 2015 to May 31, 2019. The primary outcome was to assess the incidence of ES, as defined using the Maiolino criteria, with both melphalan formulations. Secondary outcomes included an analysis of potential risk factors for the development of ES, as well as an evaluation of overall length of stay (LOS).

RESULTS

The incidence of ES for PG and PG-free melphalan did not differ significantly, 14/39 (35.9%) and 12/44 (27.3%) (P = 0.4), respectively. No potential risk factors for ES were identified on multivariate logistic regression analysis. A statistically significant difference in number of days to engraftment was identified for PG and PG-free melphalan, 15.56 vs. 13.82 days (P = 0.01), respectively; although, this did not translate to a decrease in LOS, 19.9 vs. 18.59 days (P = 0.14).

CONCLUSIONS

The incidence of ES did not differ significantly between melphalan formulations. Future research is needed to determine whether the faster time to engraftment seen with PG-free melphalan may translate to a decrease in LOS.

Outcome of Acute Respiratory Failure Secondary to Engraftment in Children After Hematopoietic Stem Cell Transplant

Introduction: Respiratory complications due to engraftment syndrome (ES) in the post-hematopoietic stem cell transplant (HSCT) setting can lead to acute respiratory failure (ARF). Outcomes of children developing ARF due to engraftment are unknown.

Methods: We conducted a retrospective analysis of 1,527 pediatric HSCT recipients and identified children who developed ARF due to ES over a 17-year period. Thirty patients that developed ARF and required invasive mechanical ventilation (IMV) due to ES were included in this study.

Results: The survival rate for our cohort was 80% [alive at intensive care unit (ICU) discharge]. The most common underlying primary disease was hematologic malignancy, and 67% of children underwent allogeneic HSCT. Further, 73% required vasopressor drips and 23% underwent dialysis. Survivors had a shorter median ICU length of stay than did non-survivors (15 vs. 40 days, respectively, p = 0.01). Survivors had a significantly lower median cumulative fluid overload % on days 4 and 5 after initiation of IMV than did non-survivors (2.8 vs. 14.0 ml/kg, p = 0.038 on day 4, and 1.8 vs. 14.9 ml/kg, p = 0.044 on day 5, respectively).

Conclusion: Our results suggest that children who develop ARF during engraftment have better ICU survival rates than do those with other etiologies of ARF post-HSCT. Furthermore, fluid overload contributes to mortality in these children; therefore, strategies to prevent and address fluid overload should be considered.

Prophylactic corticosteroid use prevents engraftment syndrome in patients after autologous stem cell transplantation

Engraftment syndrome (ES) following autologous stem cell transplantation (ASCT) at the time of neutrophil recovery may comprise fever, rash, pulmonary edema, or diarrhea. Usually, ES is easily manageable using corticosteroids but may prolong hospitalization. In two consecutive cohorts of subsequent patients with myeloma, lymphomas, and testicular/germ cell cancer, we assessed the benefit of corticosteroid use to prevent incidence and severity of ES following ASCT. Whereas Cohort A (82 patients) received no prophylactic corticosteroids, corticosteroids (4 mg dexamethasone oral daily) were started in Cohort B (60 patients) at day +9 until day +13 following ASCT. Steroid prophylaxis significantly reduced the incidence of ES (6/60; 10% vs. 33/82; 40%; p < 0.001). Hospitalization duration was longer in patients with ES than in patients without ES within both cohorts (in Cohort A: p = 0.007; and B: p = 0.011), but did not differ significantly between cohorts A and B. Finally, in Cohort A, there was a trend to an inferior 2-year overall survival rate in patients without ES compared to patients with ES (p = 0.067), but definite conclusions are not yet allowed. Our results suggest that corticosteroid prophylaxis from days +9 to +13 following ASCT significantly reduces the risk of ES and shortens hospitalization duration.

Chemotherapy-induced pulmonary complications in cancer: Significance of clinicoradiological correlation

Chemotherapy while revolutionizing cancer management by improving survival and quality of life; is also associated with several adverse effects. Lung is the most common organ affected in chemotherapy-related complications, due to either drug toxicity or more commonly due to infections caused by immunosuppression and less commonly due to immune-mediated injury. Radiology, when used in combination with clinical and lab data, can help reach the specific diagnosis or narrow down the differentials. The common radiological patterns of drug toxicity include pulmonary interstitial and airway infiltrates, diffuse alveolar damage, nonspecific interstitial pneumonia, eosinophilic pneumonia, cryptogenic organizing pneumonia, pulmonary hemorrhage, edema and hypertension. Cancer patients are immunosuppressed due to the underlying malignancy itself or due to therapy and are prone to a gamut of opportunistic infections including viral, bacterial, fungal and mycobacterial pathogens. Immune reconstitution inflammatory syndrome (IRIS), a well-known complication in HIV, is now being increasingly recognized in non-HIV patients with immunosuppression. Engraftment syndrome is specifically seen following hematopoietic stem cell transplant during neutrophil recovery phase. Pulmonary involvement is frequent, causing a radiological picture of noncardiogenic pulmonary edema. Thus, radiology in combination with clinical background and lab parameters helps in detecting and differentiating various causes of pulmonary complications. This approach can help alter potentially toxic treatment and initiate early treatment depending on the diagnosis.

