IgA subclasses in HIV disease: dichotomy between raised levels in serum and decreased secretion rates in saliva.

This study sought to determine IgA, IgA1 and IgA2 concentrations and secretion rates in unstimulated whole saliva and stimulated parotid saliva and IgA, IgA1 and IgA2 concentrations in serum from asymptomatic human immunodeficiency virus (HIV)-infected, acquired immune deficiency syndrome (AIDS) and control subjects. In whole and parotid saliva the mean IgA, IgA1 and IgA2 concentrations in the HIV and AIDS groups were lower than the control group (P < 0.05). Unstimulated whole and stimulated parotid saliva flow rates were lower in the HIV and AIDS groups compared with the control group, and reached statistical significance with respect to the mean parotid saliva flow rate in the AIDS group (P < 0.05). Mean IgA, IgA1 and IgA2 secretion rates in both the HIV and AIDS groups were significantly less than the controls (P < 0.05). In contrast, serum IgA, IgA1 and IgA2 concentrations were markedly raised in the HIV and AIDS groups compared with the control group (P < 0.001). There was no correlation between saliva and serum IgA concentrations within individuals. This study suggests that, in spite of the raised, polyclonally activated serum IgA concentrations associated with HIV infection, salivary IgA concentrations and secretion rates are reduced, emphasizing the dichotomy between systemic and secretory immunity.