The Role of MASP1, MASP2, and Mannose-Binding Lectin in the Immune Response to Hepatitis B Vaccination in Infants

<b>Background:</b> Hepatitis B vaccination is the most effective strategy for preventing chronic hepatitis B virus (HBV) infection; however, interindividual variability in vaccine-induced antibody responses remains a significant challenge in the field. Innate immune components, particularly lectin complement pathway proteins such as mannose-binding lectin (MBL), mannose-associated serine protease 1 (MASP-1), and mannose-associated serine protease 2 (MASP-2), may contribute to this variability in outcomes. This study aimed to evaluate the association between serum MBL, MASP-1, and MASP-2 levels, birth weight, and humoral response to hepatitis B vaccination in infants. <b>Methods:</b> This single-center prospective observational study included 37 term infants who received hepatitis B vaccinations at birth, 1 month, and 6 months of age according to the national immunization schedule. Venous blood samples were collected at month 6, before, and month 7 after the 3rd vaccine dose. Serum MBL, MASP-1, MASP-2, and antiHB levels were measured using commercial ELISA and chemiluminescence assays. Data were analyzed using non-parametric statistical tests and Spearman's correlation analysis. <b>Results:</b> AntiHB levels increased significantly following vaccination (median Pre-3rdVac: 125.8 mIU/mL; Post-3rdVac: 609.7 mIU/mL; <i>p</i> < 0.001). MASP-1 concentrations also showed a significant Post-3rdVac increase (median Pre-3rdVac: 809.52 ng/mL; Post-3rdVac: 1133.93 ng/mL; <i>p</i> = 0.019). Birth weight was positively correlated with both MASP-1 levels (<i>r</i>_s = 0.492, <i>p</i> = 0.004) and changes in MASP-1 concentrations (<i>r</i>_s = 0.524, <i>p</i> = 0.002) after the third dose. In addition, MASP-1 levels were positively associated with antiHB levels (<i>r</i>_s = 0.385, <i>p</i> = 0.030) and Post-3rdVac antiHB titers (<i>r</i>_s = 0.493, <i>p</i> = 0.004). In contrast, serum MBL and MASP-2 concentrations were not significantly associated with antiHB levels before or after vaccination. <b>Conclusions:</b> MASP-1, but not MBL or MASP-2, is associated with the magnitude of the antibody response to hepatitis B vaccination in infants. These findings suggest that specific components of the lectin pathway may influence vaccine-induced immunity, independent of MBL. Further large-scale studies incorporating genetic and functional analyses are warranted to clarify the mechanisms by which lectin pathway proteins shape hepatitis B vaccine response.