Resistance of MBL gene-knockout mice to experimental systemic aspergillosis.

Mannose binding lectin (MBL) is a protein of the collectin family that appears important in resistance to invasive pulmonary aspergillosis. We assessed the role of MBL in experimental systemic aspergillosis. MBL-sufficient C57BL/6 (WT) mice and B6.129S4--Mb11(tm1Kata) Mb12(tm1Kata)/J MBL A and C gene-knockout (KO) mice were infected intravenously with different inocula of Aspergillus fumigatus conidia. WT and KO mice were dose-responsively susceptible. In no instance were the KO mice more susceptible than WT. At the highest inoculum, all WT and 90% of KO mice died on day 4 (P>0.05). Reduction of the inoculum to 5.5 x 10(6) conidia was lethal, but comparison showed KO mice less susceptible to lethal infection (P<0.015). At the lowest inoculum used, deaths of KO mice were delayed, but survival was not significantly different than WT (P>0.05). These results suggest MBL may play a deleterious role in systemic aspergillosis.