MAOB and asthma: On the other hand, platelet MAO-B activity differed significantly between smoking and non-smoking healthy subjects (p = 0.008, U = 1143.0, Mann-Whitney test), as well as between smoking and non-smoking asthma patients (p = 0.01, U = 287.0, Mann-Whitney test), suggesting lower platelet MAO-B activity in smoking subjects in both groups.