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INTRODUCTION: Henoch-Schönlein Purpura (HSP) is a common vasculitis in children, and the unbalance of T-helper 1/T-helper 2 plays an important part in its pathogenesis. Mannose-binding lectin (MBL) is an important component of innate immunity and related with a lot of diseases with immunologic derangement. However, we do not know the relationship between MBL and HSP. OBJECTIVE: We aimed to explore the serum level and gene polymorphisms of MBL and the levels of interleukin 10 (IL-10), IL-12, and IL-18 in supernatant of peripheral blood mononuclear cells of children with HSP and HSP nephritis (HSPN) and of healthy children. METHODS: The concentrations of MBL and IL-10, IL-12, and IL-18 were measured by enzyme-linked immunosorbent assay: MBL gene polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism and polymerase chain reaction with sequence-specific primers. RESULTS: The serum MBL levels in the 23 children with HSP were not significantly different from 27 children with HSPN (P = .95) or 18 normal children. The levels of IL-18 in the supernatant of peripheral blood mononuclear cells in the 3 groups were not significantly different from each other (P = .47, .15, and .14). The levels of IL-10 in children with HSP and HSPN were not different from each other (P = .70), but both were significantly different from those in the normal children (P = .04 and .01). The levels of IL-12 in children with HSP were different from those in the children with HSPN (P = .04). The MBL promoter genotype and the frequency of alleles were not different between the children with HSP and HSPN or between those 2 groups compared with the normal group. CONCLUSIONS: IL-12 probably plays an important role in the renal involvement in HSP. The position of MBL in the pathogenesis of HSP and HSPN remains to be confirmed.

INTRODUCTION: Mannose-binding lectin (MBL) is a plasma collectin and is considered an important component of innate immunity. Its plasma concentration is, for the most, part genetically determined by a series of single nucleotide polymorphisms located both in the structural gene and in the promoter region. MBL deficiency may be associated with increased susceptibility to infectious disease and autoimmune disorders. OBJECTIVE: Our goal was to establish the reference serum level of MBL in children, investigate the correlation between MBL gene polymorphisms and its serum level in Chinese Han nationality, and MBL gene polymorphisms and serum level in children with recurrent respiratory tract infections. METHODS: The concentrations of oligomerized MBL in plasma were measured by enzyme-linked immunosorbent assay, and MBL gene polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism and polymerase chain reaction with sequence-specific primers. RESULTS: The median MBL level in 470 normal children was 2536 ng/mL (range: 0–7860 ng/mL), and P2.5 to P97.5 was 161 to 5070 ng/mL. Two promoter polymorphisms, -550 and -221, and coding variants at codon 54 of the MBL gene affected the protein level significantly, and the most frequent genotype in Hans was HYPA/HYPA. Serum MBL levels were significantly lower in patients with recurrent respiratory tract infections (RRTIs) compared with healthy controls (H = 6.661; P < .05), and the frequency of the promoter LXP haplotype was significantly higher in patients with RRTIs than in controls (χ2 = 4.71; P = .03). The prevalence of the B allele in patients with RRTIs was higher than that in controls, but the difference did not reach significance (χ2 = 0.18; P > .05). CONCLUSIONS: The MBL reference value in China is 161 ng/mL. Children with MBL concentrations of