Graft-versus-leukaemia activity associated with cytomegalovirus seropositive bone marrow donors but separated from graft-versus-host disease in allograft recipients with AML

To elucidate whether a relationship existed between bone marrow donor cytomegalovirus (CMV) immune status and the probability of staying in remission after transplantation, a retrospective multicentre analysis was performed in 69 patients who received allogeneic bone marrow transplantation during relapse or second remission of AML, or second remission of ALL. None of 12 AML patients with CMV seropositive donors had posttransplant relapse, in contrast to 7 of 10 AML patients with seronegative donors. Kaplan-Meier estimates of the 2-yr probability of staying in remission for the two groups were 100% and 0%, respectively (p less than 0.0005). This effect was independent of disease stage, donor and recipient age, recipient pretransplant CMV immune status and the occurrence of posttransplant CMV infection in recipients, and was not mediated through an increased occurrence of overt graft-versus-host disease (GvHD) in recipients with CMV seropositive donors. The increased probability of staying in remission was associated with an increased probability of 3-yr disease-free survival (p less than 0.01). No similar effect was observed in patients with ALL. This study may suggest an allograft-versus-leukaemia effect in AML, associated with CMV seropositive donors, which seems separate from GvHD and independent of the occurrence of posttransplant CMV infection.     

Identification of both myeloid CD11c+ and lymphoid CD11c− dendritic cell subsets in cord blood

Dendritic cells (DCs) are the most potent antigen-presenting cells described to date. In human peripheral blood, both myeloid and lymphoid subsets of DCs have been identified. In contrast, cord blood (CB) DCs have recently been described as being exclusively of the immature CD11c- lymphoid DC subset. Using an alternative method of enrichment, based on a negative selection system, both lymphoid (HLA-DR+ CD123+++ CD11c- CD33-) and myeloid (HLA-DR++ CD123+ CD11c+ CD33+) DCs were identified in CB. Although the majority of CB DCs showed a lymphoid phenotype, a significant number of CD11c+ myeloid DCs (25.6% +/- 14.5%, n = 13) were also present. Other markers, such as CD80 and CD83, were negative in both subsets. Analyses of the allostimulatory capacity of both subsets showed that freshly isolated CB lymphoid DCs failed to induce a potent allostimulation of naive CB T cells. These features are therefore consistent with previous work reporting an immature phenotype for lymphoid DCs in adult blood. The significance of the inverted CD11c+/CD11c- ratio observed in CB DCs (1:3) with respect to adult blood DCs (3:1) remains to be explained.     

Non-infectious causes of elevated procalcitonin and C-reactive protein serum levels in pediatric patients with hematologic and oncologic disorders

BACKGROUND: Procalcitonin (PCT) is considered a sensitive and specific diagnostic and prognostic marker of systemic bacterial infection, but its value is questionable in certain clinical conditions, particularly in hemato-oncological patients. MATERIALS AND METHODS: We analyzed PCT and C-reactive protein (CRP) levels in 56 patients of a pediatric hematology-oncology unit during 110 consecutive non-infectious febrile episodes related to administration of T-cell antibodies (group A; n = 22), alemtuzumab (monoclonal CD52 antibody, CAMPATH-1H/group B; n = 8), interleukin-2 (IL-2/group C; n = 41), prophylactic donor granulocyte transfusions (group D; n = 9), or to acute graft-versus-host disease (aGvHD/group E; n = 10) and compared the results with 20 episodes of Gram-negative sepsis (group F). MAIN RESULTS: In the majority of the non-infectious episodes PCT and CRP increased to serum levels statistically indistinguishable from Gram-negative sepsis. Median peak levels of PCT (normal < 0.5 ng/ml)/CRP (normal < 8 mg/l) for groups A-F were 4.34/59.0 (A), 10.14/93.5 (B), 1.11/175.0 (C), 1.43/164 (D), 0.96/34.0 (E), and 8.14 ng/ml /126.0 mg/l (F). Highest single levels were observed in groups A and F. CONCLUSIONS: PCT and CRP are of limited value as diagnostic markers of sepsis during T-cell-directed immunomodulatory treatment, granulocyte support, or acute GvHD.     

