CD4 and obesity due to melanocortin 4 receptor deficiency: Obesity complicates classic T helper 2 cells (Th2) inflammation; e.g., in obesity, eosinophilic airway inflammation is altered and eosinophil transport into the airway lumen is altered, and obesity biases CD4+T cells toward T helper 1 cell (Th1) polarization (Phull et al., 2017).