Insufficient acute stress-induced activation of cortisol secretion was previously shown in subjects with mild and moderate depression (Garcia et al., 2011), and ghrelin-reactive free IgG may play a role in improving ghrelin's protective role during stress (Lutter et al., 2008). We could not confirm this hypothesis in our study, as there was no significant associations between ghrelin-reactive free IgG and cortisol responses. But, it would be interesting to study such associations in patients with depression.