Engraftment Syndrome and Acute Graft-versus-Host Disease: A Meta-Analysis

Engraftment syndrome (ES) has been associated with the surge of neutrophils and cytokines, which is similar to the presumed underlying pathophysiology behind acute graft-versus-host disease (aGVHD). However, there has been no meta-analysis to evaluate the association; therefore, the team attempted to verify an association between ES and aGVHD through meta-analysis. The team searched for titles of articles in MEDLINE (PubMed), the Cochrane Library, and the EMBASE database up until December 2018 that evaluated the association between ES and aGVHD and conducted a random effect meta-analysis of 8 studies involving a total of 1,945 participants to report the pooled odds ratio (OR) for association of ES and aGVHD. The team found a significantly increased odds of developing aGVHD in patients with ES with the pooled OR of 2.76 (95% confidence interval [CI]: 1.64-4.63) and an I²⁼ 64.5%. In conclusion, patients with ES have significantly higher odds of developing aGVHD compared to patients without ES.

Incidence and characteristics of engraftment syndrome after autologous hematopoietic cell transplantation in light chain amyloidosis

Engraftment syndrome (ES), a complication of autologous hematopoietic cell transplantation (auto-HCT), can occur around the time of neutrophil recovery. We sought to identify the incidence of ES in light chain (AL) amyloidosis patients undergoing auto-HCT at our centre by evaluating 72 consecutive amyloidosis patients transplanted between 1999 and 2017. To assess trends in ES over time, patients were divided into two Eras (Era 1 = 1999-2008 and Era 2 = 2009-2017) based on year of auto-HCT. Twenty-two (31%) patients developed ES; three (16%) and 19 (36%) in Era 1 and 2, respectively (p = .1). Three (16%) and 51 (96%) patients in Era 1 and 2 received chemotherapy before auto-HCT (p =  <.001). The most common symptoms observed with ES in addition to fever was diarrhoea (73%), rash (68%), weight gain (56%) and non-cardiogenic pulmonary oedema (23%). Day 100 post-auto-HCT haematological response (19.5% vs. 14%, p = .7) or post-transplant best organ response (23% vs. 36%, p = .2) were not significantly different in patients who did not or did develop ES, respectively. In this single centre series, we define the incidence and characteristics of ES in AL amyloidosis patients undergoing auto-HCT.

Neutropenic Fever

Neutropenia is defined as an abnormally low absolute neutrophil count (ANC) and can be further delineated as severe or profound (see below). Recipients of chemotherapy will often have a decreased ANC leading to an increased risk of infections specifically from bacterial sources. Neutropenia traditionally is risk stratified based on duration and depth of neutropenia. Recipients of chemotherapy for acute myelogenous leukemia (AML) and stem cell transplants (SCTs) often are deemed as having high risk neutropenia due to significant depth and duration of neutropenia. The mortality associated with febrile neutropenia is up to 11%, and can be as high as 50% in the setting of severe sepsis or septic shock. By risk stratifying neutropenia and the resultant neutropenic fever, the goal is to decrease the resultant morbidity and mortality (Taplitz et al., J Clin Oncol 36:3043–3054).

Procalcitonin and cytokine profiles in engraftment syndrome in pediatric stem cell transplantation

BACKGROUND

Diagnosis of engraftment syndrome (ES) following allogeneic hematopoietic stem cell transplantation (HSCT) can be a challenge due to the systemic presentation and alternative etiologies. With a goal of establishing biomarkers to more accurately distinguish ES, we prospectively analyzed levels of cytokines during HSCT.

PROCEDURES

We performed a prospective study of children ≤21 years who underwent allogeneic HSCT. Blood samples for interleukin (IL)-6, IL-8, IL-10, IL-1b, IL-12p70, interferon-γ, tumor necrosis factor alpha (TNF-α) and procalcitonin were obtained from each subject prior to conditioning, at day 0, and then biweekly through engraftment and at days 30, 60 and 100. Patients were evaluated for ES, infection and acute graft-versus-host disease. Cytokines were analyzed by values at engraftment, and also compared to pre-conditioning and day 0 values to evaluate for change from baseline.

