Volker Schuster

The syndrome of hemophagocytic lymphohistiocytosis in primary immunodeficiencies: implications for differential diagnosis and pathogenesis

Hemophagocytic lymphohistiocytosis is a hyperinflammatory syndrome defined by clinical and laboratory criteria. Current criteria were created to identify patients with familial hemophagocytic lmyphohistiocytosis in immediate need of immunosuppressive therapy. However, these criteria also identify patients with infection-associated hemophagocytic inflammatory states lacking genetic defects typically predisposing to hemophagocytic lymphohistiocytosis. These patients include those with primary immunodeficiencies, in whom the pathogenesis of the inflammatory syndrome may be distinctive and aggressive immunosuppression is contraindicated. To better characterize hemophagocytic inflammation associated with immunodeficiencies, we combined an international survey with a literature search and identified 63 patients with primary immunodeficiencies other than cytotoxicity defects or X-linked lymphoproliferative disorders, presenting with conditions fulfilling current criteria for hemophagocytic lymphohistiocytosis. Twelve patients had severe combined immunodeficiency with <100/μL T cells, 18 had partial T-cell deficiencies; episodes of hemophagocytic lymphohistiocytosis were mostly associated with viral infections. Twenty-two patients had chronic granulomatous disease with hemophagocytic episodes mainly associated with bacterial infections. Compared to patients with cytotoxicity defects, patients with T-cell deficiencies had lower levels of soluble CD25 and higher ferritin concentrations. Other criteria for hemophagocytoc lymphohistiocytosis were not discriminative. Thus: (i) a hemophagocytic inflammatory syndrome fulfilling criteria for hemophagocytic lymphohistiocytosis can be the initial manifestation of primary immunodeficiencies; (ii) this syndrome can develop despite severe deficiency of T and NK cells, implying that the pathophysiology is distinct and not appropriately described as “lympho”-histiocytosis in these patients; and (iii) current criteria for hemophagocytoc lymphohistiocytosis are insufficient to differentiate hemophagocytic inflammatory syndromes with different pathogeneses. This is important because of implications for therapy, in particular for protocols targeting T cells.

A combined measles, mumps, rubella and varicella vaccine (Priorix-Tetra™): Immunogenicity and safety profile

Priorix-Tetra (GlaxoSmithKline Biologicals) is a combined measles, mumps, rubella and varicella (MMRV) vaccine. Eight studies involving more than 3000 children were reviewed. Compared with co-administration of MMR (Priorix) and varicella (Varilrix) vaccines, the MMRV vaccine showed: similar immunogenicity, with immunity shown up to 3 years post-vaccination; a higher rate of fever after the first dose; a slight increase in mild local reactions after the second dose. This MMRV vaccine can be used either as a two-dose vaccine or as a second dose in children primed with separate MMR and/or varicella vaccines, offering a convenient way to introduce varicella vaccination into routine vaccination programmes.

Clinical and immunological overlap between autoimmune lymphoproliferative syndrome and common variable immunodeficiency

Autoimmune lymphoproliferative syndrome (ALPS) is mainly caused by defects in the CD95 pathway. Raised CD3+TCRαβ+CD4-CD8- double negative T cells and impaired T cell apoptosis are hallmarks of the disease. In contrast, the B cell compartment has been less well studied. We found an altered distribution of B cell subsets with raised transitional B cells and reduced marginal zone B cells, switched memory B cells and plasma blasts in most of 22 analyzed ALPS patients. Moreover, 5 out of 66 ALPS patients presented with low IgG and susceptibility to infection revealing a significant overlap between ALPS and common variable immunodeficiency (CVID). In patients presenting with lymphoproliferation, cytopenia, hypogammaglobulinemia and impaired B cell differentiation, serum biomarkers were helpful in addition to apoptosis tests for the identification of ALPS patients. Our observations may indicate a role for apoptosis defects in some diseases currently classified as CVID.

