Major Histocompatibility Complex Class II Deficiency due to a Novel Mutation in RFXANK in a Child of Mexican Descent.

MHC Class II deficiency (also known as bare lymphocyte syndrome type II) is a rare primary immunodeficiency disorder inherited in an autosomal recessive fashion resulting from the absence of MHC class II molecules on the surface of immune cells. Here, we report a now 18-month-old male born to consanguineous Mexican-American parents who presented at four months with pneumocystis pneumonia, and was subsequently found to have a novel homozygous mutation in RFXANK leading to MHC Class II deficiency. He was successfully treated via hematopoietic stem cell transplantation from his matched sibling

Characteristic immune abnormalities in hemophagocytic lymphohistiocytosis

Purpose: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening syndrome characterized by fever, hepatosplenomegaly, pancytopenia, and infiltration of vital organs by non-Langerhans histiocytes and is rapidly fatal without early diagnosis and institution of therapy. Immune dysregulation is thought to be responsible for the disease. Patients and Methods: Extensive immune evaluation was performed on 13 consecutive patients diagnosed with HLH over a 4-year period to characterize existing immunologic abnormalities in order to improve early diagnosis. Evaluation included quantitative immunoglobulins, immunophenotyping, mitogen-induced lymphoproliferation, natural killer (NK) cell function, and cytotoxic T cell lymphocytolysis (CTL). Results: Immunoglobulin levels showed no consistent abnormality. Immunophenotyping showed an absolute decrease in number of B cells but normal numbers and proportional distribution of T cell subsets and NK cells. Most patients demonstrated decreased proliferative responses to mitogens (10/13) and severely decreased to absent T cell cytotoxicity (11/12) and NK cytotoxic function (13/13). Conclusions: Our results show that while humoral immunity is essentially intact, cellular immune function is significantly impaired in the vast majority of patients with HLH. The coincident finding of profoundly decreased T cell cytotoxicity along with absent NK cytotoxicity suggests that patients with active HLH may have global cytotoxic dysfunction. Since the majority of our patients were studied prior to starting therapy, we feel that these findings reflect the pathophysiologic process and are not therapy related. Unclear from the present work is whether these findings represent primary or secondary dysfunction. We conclude from these studies that profoundly decreased CTL function and absence of NK cell function are characteristic immunologic features of HLH and may serve as additional laboratory data, in conjunction with currently proposed diagnostic guidelines, to support a diagnosis of HLH

Epstein-Barr and other herpesvirus infections in patients with early onset type 1 diabetes treated with daclizumab and mycophenolate mofetil

Background. We assessed the morbidity of herpesviruses in patients with type 1 diabetes mellitus (T1D) enrolled in immunosuppressive treatment studies. Methods. Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus (HSV), and varicella zoster virus (VZV) infections were monitored in 126 participants of a randomized, double-blind, placebo-controlled study of daclizumab (DZB) and mycophenolate mofetil (MMF) including DZB(+)MMF(+), DZB(−)MMF(+), DZB(+)MMF(−), and DZB(−)MMF(−). During the 2-year follow-up, herpesviral infections were monitored clinically, by serology and blood DNA polymerase chain reaction. Results. Among 57 baseline EBV-seronegative participants, 9 developed EBV primary infections, including 2 with infectious mononucleosis syndrome. There were no appreciable differences in the course of the primary EBV infections across treatment groups. Among 69 baseline EBV-seropositive participants, 22 had virologic reactivations, including 1 symptomatic DZB(−)MMF(+) subject. Compared with 7 DZB(–)MMF(–) EBV reactivators, the 9 DZB(+)MMF(+) reactivators tended to have more prolonged viremia (11.4 vs 4.4 months; P = .06) and higher cumulative viral burden (14.2 vs 12.5 log EBV copies/mL; P = .06). Four of 85 baseline CMV-seronegative subjects developed asymptomatic primary CMV infections. There were no CMV reactivations. Of 30 baseline HSV-seropositive subjects, 8 developed ≥1 episode of herpes labialis; 1 subject had a primary HSV infection; and 1 subject without baseline serology information had a new diagnosis of genital HSV. There were no significant differences in the incidence of HSV recurrences across treatment groups. Of 100 baseline VZV-seropositive subjects, 1 DZB(–)MMF(–) subject developed herpes zoster and 1 DZB(−)MMF(+) subject had Bell's palsy possibly related to VZV. Conclusions. The use of DZB alone or in combination with MMF was not associated with increased morbidity due to herpesviruses. Clinical Trials Registration. NCT00100178

Hematopoietic Cell Transplantation Using Reduced-Intensity Conditioning Is Successful in Children with Hematologic Cytopenias of Genetic Origin

Genetically derived hematologic cytopenias are a rare heterogeneous group of disorders. Allogeneic hematopoietic cell transplantation (HCT) is curative but offset by organ toxicities from the preparative regimen, graft rejection, graft-versus-host disease (GVHD), or mortality. Because of these possibilities, consideration of HCT can be delayed, especially in the unrelated donor setting. We report a prospective multicenter trial of reduced-intensity conditioning (RIC) with alemtuzumab, fludarabine, and melphalan and HCT in 11 children with marrow failure of genetic origin (excluding Fanconi anemia) using the best available donor source (82% from unrelated donors). The median age at transplantation was 23 months (range, 2 months to 14 years). The median times to neutrophil (>500 × 106/L) and platelet (>50 × 109/L) engraftment were 13 (range, 12 to 24) and 30 (range, 7 to 55) days, respectively. The day +100 probability of grade II to IV acute GVHD and the 1-year probability of limited and extensive GVHD were 9% and 27%, respectively. The probability of 5-year overall and event-free survival was 82%; 9 patients were alive with normal blood counts at last follow-up and all were successfully off systemic immunosuppression. In patients with genetically derived severe hematologic cytopenias, allogeneic HCT with this RIC regimen was successful in achieving a cure. This experience supports consideration of HCT early in such patients even in the absence of suitable related donors

Screening and Monitoring for Infectious Complications When Immunosuppressive Agents Are Studied in the Treatment of Autoimmune Disorders.

Significant progress has been made in the development, investigation, and clinical application of immunosuppressive agents to treat a variety of autoimmune disorders. The expansion of clinical applications of these new agents requires the performance of large multicenter clinical trials. These large clinical trials are particularly important as one considers these agents for the treatment of type 1 diabetes, which although autoimmune in its pathogenesis, is not classically treated as an autoimmune disorder. Although these agents hold promise for amelioration or cure of this disease, they have the potential to facilitate infectious complications. There are limited data regarding the prospective assessment of infectious risks with these agents in trials of this nature. Pediatric subjects may be at greater risk due to the higher likelihood of primary infection. A subgroup of experts associated with TrialNet (a National Institutes of Health [NIH]-funded Type 1 diabetes mellitus research network) with expertise in infectious diseases, immunology, and diagnostics developed an approach for screening and monitoring of immunosuppression-associated infections for prospective use in clinical trials. The goals of these recommendations are to provide a structured approach to monitor for infections, to identify specific laboratory testing and surveillance methods, and to consider therapies for treatment of these potential complications. Prospective evaluations of these infectious risks allow for greater scientific rigor in the evaluation of risk, which must be balanced with the potential benefits of these therapies. Our experience supports an important role for investigators with expertise in infections in immunocompromised individuals in protocol development of immunosuppressive trials in type 1diabetes and potentially other autoimmune diseases