Finally, basophil chemotactic factors such as CCL2 may also be important for basophil migration in asthma patients, similar to anaphylaxis.50 This is supported by recent observations that CCL2 is released by airway smooth muscles in asthma patients, and that levels of CCL2 are increased in the serum of asthma patients.110 However, substantially broader studies are required to confirm or refute these speculations. This evidence concerns the gene CCL2 and asthma.