Romero et al.21, who evaluated levels of IgA, IgG, and IgM in saliva of healthy children aged3 to 12 years with gingivitis, found a direct relationship between IgM and gingivalindex, and suggested two possible interpretations for this finding: the activationof IgM production as a response to an antigenic challenge leading to tissueinflammation or the increased exudate as a result of inflammation generates more IgMin saliva. The gene discussed is CD40LG; the disease is gingivitis.