SERPINA1 and infection: Furthermore, MDM differentiated into a pro-inflammatory phenotype using GM-CSF secrete even higher levels of AAT than MDM differentiated into an anti-inflammatory phenotype using M-CSF.43 LPS further increases gene expression of AAT in MDM, suggesting that exposure to gram negative bacteria in the lungs may drive AAT release from macrophages, which will contribute to the anti-proteinase activity during infection.