01988nas a2200133   4500000000100000008004100001260001900042100001800061700001400079700002400093245005400117856011000171520157300281       2022                            d  bAuthorea, Inc.1 aOLIVEIRA FJFD1 aGrumach A1 aConstantino-Silva R00aLectin pathway influences the severity of leprosy  uhttps://www.authorea.com/users/469727/articles/562380/master/file/data/full%20version/full%20version.docx3 a<p>This study aimed to evaluate the influence of the lectin pathway proteins Mannose-binding lectin (MBL) and ficolins (FCNs) MBL and FCN3) on leprosy’s susceptibility and severity. We studied patients with a confirmed diagnosis of leprosy (n=90) and their healthy household contacts (n=79). We have also analyzed a subgroup of patients under 15 years of age (n=35), compared to their family contacts (n=20). Higher levels of FCN3 were identified in patients sample (n=90) with undetermined clinical form (419.7 ng/ml), compared to (343.8ng/ml) virchowian (p=0.033) and no disability form (381.2 ng/ml). Higher levels of FCN3 were also seen for disability grade 1 compared to grade 2 (343.2ng/ml and 327.1 ng/ml), respectively (p=0.031). In patients &lt; 15 years of age, the highest levels of FCN3 occurred in those with undetermined clinical form (436.6 ng/ml) in comparison with dimorphic (368.7 ng/ml) and virchowian forms (321.2 ng/ml) (p=0.013). We have identified higher levels of FCN3 among disability grade 0 (386.7 ng/ml), in comparison with grade 1 (310.1 ng/ml) and 2 (268.3 ng/ml) in children patients (p=0.008) with no sequelae (399.1 ng/ml) versus leprosy reaction type 1 (299 ng/ml) (p=0.009). Patients &lt;15 years of age had higher MBL levels (4.455 ng / ml) compared to those &gt; 15 years (2.342 ng / ml) (p = 0.018). Serum MBL and FCN3 levels do not seem to influence the acquisition of M. leprae infection.Higher levels of FCN3 were associated with less severe sequelae and lower disability grade for adults and patients &lt; 15 years old</p>