Ilan Dalal

Immune function in patients with Shwachman–Diamond syndrome

Shwachman–Diamond syndrome (SDS) is an inherited multisystem disorder characterized by exocrine pancreatic dysfunction and varying degrees of cytopenia. In addition, various immunological abnormalities have been noted. To clarify the issue of immunological competence or incompetence in SDS, we prospectively studied immune function in 11 patients with SDS. Seven suffered from recurrent bacterial infections and six from recurrent viral infections. Varying degrees of impairment were readily identified. All patients had neutropenia; total lymphocyte counts, however, were normal in all except one patient. Nine patients had B‐cell defects comprising one or more of the following abnormalities: low IgG or IgG subclasses, low percentage of circulating B lymphocytes, decreased in vitro B‐lymphocyte proliferation and a lack of specific antibody production. Seven out of nine patients studied had at least one T‐cell abnormality comprising a low percentage of total circulating T lymphocytes or CD3+/CD4+ cell subpopulations or decreased in vitro T‐lymphocyte proliferation. Five out of six patients studied had decreased percentages of circulating natural killer cells. Moreover, neutrophil chemotaxis was significantly low in all the patients studied. These data point to a major immunodeficiency component in SDS that places patients at heightened risk of infections, even if neutrophil numbers are protective. This finding broadens the definition of the syndrome substantially: it suggests that the SDS marrow defect occurs at the level of an early haematological–lymphocytic stem cell or that a combined marrow and thymic stromal defect accounts for the aberrant function of haematopoietic and lymphopoietic lineages.

The outcome of patients with hypogammaglobulinemia in infancy and early childhood

A 10-year prospective cohort study followed the evolution of antibodies in children less than 4 years of age with hypogammaglobulinemia. Three patterns were identified: in group 1, immunoglobulins and antibody production normalized;iin group 2, patients continued to have low IgG levels; and in group 3, IgG levels normalized but antibody levels were transient. Statistical analysis showed that invasive infection or low tetanus antibodies at presentation were associated with the development of significant humoral immunodeficiency.

Clinical utility of high-resolution pulmonary computed tomography in children with antibody deficiency disorders.

Objective. To assess the value of high-resolution computed tomography (HRCT) in determining the extent and significance of lung disease in children with antibody deficiency states. Materials and methods. Seventy HRCT scans performed on 37 children with various antibody deficiency disorders over a 5-year period were retrospectively scored using a previously described demerit scoring system (0–25 with 0 = worst, 25 = best). Points are subtracted from 25 with increasing severity of disease. The potential correlations between CT scores and clinical factors, including age at diagnosis, age at CT, type of immunoglobulin deficiency, length of respiratory symptoms before diagnosis, number of pneumonias before diagnosis, type, length and success of therapy, patient compliance and pulmonary function tests (PFTs), were assessed. Results. Of the 37 children, a demonstrated 22 abnormal scans (CT score ≤ 22). All nine demonstrated bronchiectasis with a lower lobe and right middle lobe predominance. Statistically significant correlations were seen between severity of lung disease (CT score) and length of respiratory symptoms before diagnosis (p = 0.01), success of therapy (P = 0.001) and PFTs (P = 0.0008). Of seven children who were followed with repeated scans, 4 of the 7 demonstrated CT scores which improved on high-dose intravenous immunoglobulin replacement therapy. Conclusion. HRCT is a useful adjunct to demonstrate the extent and severity of lung disease at diagnosis and during therapy. Correlation with clinical factors suggests a higher risk group needing more aggressive management.

Two novel mutations in a purine nucleoside phosphorylase (PNP)-deficient patient

Purine nucleoside phosphorylase (PNP) deficiency is a rare autosomal recessive disease, which presents clinically as severe combined immunodeficiency (SCID). We report here two novel mutations in the PNP gene that result in SCID phenotype, in a single patient. The maternal‐derived allele carries a C to T transition in exon 2 resulting in a premature stop codon at amino acid 57. The paternal‐derived mutation is a G to A transition at position +1 in intron 3, causing a complete skipping of exon 3 and a reading frameshift at the exon 2–exon 4 junction. The predicted polypeptide encoded by the aberrantly spliced mRNA terminates prematurely after only 89 amino acids. Both mutations predict severely truncated proteins resulting in a complete deficiency of PNP enzymatic activity, yet the development of profound immunodeficiency in this patient is greatly delayed.

Cerebral vasculitis associated with chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis is a heterogenous group of disorders, associated with a variety of autoimmune disorders and a broad spectrum of immune aberrations. We describe 2 patients with chronic mucocutaneous candidiasis who had cerebrovascular disease with severe neurologic sequelae. Results of angiography of cerebral vessels and brain biopsy in one were consistent with the diagnosis of cerebral vasculitis.

Immune function in patients with β thalassaemia receiving the orally active iron-chelating agent deferiprone

Short‐term deferiprone may reduce body iron in some patients with thalassaemia major. Concerns regarding potential immunosuppressive effects of deferiprone have been raised from results of animal studies and case reports in humans. We studied immune function in 57 thalassaemia patients: 36 treated with deferiprone (L1; CP020) and 21 treated with desferrioxamine (DFO). Circulating B lymphocytes were increased in all patient groups. No differences were detected between treatment groups in percentages of circulating lymphocytes, concentrations of IgG, IgM or IgA, specific antibody titres, complement levels, or in vitro lymphocyte proliferation. No clinically important infections were observed in any patient. These data suggest that no clinical or laboratory changes consistent with immunosuppression or immunodeficiency are observed during deferiprone therapy.

HYPOGAMMAGLOBULINEMIA OF INFANCY

In their classic report from 1956, Gitlin and Janeway 16 first coined the term transient hypogammaglobulinemia of infancy (THI). Although THI has been recognized for many years and despite significant progress in understanding the molecular basis and identifying the genes involved in the pathogenesis of many other forms of humoral immunodeficiencies (ID), little is known about this specific entity. This article summarizes previous studies and reports our long-term experience with THI.