Allogeneic hematopoietic stem cell transplantation in leukocyte adhesion deficiency type 1: a single center experience

Functional neutrophil disorders: Chronic granulomatous disease and beyond

Since their description by Metchnikoff in 1905, phagocytes have been increasingly recognized to be the entities that traffic to sites of infection and inflammation, engulf and kill infecting organisms, and clear out apoptotic debris all the while making antigens available and accessible to the lymphoid organs for future use. Therefore, phagocytes provide the gateway and the first check in host protection and immune response. Disorders in killing and chemotaxis lead not only to infection susceptibility, but also to autoimmunity. We aim to describe chronic granulomatous disease and the leukocyte adhesion deficiencies as well as myeloperoxidase deficiency and G6PD deficiency as paradigms of critical pathways.

Case Report: A Case of Leukocyte Adhesion Deficiency, Type III Presenting With Impaired Platelet Function, Lymphocytosis and Granulocytosis

Fermitin family homolog 3 (FERMT3), alternatively kindlin-3 (KIND3), is an integrin binding protein (of 667 residues) encoded by the FERMT3 gene. The molecule is essential for activating integrin α_IIbβ₃ (the fibrinogen receptor) on platelets and for the integrin-mediated hematopoietic cell (including platelets, T lymphocytes, B lymphocytes, and granulocytes) adhesion. Its defects are associated with impaired primary hemostasis, described as "Glanzmann's thrombasthenia (MIM#273800)-like bleeding problem." The defects are also associated with infections, designated as "LAD1 (leukocyte adhesion deficiency, type I; MIM#116920)-like immune deficiency." The entity that joins the impaired primary hemostasis with the leukocyte malfunction has been termed "leukocyte adhesion deficiency, type III" (LAD3, autosomal recessive, MIM#612840), representing a defective activation of the integrins β₁, β₂, and β3 on leukocytes and platelets. Here, we report a male toddler with novel compound heterozygous variants, NM_178443.2(FERMT3):c.1800G>A, p.Trp600^* (a non-sense variant) and NM_178443.2(FERMT3):c.2001del p.^*668Glufs^*106 (a non-stop variant). His umbilical cord separated at about 3 weeks of age. A skin rash (mainly petechiae and purpura) and recurrent episodes of severe epistaxis required blood transfusions in early infancy. His hemostatic work-up was remarkable for a normal platelet count, but abnormal platelet function screen with markedly prolonged collagen-epinephrine and collagen-ADP closure times. The impaired platelet function was associated with reduced platelet aggregation with all agonists. The expression of platelet receptors was normal. Other remarkable findings were persistent lymphocytosis and granulocytosis, representing defects in diapedesis due to the integrin dysfunction. The natural history of his condition, structure and sequence analysis of the variations, and comparison with other LAD3 cases reported in the literature are presented.

Successful reconstitution of leukocyte adhesion defect after umbilical cord blood stem cell transplant

Leukocyte adhesion deficiencies (LADs) are a type of primary immunodeficiencies characterized by delayed detachment of the umbilical cord, impaired wound healing, leukocytosis, and recurrent infections. The disease is caused by genetic defects affecting different steps in the process of leukocyte adhesion cascade such as rolling, integrin activation, and adhesion of leukocytes, resulting in the impairment of leukocyte trafficking. Till date, three types of LAD have been documented: type I, II and III. Type I LAD is caused by congenital defect in the β2 integrin receptor complex CD11/CD18 on the cell surface of leukocytes, which results in impaired leukocytes connection to endothelial cells and migration. Type II LAD is caused by defect in the fucose metabolism resulting in the absence of fucosylated selectin ligands on neutrophils and impaired rolling phase of the leukocyte adhesion cascade. Type III LAD is caused by mutations in the kindlin-3 gene resulting in defective integrin activation. In this article, we present a review of literature for type I LAD, and successful treatment of patient using umbilical cord blood stem cell transplantation.

Successful umbilical cord blood transplantation in children with leukocyte adhesion deficiency type I

BACKGROUND

This study aims to investigate the efficacy and safety of umbilical cord blood transplantation (UCBT) without serotherapy for treating children with leukocyte adhesion deficiency type I (LAD-I).

METHODS

Clinical characteristics and data of five children with LAD-I who underwent UCBT at our hospital between September 2016 and September 2018 were retrospectively analyzed.

RESULTS

Five (two boys and three girls) patients with LAD-I were included. The median age at UCBT was 9 months (range, 8 to 32 months). The same myeloablative conditioning regimen was administered for each patient and included busulfan, fludarabine, and cyclophosphamide. HLA matching of patients and umbilical cord blood was 8/10 to 10/10. The median dose of total nucleated cells (TNC) infused was 10.2×10⁷/kg (range, 4.5×10⁷ to 20.6×10⁷/kg) and the median dose of CD34+ cells was 3.2×10⁵/kg (range, 1.9×10⁵ to 5.7×10⁵/kg). The median time of neutrophil engraftment was 20 days (range, 13 to 28 days). The median time of platelet engraftment was 36 days (range, 32 to 56 days). All patients received complete donor chimerism (CDC). Four of the five patients developed grade II-IV acute graft-versus-host disease (GvHD). The median follow-up time after transplantation was 19 months (range, 8 to 38 months). Four of the patients survived and achieved complete clinical remission. The other patient died of bronchiolitis obliterans 8 months after UCBT.

