Mannose-binding lectin and the risk of HIV transmission and disease progression in children: A systematic review

BACKGROUND: Mannose-binding lectin (MBL) can activate the complement system by binding to carbohydrates, such as those presented on the HIV virion surface. It is unclear whether genetically determined MBL deficiency is related to vertical HIV transmission and disease progression in HIV-infected children. METHODS: A literature search of Medline, Embase and Cochrane Central Register identified all relevant studies on MBL and HIV infection in children. We extracted information on the characteristics of the study group, method of MBL analysis, outcome definitions, follow-up and the risk estimates. The validity of each study was assessed. RESULTS: Nine studies were retrieved. Most were of good validity, but risk adjustment for confounders was missing in 6 studies. Age, treatment and outcome definitions differed between the study groups. In most of the studies, MBL deficiency was associated with an increased frequency of vertical HIV transmission and an increased speed of disease progression. In the 2 most valid studies, carriers of variant genes had an increased odds ratio for transmission and an increased relative hazard for disease progression and central nervous system impairment, especially in children <2 years of age. CONCLUSIONS: MBL deficiency is associated with an increased risk of vertical HIV transmission. How this risk relates to other factors that influence transmission is unclear. The association between HIV disease progression and MBL deficiency is most pronounced in children <2 years of age, probably due to immaturity of their adaptive immunity.