Visceral Leishmaniasis May Unmask X-linked Hyper-IgM Syndrome

Excerpt

We report a 4-year old male born to non-consanguineous Caucasian parents, suffering from recurrent pneumonia since since the age of 5 months, including an episode of multilobar pneumonia requiring Pediatric Intensive Care Unit (PICU) admission. At 16 month-old he suffered from pneumococcal sepsis and pneumonia; humoral immunodeficiency was suspected at that time. The patient had impaired antibody response to polysaccharides and protein antigens. Nephelometry revealed IgG serum levels below the third percentile, with absent IgA and normal IgM concentration. Flow cytometry showed adequate T-cell phenotype but altered B-cell compartment due to lack of memory B-cells suggesting a class switch recombination (CSR) defect. Additionally, CD40L expression upon T-cell activation was impaired (Fig. 1 a). Lymphoproliferative function was normal (PHA, CD3 and PMA + ionomycin -data not shown-). Gene sequencing yielded a novel mutation in CD40LG, a duplication of G in codon 167 (c.dup500) leading to stop in codon 200, causing X-linked Hyper IgM (X-HIGM) also known as Hyper IgM type 1 (Fig. 1 b). [ 1] Intravenous gammaglobulin replacement was started maintaining serum Ig levels over 600 mg/dl.One year after diagnosis of X-HIGM, he was admitted because of 9-day fever with no other symptoms. Physical exam revealed fever of 39.5 °C in a well-appearing child. His spleen was enlarged extending 3 cm below the left costal margin. WBC revealed pancytopenia with no blasts in peripheral blood smear. Bone marrow aspirate showed macrophages with intracellular forms of Leishmania amastigotes, and a diagnosis of visceral leishmaniasis was made, so Visceral Leishmaniasis was diagnosed (PCR techniques were unavailable at that time). He was treated with liposomal amphotericin B, 4 mg/kg daily for two weeks, then monthly for the next twelve months. He became afebrile 48 h after receiving the first dose of liposomal B amphotericin. No recurrence of leishmaniasis were observed for 6 years.

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