Comparison of Th1/Th2 cytokine profiles between primary and secondary haemophagocytic lymphohistiocytosis

Abstract

Background: Haemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder of immune regulation, and HLH patients with mutations in genes including PRF1, UNC13D, STX11, STXBP2, SH2D1A, XIAP, and ITK were reported to be primary HLH. Due to the different treatment options, the differentiation between primary and secondary HLH is critical. Our previous studies have showed that a Th1/Th2 cytokine profile is diagnostic for HLH, yet the cytokine profiles between primary and secondary HLH have not been compared. The aim of the study was to test whether the Th1/Th2 cytokine profile could be used as a tool to differentiate between primary and secondary HLH.

Methods: A total of 45 hospitalized Chinese children with HLH during the period of February 2010 through September 2012 were enrolled in the study. Fifty healthy children were enrolled as controls. Primary HLH related genes were sequenced using genomic DNA samples. The Th1/Th2 cytokine levels including interferon-γ (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-10, IL-6, IL-4 and IL-2 were quantitatively determined by cytometric bead assay techniques.

Results: Primary HLH group (n = 4) included one patient with biallelic heterozygous mutations in PRF1 gene, and three patients with hemizygous mutation in SH2D1A gene. Based on the available genetic data, the other 41 patients were classified into the secondary HLH group. When compared the cytokine levels between the two groups, IL-4 level in primary-HLH was significantly lower than that in secondary HLH (P = 0.025), while IFN-γ level in primary HLH had a tendency of statistically lower than that in secondary HLH (P = 0.051). Area under receiver operating characteristic (ROC) curves of IL-4 and IFN-γ, IL-10, TNF-α, IL-2, and IL-6 levels were 0.841, 0.799, 0.506, 0.494, 0.457, and 0.250, respectively. ROC curves showed that 1.7 pg/ml of IL-4 had sensitivity and specificity for differentiation between primary and secondary HLH as 70.7 and 100.0 %, while 433.9 pg/ml of IFN-γ had sensitivity and specificity as 51.2 and 100.0 %, respectively.

Conclusions: HLH patients with lower IL-4 and IFN-γ levels have higher possibility to be primary HLH. The cytokine profile may be used as an additional tool for the quick differential diagnosis between primary and secondary HLH.

Keywords: Cytokines; Haemophagocytic lymphohistiocytosis; Interferon-γ; Interleukin-4.

Fig. 1

Comparisons of serum cytokine concentrations (pg/ml) among control, primary HLH, and secondary HLH. a IL-2; b IL-4; c IL-6; d IL-10; e TNF-α; f IFN-γ. The center horizontal line of the central box is the median (50th percentile), the bottom and top of the box are the 25th and 75th percentiles. The whiskers extend from each end of the box to the 5th and 95th percentiles of the values, respectively. Outliers are the data with values beyond the 5th and 95th percentiles

Fig. 2

ROC curves of IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ between primary HLH and secondary HLH. The diagonal line is the reference line

Fig. 3

Degranulation results of healthy controls, primary HLH cases, and pecondary HLH cases. Shapes represent individual subjects, while horizontal bars show the mean in each group