The other study on severe asthma demonstrated increases in IL-4 and -5 levels and neutrophil ratios in BAL of severe asthmatics with a high level of IL-13 in BAL compared to those with low of BAL IL-13 and moderate correlation of increases in IL-13 level and neutrophil ratios in BAL with an abundance of potentially pathogenic microbes in BAL of asthmatics [169]. This evidence concerns the gene IL13 and asthma.