Ligneous conjunctivitis in a girl with severe type I plasminogen deficiency

Abstractu2002Background: Ligneous conjunctivitis is a rare form of chronic recurrent pseudomembranous disease and may be associated with systemic membranous pathological changes. Recently ligneous conjunctivitis has been linked to severe type I plasminogen deficiency. We report on a patient with plasminogen deficiency and severe bilateral ligneous conjunctivitis. A new treatment approach and its outcome in this patient are described. Case report:We present the case of a 9-month-old Turkish girl with massive swelling of the eyelids and hard white pseudomembranes on both lids. The conjunctival smear was positive for Streptococcus pneumoniae. The clinical diagnosis was: ligneous conjunctivitis with superinfection. Histological investigation showed fibrin as major component of the pseudomembranes. The coagulation analyses revealed decreased plasminogen activity (<5%; normal 80–120%) and decreased plasminogen antigen (<0.4 mg/dl; normal 6–25 mg/dl). The failure of surgical therapy led to the attempt at treatment with intravenous lys-plasminogen. A significant improvement of the ocular symptoms occurred; stabilization with no recurrent pseudomembranes could be achieved for 6 months after treatment. Discussion: The initial amelioration of symptoms in our patient after systemic replacement therapy confirms the etiological importance of plasminogen deficiency in the development of ligneous conjunctivitis. Curative treatment of ligneous conjunctivitis is still not available. However, intravenous application of plasminogen offers new possibilities in therapy, although long-term treatment seems necessary.

A missense mutation in the ZFHX1B gene associated with an atypical Mowat-Wilson syndrome phenotype.

Mowat–Wilson syndrome (MWS) is a rare mental retardation—multiple congenital anomalies syndrome associated with typical facial dysmorphism. Patients can show a variety of other anomalies like short stature, microcephaly, Hirschsprung disease, malformations of the brain, seizures, congenital heart defects and urogenital anomalies. Mutations leading to haploinsufficiency of the ZFHX1B gene have been described as the underlying cause of this condition. We report on the clinical findings in a 2½‐year‐old boy with some aspects out of the MWS‐spectrum in addition to unusual anomalies and a novel missense mutation in the ZFHX1B gene.

Monitoring of 4-hydroxybutyric acid levels in body fluids during vigabatrin treatment in succinic semialdehyde dehydrogenase deficiency

We report the successful treatment using low‐dose vigabatrin (21.5–34mg/kg/day) of a 10‐year‐old girl with succinic semialdehyde dehydrogenase (SSADH) deficiency We verified that 4‐hydroxybutyric acid (GHB) concentrations in serum, cerebrospinal fluid, and urine continuously decreased in parallel with significant clinical improvement. Our results suggest that GHB quantification in physiological fluids may be a useful laboratory parameter for monitoring efficacy of vigabatrin treatment in SSADH deficiency. Ann Neurol 2003;54:686–689

Identification of three novel plasminogen (PLG) gene mutations in a series of 23 patients with low PLG activity

Inherited severe hypoplasminogenaemia is a multisystemic disorder leading to deficient extravascular fibrinolysis. As a clinical consequence wound healing capacity of mucous membranes is markedly impaired leading to ligneous conjunctivitis and several other manifestations. Here we report the molecular genetic and clinical findings on 23 new cases with severe hypoplasminogenaemia. Homozygous or compound-heterozygous mutations in the plasminogen (PLG) gene were found in 16 of 23 patients (70%), three of which were novel mutations reported here for the first time (C166Y, Y264S, IVS10-7T/G). Compared to 79 previously published cases, clinical manifestations of the current group of patients showed higher percentages of ligneous periodontitis, congenital hydrocephalus, and involvement of the female genital tract. In contrast, involvement of the gastrointestinal or urogenital tract was not observed in any of the cases. Patients originated to a large extent (61%) from Turkey and the Middle East, and showed a comparably frequent occurrence of consanguinity of affected families and a greater female to male ratio than was derived from previous reports in the literature. Individual treatment of ligneous conjunctivitis included topical plasminogen or heparin eye drops, topical or systemic fresh frozen plasma, and surgical removal of ligneous pseudomembranes, mostly with modest or transient efficacy. In conclusion, the present study underscores the broad range of clinical manifestations in PLG-deficient patients with a trend to regional differences. Transmission of genetic and clinical data to the recently established Plasminogen Deficiency Registry should help to determine the prevalence of the disease and to develop more efficient treatment strategies.

