الفهرس 
HEMOPHAGOCYTIC SYNDROMEOnly 14 pages are availabe for public view
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Abstract
We conducted a controlled prospective study comprising 25 patients fulfilling the Hemophagocytic lymphohistocytosis (HLH) diagnostic criteria of the Pediatric HLH Study group of the Histiocyte Society. The study was conducted in the pediatric Allergy and Immunology Unite, Children’s Hospital of Ain-Shams University after fulfilling the inclusion and exclusion criteria, during the period from April 2015 to June 2016. These patients were compared with 25 age and sex matched healthy controls.
After detailed history taking and clinical examination; laboratory assessment was done including complete blood counts, erythrocyte sedimentation rate, C- reactive protein, measurement of HLH markers (serum fibrinogen, fasting triglycerides, ferritin) in addition to flowcytometric measurement of αβ DN T cells. Evaluation was done at enrollment and at week 9 after the start of HLH induction treatment protocol.
All patients had platelets < 100 (x103/ul), ferritin>500 (ng/ml), fibrinogen <1.5 (g/l). Anemia was found in 76.0% while, 64.0% had ANC < 1 (x103/ul) and 16.0% had elevated liver enzymes. In 17 (68%) patients, infection was the trigger of HLH while it was malignancy in three (12%), and rheumatological disorders in two patients (8%). All patients received steroids while 18, 15, 8 and 6 of cases were treated by cyclosporine, etoposide, intravenous immunoglobulin and intrathecal methotrexate respectively.
At enrollment, 15 patients (60%) had elevated αβ DN T cells (>2%), with median (IQR) counts of 1.71 (1.25-2.12) that were significantly higher than the control values (median (IQR): 0.7 (0.4-0.8) (p<0.001). Initial αβ DN T cells counts of patients were also higher at enrollment as compared to results at the end of week 9 (median (IQR): 0.76 (0.45-1.17), p=0.018). Survivors (n=17 [68 %]) and non-survivors (n=8 [32%]) had comparable levels of αβ DN T cells at enrollment (p=0.861). An initial platelet count of less than 41.000/mm3 could discriminate between remission and mortality with sensitivity 76.47%, specificity 87.5% with AUC 0.842. Also, a percentage of αβ DN T cells of more than 2.79% could discriminate between remission and mortality with sensitivity 32.5%, specificity 100.0% with AUC 0.522. αβ DN T cells correlated positively with the liver enzyme ALT (p=0.019) and negatively with the CD4/CD8 ratio (p=0.023).
In conclusion, mild αβ DN T cell percentage elevations are not ALPS specific and may occur among HLH patients. This was linked to disease activity and to some extent to disease prognosis and severity. The small sample size constitutes the major limitation of the present study. Also, the lack of histological evidence of infiltration of αβ DN T cells in the organs and the lack of diagnostic verification by molecular studies could also be limiting factors. Wider scale studies with longer periods of follow up are needed to validate our conclusions to be able to properly anticipate a relation between ALPS and HLH.