RESULTS

A total of 30 subjects (median age: 7 years, min.-max.: 1-21 years) were enrolled of whom 5 had ES. Characterization of the cytokine profile revealed differences between day 0 from pre-HSCT, with a trend towards differences in IL-10, IL-12p70, interferon-γ and TNF-α at the time of ES. For IL8 and procalcitonin, there was evidence that the absolute difference (or fold change) between engraftment and pre-conditioning or day 0 differed according to ES. In particular, procalcitonin increased from baseline (15.1 median fold increase in ES+ versus 2.31 median fold increase in ES-, P = 0.0006, median difference: 13.8, 95% confidence interval: 6.33, 65.6).

CONCLUSIONS

Our data provide one of the first prospective studies evaluating cytokines in pediatric allogeneic HSCT and suggest that elevated procalcitonin may serve as a biomarker for ES. Further studies to evaluate this finding are warranted.

Association between C-reactive protein levels in the first 1-3 days post-transplant and allogeneic immune reactions

AIM

The purpose of this study was to determine whether C-reactive protein (CRP) in the first 1-3 days post-transplant could predict allogeneic immune reactions, including engraftment syndrome or acute graft-versus-host disease (GVHD), in pediatric haploidentical stem cell transplantation.

PATIENTS & METHODS

The study population comprised 175 consecutive pediatric patients. Receiver operating characteristic analysis was performed to identify the cut-off CRP value.

RESULTS

The high-CRP group (≥20.1 mg/l) was associated with an increased occurrence of engraftment syndrome (hazard ratio [HR] = 2.046; p = 0.008), II-IV acute GVHD (HR = 2.203; p = 0.001) and severe GVHD (HR = 6.371; p = 0.004).

CONCLUSION

Our data suggest that higher CRP during the first 1-3 days post-transplant could be a predictor of allogeneic immune reactions.

Evaluation of engraftment syndrome in children following full-matched related donor hematopoietic stem cell transplantations

The term "ES" has been widely used for describing a clinical condition consisting of skin rash, fever, and weight gain that occur during neutrophil recovery period following HSCT. In this study, the incidence, clinical features, risk factors, and outcomes of ES were evaluated in 169 children following allogeneic HSCT from full-matched related donor according to the Spitzer criteria. Seventeen patients (10.1%) presented with clinical conditions suggesting ES. In both univariate and multivariate analysis underlying malignant disease and early release of monocytes to the PB, and in univariate analysis using only CsA for GVHD prophylaxis were found to be the significant risk factors for the development of ES. Patients with ES experienced significantly higher incidence of acute and chronic GVHD and propensity toward a higher rate of TRM. OS did not differ between the patient groups. Thirteen of 17 patients received steroid therapy, and all but one patient responded to therapy. Monitoring for early detection of ES and early intervention with steroid therapy is the key for recovery. The most crucial approach for this purpose mainly is to find out and use the most useful and feasible diagnostic criteria for routine medical practice.

Favorable outcome to glucocorticoid therapy for engraftment syndrome in pediatric autologous hematopoietic cell transplant

ES remains an important cause of morbidity and mortality in children undergoing auto-HCT. Glucocorticoid use in ES is an area of debate. We retrospectively analyzed single-institution experience from September 2000 through December 2012 to evaluate the use of glucocorticoids in auto-HCT patients. ES was defined by the occurrence of new onset of non-infectious fever plus diarrhea, rash, or pulmonary infiltrates 24-h before or within five days after neutrophil engraftment. Sixty-five pediatric patients (<21 yr) with different solid tumors underwent auto-HCTs in the study period. Fifteen patients (23%) fulfilled criteria for ES, of which 13 received methylprednisolone (2 mg/kg IV for 3-5 days). Clinical improvement occurred in all patients within 48 h without significant complications. In the non-ES group, 11 patients received glucocorticoid without significant complications as well. MEL-based regimens were found to be significant factor for ES (p < 0.05). Fever, edema, non-infectious diarrhea, and serum albumin concentration were statistically different between the two groups. Median hospital length of stay was higher in the ES group.

CONCLUSION

ES is a common complication in children after auto-HCT and short-course glucocorticoid therapy is an effective and well-tolerated treatment, even in those who did not completely fulfill diagnostic criteria.