Ligneous conjunctivitis, hydrocephalus, hydrocele, and pulmonary involvement in a child with homozygous type I plasminogen deficiency

Ligneous conjunctivitis is a rare and unusual form of chronic pseudomembranous conjunctivitis which usually starts in early infancy. Plasminogen deficiency has recently been associated with ligneous conjunctivitis. The disease may be associated with pseudomembranous lesions of other mucous membranes in the mouth, nasopharynx, trachea, and female genital tract and also with congenital hydrocephalus. In this report, a 1-month-old Turkish boy who had pseudomembranous conjunctivitis, occlusive hydrocephalus, and hydrocele is presented. After surgery for ventriculo-peritoneal shunt establishment, he developed inspiratory stridor, respiratory distress, and pulmonary atelectasis. Tracheal pseudomembranes were also demonstrated by bronchoscopy. Plasminogen antigen level and plasminogen activity were very low. Genomic DNA from the patient was screened for mutations in the plasminogen gene and a homozygous L650fsX652 mutation (deletion of 2081C) was detected. Both of his parents were heterozygous for this mutation. He died due to respiratory failure during follow-up. Conclusion: ligneous conjunctivitis related to type I plasminogen deficiency is relatively common in the Turkish population, however, mutations are heterogeneous and a common founder is unlikely.

Hyperactive mTOR pathway promotes lymphoproliferation and abnormal differentiation in autoimmune lymphoproliferative syndrome.

Autoimmune lymphoproliferative syndrome (ALPS) is a human disorder characterized by defective Fas signaling, resulting in chronic benign lymphoproliferation and accumulation of TCRαβ(+) CD4(-) CD8(-) double-negative T (DNT) cells. Although their phenotype resembles that of terminally differentiated or exhausted T cells, lack of KLRG1, high eomesodermin, and marginal T-bet expression point instead to a long-lived memory state with potent proliferative capacity. Here we show that despite their terminally differentiated phenotype, human ALPS DNT cells exhibit substantial mitotic activity in vivo. Notably, hyperproliferation of ALPS DNT cells is associated with increased basal and activation-induced phosphorylation of serine-threonine kinases Akt and mechanistic target of rapamycin (mTOR). The mTOR inhibitor rapamycin abrogated survival and proliferation of ALPS DNT cells, but not of CD4(+) or CD8(+) T cells in vitro. In vivo, mTOR inhibition reduced proliferation and abnormal differentiation by DNT cells. Importantly, increased mitotic activity and hyperactive mTOR signaling was also observed in recently defined CD4(+) or CD8(+) precursor DNT cells, and mTOR inhibition specifically reduced these cells in vivo, indicating abnormal programming of Fas-deficient T cells before the DNT stage. Thus, our results identify the mTOR pathway as a major regulator of lymphoproliferation and aberrant differentiation in ALPS.

Sequential decisions on FAS sequencing guided by biomarkers in patients with lymphoproliferation and autoimmune cytopenia

Clinical and genetic heterogeneity renders confirmation or exclusion of autoimmune lymphoproliferative syndrome difficult. To re-evaluate and improve the currently suggested diagnostic approach to patients with suspected FAS mutation, the most frequent cause of autoimmune lymphoproliferative syndrome, we prospectively determined 11 biomarkers in 163 patients with splenomegaly or lymphadenopathy and presumed or proven autoimmune cytopenia(s). Among 98 patients sequenced for FAS mutations in CD3+TCRα/β+CD4−CD8− “double negative” T cells, 32 had germline and six had somatic FAS mutations. The best a priori predictor of FAS mutations was the combination of vitamin B12 and soluble FAS ligand (cut-offs 1255 pg/mL and 559 pg/mL, respectively), which had a positive predictive value of 92% and a negative predictive value of 97%. We used these data to develop a web-based probability calculator for FAS mutations using the three most discriminatory biomarkers (vitamin B12, soluble FAS ligand, interleukin-10) of the 11 tested. Since more than 60% of patients with lymphoproliferation and autoimmune cytopenia(s) in our cohort did not harbor FAS mutations, 15% had somatic FAS mutations, and the predictive value of double-negative T-cell values was rather low (positive and negative predictive values of 61% and 77%, respectively), we argue that the previously suggested diagnostic algorithm based on determination of double-negative T cells and germline FAS sequencing, followed by biomarker analysis, is not efficient. We propose vitamin B12 and soluble FAS ligand assessment as the initial diagnostic step with subsequent decision on FAS sequencing supported by a probability-calculating tool.