ABSTRACT
In December 2019 a novel coronavirus (SARS-CoV-2) was identified in Wuhan, China, and became rapidly the worst pandemic in 100 years. Coronaviruses are respiratory viruses that can cause diseases ranging from mild to fatal lower respiratory tract infections. In a fraction of the affected patients, coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, can lead to acute respiratory distress syndrome (ARDS) and intensive care unit (ICU) admission, both associated with high mortality. To date, the existing evidence suggests a leading role of the immune system in the pathogenesis of severe COVID-19, including mechanisms associated with hyperinflammation, immune evasion, cytokine release syndrome, depletion of functional T cells, and ineffective humoral immunity. Here we discuss the current evidence regarding these findings.
Subject(s)
Humans , COVID-19/diagnosis , COVID-19/immunology , Respiratory Distress Syndrome, Newborn/physiopathology , C-Reactive Protein/analysis , Cytokines/analysis , Cytokine Release Syndrome , COVID-19/epidemiology , ImmunityABSTRACT
Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for children and adolescents with various malignant and non-malignant diseases. While human leukocyte antigen (HLA)-identical sibling donor is the preferred choice, matched unrelated volunteer donor is another realistic option for successful HSCT. Unfortunately, it is not always possible to find a HLA-matched donor for patients requiring HSCT, leading to a considerable number of deaths of patients without undergoing transplantation. Alternatively, allogeneic HSCT from haploidentical family members could provide donors for virtually all patients who need HSCT. Although the early attempts at allogeneic HSCT from haploidentical family donor (HFD) were disappointing, recent advances in the effective ex vivo depletion of T cells or unmanipulated in vivo regulation of T cells, better supportive care, and optimal conditioning regimens have significantly improved the outcomes of haploidentical HSCT. The ex vivo techniques used to remove T cells have evolved from the selection of CD34+ hematopoietic stem cell progenitors to the depletion of CD3+ cells, and more recently to the depletion of αβ+ T cells. The recent emerging evidence for ex vivo T cell-depleted haploidentical HSCT has provided additional therapeutic options for pediatric patients with diseases curable by HSCT but has not found a suitable related or unrelated donor. This review discusses recent advances in haploidentical HSCT, focusing on transplant using ex vivo T cell-depleted grafts. In addition, our experiences with this novel approach for the treatment of pediatric patients with malignant and non-malignant diseases are described.
Subject(s)
Adolescent , Child , Humans , Hematopoietic Stem Cell Transplantation , Hematopoietic Stem Cells , Leukocytes , Siblings , T-Lymphocytes , Tissue Donors , Transplants , Unrelated Donors , VolunteersABSTRACT
Objective To explore the efficacy of non-T cell depletion haploidentical hematopoietic stem-cell transplantation for T lymphoblastic lymphoma (T-LL). Methods 3 T-LL patients achieving complete remission received haploidentical bone marrow stem cell transplantation with granulocyte-colony-stimulating factor (G-CSF) mobilized bone marrow grafts from related donor without T-cell depletion. Two of them received a myeloablative conditioning regimen consisting of high-doses of cyclophosphamide and cytarabine with total body irradiation, whereas the other was preconditioned with busulfan, cyclophosphamide and cytarabine. All patients received strengthened phophylaxis regimen including rabbit anti-thymocyte globulin against acute graft-versus-host disease. Results All patients had rapid hematopoietic engraftment with the median time for neutrophil and platelet recovery being 12 days and 13 days, respectively. They are still alive without relapse at a median follow-up of 24 months (range: 9-75 months). Conclusion Treatment related toxicity can be acceptable in non-T cell depletion haploidenfical hematopoietic stem-cell transplantation for T-LL and the patients may achieve long term survival.
ABSTRACT
The development of immunosuprressants has had a significant influence on inhibition of acute allograft rejection. However, long-term graft survival has not been achieved by immunosuppressants, probably because of their nonspecific suppression of T cell activity and nonimmune side effects. The ideal way to overcome the limitations of current immunosuppressants is to induce allograft-specific immune tolerance. Transplant immunologists are exerting their efforts in achieving transplantation tolerance using four different approaches; costimulatory blockade, mixed hematopoietic chimerism, T cell depletion, and regulation by regulatory T cells. It is expected that transplantation tolerance will soon be established as a standard immunosuppressive regimen with little side effects in preventing and reversing allograft rejection.