Regulatory T cells for tolerance

Regulatory T cells (Tregs) are critical mediators of immune homeostasis and hold significant promise in the quest for transplantation tolerance. Progress has now reached a critical threshold as techniques for production of clinical therapies are optimised and Phase I/II clinical trials are in full swing. Initial safety and efficacy data are being reported, with trials assessing a number of different strategies for the introduction of Treg therapy. It is now more crucial than ever to elucidate further the function and behaviour of Tregs in vivo and ensure safe delivery. This review will discuss the current state of the art and future directions in Treg therapy.     

Different strategies of mixed chimerism induction may determine stem/progenitor cell populations in recipient mice

Mixed chimerism has been suggested to induce tolerance to transplanted alloantigens. As the precise influence of mixed chimerism induction on the host organism has still not been fully elucidated, the aim of the present study was to explore this phenomenon in relation to the stem cell compartment.The experiment was performed on B6.SJL-Ptprc^aPep3^b mice. Mixed chimerism induction protocols involved 3 Gy TBI (Day − 1 of the experiment), injection of 20-30 × 10⁶ Balb C bone marrow cells (Day 0), and administration of blocking antibodies against CD40L (Day 0 and Day 4), anti-CD8 (Day − 2) with/without anti-NK1.1 (Day − 3). Selected groups of mice were also treated with cyclophosphamid (175 mg/kg) on Day 2. The presence of mixed chimerism was assessed in peripheral blood, bone marrow, and spleen, as well as in various subpopulations of leukocytes (CD4⁺, CD8⁺, CD45/B220⁺, Gr-1⁺, lin⁻/Sca-1⁺/c-kit⁻, lin⁻/Sca-1⁺/c-kit⁺, lin⁻/Sca-1⁻/c-kit⁺). Furthermore, the percentage of stem/progenitor cells (lin⁻/Sca-1⁺/c-kit⁻, lin⁻/Sca-1⁺/c-kit⁺, lin⁻/Sca-1⁻/c-kit⁺, VSEL, HSC) was analysed for the first time in bone marrow and peripheral blood of chimeric mice.The range of mixed chimerism differed significantly among various cell populations: it was lowest in CD8-positive cells and lin⁻/Sca-1⁺/c-kit⁻ cells, and highest in granulocytes. The induction of mixed chimerism revealed a significant impact on the stem/progenitor cell frequency in recipient mice, providing potential therapeutic insights into the long-term immunologic tolerance observed in chimeric mice. Collectively, these findings contribute to further optimization of mixed chimerism induction protocols and might help in the introduction of this phenomenon into clinical practice.     

Chlorhexidine gluconate–impregnated central-line dressings and necrosis in complicated skin disorder patients

Although chlorhexidine gluconate (CHG) disks have been shown to help reduce the incidence of central line–associated blood stream infections, their use can result in local skin necrosis. The effects of CHG disks on patients with complex skin pathology have not been studied. We report 6 cases of dermal necrosis associated with Biopatch (Ethicon Inc, Somerville, NJ) CHG disks in adults with complex skin pathology including those with Stevens-Johnson syndrome, toxic epidermal necrolysis syndrome, graft-versus-host disease, burns, and anasarca. All patients had a CHG disk placed at a central venous catheter insertion site. Age range was from 21 to 84 years. Discovery of the reaction ranged from 4 to 14 days after disk placement. Resultant skin erosions required 2 to 10 weeks to reepithelialize. Complicated skin disorder patients represent a rare subset of the critically ill who appear prone to CHG disk necrosis. Continuous contact of CHG under occlusive dressings is speculated to predispose Stevens-Johnson syndrome, toxic epidermal necrolysis syndrome, graft-versus-host disease, and burn patients to local chemical injury secondary to loss of the epithelial tissue barrier, decreased cohesion of the epidermal-dermal junction, and increased tissue permeability. In these patients, the risk of placing the CHG disk may present more risk than using alternative antimicrobial dressings.     

Association between leukocyte infiltration and development of glomerulosclerosis in experimental lupus nephritis

