MBL2 polymorphism and risk of severe infections in multiple myeloma patients receiving high-dose melphalan and autologous stem cell transplantation

Severe infections related to treatment are common in patients with multiple myeloma (MM). Genetic polymorphisms of the immune system may influence the risk of infections. Mannan-binding lectin (MBL) is part of the innate immune system, and individuals homozygous for wild-type MBL encoding gene (MBL2) have a well-functioning MBL pathway of complement activation, in contrast to individuals carrying one or two variant alleles. We evaluated 113 courses of high-dose melphalan and autologous stem cell transplantation ( ASCT) in patients with MM. Patients homozygous for wild-type MBL2 had a significantly reduced risk of septicaemia during the ASCT procedure compared with patients carrying variant MBL2: Odds Ratio (OR) 0.19 (95% CI: 0.04-0.77), (P=0.02) in multivariate analysis. The risk of Common Toxicity Criteria grade 3-4 infections in general was not affected by wild-type MBL2: OR 1.20 (95% CI: 0.52-2.78), (P=0.67). The findings indicate that MBL to some extent protects against the most severe infections during ASCT.