Reduced Intensity Hematopoietic Stem Cell Transplant Rescues Immune Function and Corrects Pulmonary Alveolar Proteinosis in DCML Deficiency/GATA 2 Mutation

Abstract 2045

The novel syndrome of Dendritic Cell, Monocyte, B and NK lymphocyte (DCML) deficiency has recently been characterised and found to be caused by mutations in the transcription factor GATA-2 (Dickinson et al. Blood 2011, Hsu et al. Blood 2011). In this report we describe a series of 10 patients and show that there is a high risk of death unless curative haematopoietic stem cell transplantation (HSCT) is performed.

Our case series includes 10 patients; 4 sporadic cases and 6 cases from 2 pedigrees showing autosomal dominant inheritance. 7 patients died; of the 3 survivors, 2 were transplanted and show marked resolution of their disease with a follow up of 36 and 11 months, respectively. Causes of death in the patients who died include disseminated mycobacterium avium infection (2) H1N1 influenza (1) candidiasis (1) pulmonary alveolar proteinosis (2) and CMV pneumonitis (1). At least 8 patients had chronic HPV infection and 2 patients had autoimmune phenomena including inflammatory arthritis and erythema nodosum. One patient also developed lymphoma.

All patients had monocytopenia and decreased B and NK cells with normal T cells at presentation. Haemoglobin, platelets and neutrophil counts were within normal ranges or mildly reduced. In 4 patients, near absolute dendritic cell (DC) deficiency and elevated Flt-3 ligand was also confirmed. BM aspirate showed dysplastic megakaryocytes and increased fibrosis in some instances. Macrophages were present in dermis, bone marrow and lung, epidermal Langerhans cells were largely preserved and plasma cells were found in inflammatory lesions by immunohistochemistry. GATA-2 mutation was confirmed by Sanger sequencing in all cases.

Of the 2 patients treated with transplantation, the first patient presented aged 12 with disseminated BCG sepsis 6 months following BCG vaccination. Skin biopsy showed acid fast bacilli but no well-formed granulomata, and ongoing sepsis failed to respond to antitubercular therapy including addition of IFN gamma. The second patient presented to gynaecology services at the age of 20 with vulval intraepithelial neoplasia stage 3 (VIN3), and then to respiratory physicians a year later with breathlessness, productive cough, weight loss and night sweats; pulmonary alveolar proteinosis was diagnosed on biopsy. She continued to deteriorate despite whole lung lavage, and developed respiratory failure requiring 35% oxygen and nocturnal non-invasive ventilation (NIV). The patient's family history included two generations affected by haematological malignancy or respiratory illness in early adulthood, inherited in a fashion suggesting an autosomal dominant trait.

Both patients underwent reduced intensity allogeneic haematopoietic stem cell transplantation with PBMC from unrelated adult donors (patient 1 – 10/12 HLA match; patient 2 – 9/12); transplant conditioning was with Fludarabine 150mg/m², Melphalan 140mg/m² and Alemtuzumab 60mg (patient 1), and Fludarabine 150mg/m², Busulphan 6.4mg/kg, Alemtuzumab 60mg (patient 2). GVHD prophylaxis was with Ciclosporin and Mycophenolate Mofetil. Both transplants were uneventful.

32 months post-transplantation, patient 1 is well and off all medication. The monocyte count, lymphocyte subsets and immunoglobulins are normal and there were good responses to tetanus and HIB vaccinations. Chimerism shows 100% donor myeloid and B cells and 85% donor T cells. 9 months post-transplantation patient 2 has improved significantly and no longer requires oxygen or NIV. Lung function tests and radiology have significantly improved. Monocytes are in the normal range and chimerism shows 100% donor CD15 and 85% donor CD3. Follow-up continues with gynaecology for VIN3 associated with HPV16/18 infection. Neither patient has developed GVHD.

Here we show that DCML deficiency caused by GATA-2 mutation incurs a high risk of mortality due to infection or respiratory failure unless treated by HSCT. Rapid correction of both immunodeficiency and pulmonary alveolar proteinosis is possible, even in the context of severe infection or respiratory failure, using reduced intensity conditioning. The absence of GVHD in both these cases, despite significant HLA-mismatching, may reflect the absence of recipient DC at transplantation.