Mice with chronic graft-versus-host disease (GvHD) induced by injection of DBA/2 lymphocytes into (DBA/2×C57BL/10) F1 hybrids (DBA/2 GvHD) develop a lupus-like glomerulonephritis with global glomerulosclerosis 12 weeks after induction of the disease. In two other strain combinations with similar H-2 incompatibilities [BALB/c into BALB/c×BL10 (BALB/c GvHD) and BALB.D2 into BALB.D2×BL10 (BALB.D2 GvHD)], GvHD induction leads to lupus nephritis without global glomerulosclerosis. This study investigated the identity of kidney-infiltrating leukocytes and their involvement in the development of glomerulosclerosis in these three strain combinations. In mice with DBA/2 GvHD, a significant increase in glomerular CD11a-positive cells was found 4 weeks after disease induction. Mice with BALB/c or BALB.D2 GvHD did not show an increase in glomerular CD11a-positive cells at any time point. In the interstitium, CD11a-positive cells were observed 4 weeks after disease induction only in mice with DBA/2 GvHD. In mice with BALB.D2 GvHD, no increase was found in interstitial CD11a-positive cells. In mice with BALB/c GvHD, interstitial CD11a-positive cells were found from week 4 onward. Further immunohistochemical analysis of the glomerular CD11a-positive cells in mice with DBA/2 GvHD showed that these cells were neither polymorphonuclear leukocytes (PMN), nor CD3-positive (T cells), B220-positive (B cells), or F4/80-positive (macrophages). They were all CD45-positive (leukocytes) and MHC class II-positive. In conclusion, we have shown in this model of chronic lupus nephritis that glomerular influx of as yet unidentified CD11a-positive leukocytes is associated with the development of glomerulosclerosis. © 1998 John Wiley & Sons, Ltd.     

Primary vaccination in adult patients after allogeneic hematopoietic stem cell transplantation – A single center retrospective efficacy analysis

Allogeneic hematopoietic stem cell transplantation (alloHSCT) results in a loss of humoral immunity and subsequent risk for severe infections. Thus, re-vaccination is required but may fail due to incomplete immune reconstitution. We retrospectively analyzed predictors of immune response to primary vaccination applied according to the EBMT (European Blood and Marrow Transplantation Group) recommendations. Serologic response to vaccination against diphtheria (D), tetanus (T), Bordetella pertussis (aP) and Haemophilus influenzae (Hib) (administrated as combined DTaP-Hib-IPV vaccination) was studied in 84 alloHSCT patients transplanted between 2008 and 2015 (age at alloHSCT: 18.6–70.6 years). All patients with a relapse-free survival of ≥9 months, at least 3 consecutive vaccinations and absence of intravenous immunoglobulin administration within 3 months before and after vaccination met the primary inclusion criteria. Additionally, immunological response to a pneumococcal conjugate vaccine was analyzed in a subgroup of 67 patients. Patients’ characteristics at the time of first vaccination were recorded. Responses were measured as vaccine-specific antibody titers. Regarding DTaP-Hib-IPV vaccination, 89.3% (n = 75) of all patients achieved protective titers to at least 3 of the 4 vaccine components and were thus considered responders. 10.7% (n = 9) of the patients were classified as non-responders with positive immune response to less than 3 components. Highest response was observed for Hib (97.4%), tetanus (95.2%) and pneumococcal vaccination (83.6%) while only 68.3% responded to vaccination against Bordetella pertussis. Significant risk factors for failure of vaccination response included low B cell counts (p < 0.001; cut-off: 0.05 B cells/nl) and low IgG levels (p = 0.026; mean IgG of responders 816 mg/dl vs. 475 mg/dl of non-responders). Further, a trend was observed that prior cGvHD impairs vaccination response as 88.9% of the non-responders but only 54.7% of the responders had prior cGvHD (p = 0.073). The results demonstrate, that the currently proposed vaccination strategy leads to seroprotection in the majority of alloHSCT patients.     

In vivo depletion of NKR-P1 positive cells in the recipient prior to small bowel transplantation enhances graft-versus-host disease (GvHD) in the rat

Abstract  Recent evidence for major histocompatibility complex (MHC) class I antigen-directed recognition mechanisms of natural killer cells (NKs) have revived interests in investigating non-adaptive immune responses in the framework of solid organ transplantation. A semi-allogeneic rat model of heterotopic small bowel transplantation (HSBTx) from male DA parental to male F1 hybrid rats (DA X LEW) was established to investigate the role of host NKs to attenuate graft-versus-host (GvH)-mediated immu-nosuppression and tissue injury. By use of anti-NKR-P1 monoclonal antibody (mAb) 3.2.3, host NKs were depleted effectively in vivo after triple intraperitoneal injection prior to HSBTx. In contrast to non-depleted animals, an initial lack of NK activity in F1 hosts significantly decreased the mean survival ( P < 0.01) and substantially enhanced graft-versus-host disease (GvHD)-related damage to lymphoid and non-lym-phoid target organs. These findings emphasize the important immuno-regulatory role of host NKs during the early onset of GvHD.