Infusion-related febrile reaction after haploidentical stem cell transplantation in children is associated with higher rates of engraftment syndrome and acute graft-versus-host disease

The clinical significance and prognostic impact of IRFR in pediatric recipients of haploidentical SCT are not clearly understood. Therefore, we attempted to determine how IRFR affects clinical outcomes in children. Clinical data from 100 consecutive pediatric patients (60 boys and 40 girls; median age, 12 yr [range, 2-18 yr] after haploidentical SCT between January 2010 and December 2012 were collected retrospectively. IRFR was described as unexplained fever (>38 °C) within 24 h after the infusion of haploidentical PBSCs. Thirty-eight (38.0%) cases met the criteria for IRFR. ES was found in 24 (63.2%) of the 38 children with IRFR, with the median time of developing ES of +9 (7-16) days, while only 15 (25.4%) of the 59 children without IRFR were found with ES (p < 0.001). Similarly, the cumulative incidence rates of grade II-IV aGVHD were 50.0% in the IRFR group and 29.3% (p = 0.012) in the non-febrile group. Multivariate analysis identified IRFR as the risk factor for ES and aGVHD. In the haploidentical setting, IRFR is associated with the development of ES and aGVHD. We attempted to determine how IRFR affects clinical outcomes in children after haploidentical SCT. Thirty-eight children comprised the IRFR group, and 59 were in the control (non-IRFR) group. High incidence of ES was observed in children with the occurrence of IRFR. Similarly, the incidence of stage I-IV and II-IV aGVHD was significantly higher in the febrile group. Multivariate analysis showed IRFR to be the risk factor for ES and aGVHD.

Engraftment syndrome in hematopoietic stem cell transplantations

Hematopoietic stem cell transplantation (HSCT) is an increasingly common treatment option for malignant and nonmalignant diseases, but it has significant associated morbidity and mortality. Nurses caring for HSCT recipients must be aware of all potential complications, including engraftment syndrome (ES). Previous nursing literature has included little information on this syndrome, which often presents with noninfectious fever, skin rash, and pulmonary infiltrates, and ES may be fatal if left unidentified and treatment is not initiated promptly. Reports of the risk factors, incidence, clinical manifestations, diagnosis, treatment, and outcomes have much variation, likely from a lack of definite diagnostic criteria and inconsistency in the terminology associated with ES. The purpose of this article is to provide an overview of ES and the implications for nursing practice and research.

Acute renal endothelial injury during marrow recovery in a cohort of combined kidney and bone marrow allografts

An idiopathic capillary leak syndrome ('engraftment syndrome') often occurs in recipients of hematopoietic cells, manifested clinically by transient azotemia and sometimes fever and fluid retention. Here, we report the renal pathology in 10 recipients of combined bone marrow and kidney allografts. Nine developed graft dysfunction on day 10-16 and renal biopsies showed marked acute tubular injury, with interstitial edema, hemorrhage and capillary congestion, with little or no interstitial infiltrate (≤10%) and marked glomerular and peritubular capillary (PTC) endothelial injury and loss by electron microscopy. Two had transient arterial endothelial inflammation; and 2 had C4d deposition. The cells in capillaries were primarily CD68(+) MPO(+) mononuclear cells and CD3(+) CD8(+) T cells, the latter with a high proliferative index (Ki67(+) ). B cells (CD20(+) ) and CD4(+) T cells were not detectable, and NK cells were rare. XY FISH showed that CD45(+) cells in PTCs were of recipient origin. Optimal treatment remains to be defined; two recovered without additional therapy, six were treated with anti-rejection regimens. Except for one patient, who later developed thrombotic microangiopathy and one with acute humoral rejection, all fully recovered within 2-4 weeks. Graft endothelium is the primary target of this process, attributable to as yet obscure mechanisms, arising during leukocyte recovery.

Pre-engraftment syndrome in hematopoietic stem cell transplantation

The clinical findings of fever and skin rash with or without evidence of fluid retention, which mimic engraftment syndrome, have been observed during the pre-engraftment period in patients undergoing hematopoietic stem cell transplantation. In order to characterize this newly observed clinical syndrome called pre-engraftment syndrome (pES), we retrospectively analyzed the clinical records of 50 patients. Three out of 14 patients (23.1%) who underwent cord blood stem cell transplantation developed non-infectious fever, skin rash, and tachypnea 4-15 days prior to neutrophil engraftment. Two patients spontaneously recovered with fluid restriction and oxygen inhalation. One patient died of a complicated pulmonary hemorrhage in spite of aggressive supportive therapy and steroid treatment. Four out of 23 patients (17.4%) who underwent allogeneic bone marrow transplantation developed non-infectious fever and skin rash 4 to 5 days prior to neutrophil engraftment. All four of these patients recovered with only steroid treatment. These characteristic findings were not observed in patients who had undergone autologous peripheral blood stem cell transplantation. Interestingly, the speed of neutrophil engraftment was significantly faster for the patients suffering from pre-engraftment syndrome. The close observation and further pathophysiological research are required to better understand this syndrome.