CONCLUSIONS

UCBT is an effective treatment method for LAD-I patients. Also, severe LAD-I patients should undergo stem cell transplantation as early as possible.

Update on Advances in Hematopoietic Cell Transplantation for Primary Immunodeficiency Disorders

Hematopoietic stem cell transplantation (HSCT) in patients with primary immunodeficiency disorders (PIDDs) is being increasingly used as a curative option. Understanding the critical components, such as disease's nature and activity and pre-HSCT and post-HSCT patient care is key to a successful outcome. HSCT should be tailored to the underlying PIDD, as different PIDDs, such as severe combined immune deficiency, Treg dysfunction, and phagocytic disorders, have different transplant approaches. Therefore, successful HSCT in patients with PIDDs requires teamwork between immunologists and transplant physicians. In this article, the authors elaborate on various aspects of PIDD-HSCT and highlight recent advances.

Allogeneic Hematopoietic Stem Cell Transplantation for Leukocyte Adhesion Deficiency

The clinical outcome of allogeneic hematopoietic stem cell transplantation (HSCT) was retrospectively analyzed in 6 patients with leukocyte adhesion deficiency. Of 3 patients transplanted with myeloablative conditioning, 2 patients had complete chimerism and 1 patient had mixed chimerism. By contrast, all 3 patients transplanted with reduced-intensity conditioning (RIC) had mixed chimerism, one of whom progressed to secondary graft failure. All patients with low-level mixed chimerism and secondary graft failure were rescued by donor lymphocyte infusion or a second HSCT. RIC-HSCT is feasible for leukocyte adhesion deficiency, although further refinement/modification of conditioning is required to achieve higher donor chimerism levels.

Primary Immunodeficiency Diseases in Highly Consanguineous Populations from Middle East and North Africa: Epidemiology, Diagnosis, and Care

Middle East and North Africa region (MENA)¹ populations are of different ethnic origins. Consanguineous marriages are common practice with an overall incidence ranging between 20 and 50%. Primary immunodeficiency diseases (PIDs) are a group of heterogeneous genetic disorders caused by defects in the immune system that predisposes patients to recurrent infections, autoimmune diseases, and malignancies. PIDs are more common in areas with high rates of consanguineous marriage since most have an autosomal recessive mode of inheritance. Studies of PIDs in the region had contributed into the discovery and the understanding of several novel immunodeficiency disorders. Few MENA countries have established national registries that helped in estimating the prevalence and defining common PID phenotypes. Available reports from those registries suggest a predominance of combined immunodeficiency disorders in comparison to antibody deficiencies seen in other populations. Access to a comprehensive clinical immunology management services is limited in most MENA countries. Few countries had established advanced clinical immunology service, capable to provide extensive genetic testing and stem cell transplantation for various immunodeficiency disorders. Newborn screening for PIDs is an essential need in this population considering the high incidence of illness and can be implemented and incorporated into existing newborn screening programs in some MENA countries. Increased awareness, subspecialty training in clinical immunology, and establishing collaborating research centers are necessary to improve patient care. In this review, we highlight some of the available epidemiological data, challenges in establishing diagnosis, and available therapy for PID patients in the region.

Lentiviral Vector-Mediated Correction of a Mouse Model of Leukocyte Adhesion Deficiency Type I

Leukocyte adhesion deficiency type I (LAD-I) is a primary immunodeficiency caused by mutations in the ITGB2 gene and is characterized by recurrent and life-threatening bacterial infections. These mutations lead to defective or absent expression of β₂ integrins on the leukocyte surface, compromising adhesion and extravasation at sites of infection. Three different lentiviral vectors (LVs) conferring ubiquitous or preferential expression of CD18 in myeloid cells were constructed and tested in human and mouse LAD-I cells. All three hCD18-LVs restored CD18 and CD11a membrane expression in LAD-I patient-derived lymphoblastoid cells. Corrected cells recovered the ability to aggregate and bind to sICAM-1 after stimulation. All vectors induced stable hCD18 expression in hematopoietic cells from mice with a hypomorphic Itgb2 mutation (CD18^HYP), both in vitro and in vivo after transplantation of corrected cells into primary and secondary CD18^HYP recipients. hCD18⁺ hematopoietic cells from transplanted CD18^HYP mice also showed restoration of mCD11a surface co-expression. The analysis of in vivo neutrophil migration in CD18^HYP mice subjected to two different inflammation models demonstrated that the LV-mediated gene therapy completely restored neutrophil extravasation in response to inflammatory stimuli. Finally, these vectors were able to correct the phenotype of human myeloid cells derived from CD34⁺ progenitors defective in ITGB2 expression. These results support for the first time the use of hCD18-LVs for the treatment of LAD-I patients in clinical trials.

Practice parameter for the diagnosis and management of primary immunodeficiency

The American Academy of Allergy, Asthma & Immunology (AAAAI) and the American College of Allergy, Asthma & Immunology (ACAAI) have jointly accepted responsibility for establishing the "Practice parameter for the diagnosis and management of primary immunodeficiency." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.