TNFRSF1B and obesity due to melanocortin 4 receptor deficiency: O3-induced increases in BAL LIX, a neutrophil chemotactic factor, were not affected by obesity, TNFR2 deficiency, or anti–IL-13 treatment (Figure 6A) indicating that this chemokine does not account for the observed effects on BAL neutrophils (Figure 4B).