Characteristics of IgA antibodies against HIV-1 in sera and saliva from HIV-seropositive individuals in different clinical stages.

IgA antibodies were analysed in sera and saliva from 40 HIV-1 seropositive individuals. The level of total IgA in serum was elevated according to the progress of the disease. IgA antibodies against p24 and gp160 were detected in the asymptomatic phase of infection. However, they declined in the symptomatic phases in contrast with IgG antibodies. Interestingly, three patients in the symptomatic phase who showed high levels of IgA antibodies were all in relatively good clinical condition. The IgG and IgA antibodies in saliva declined in the symptomatic phase. The level of IgG anti-p24 antibodies in saliva correlated with that in serum, suggesting that IgG anti-p24 antibodies in saliva originated from those in the serum. These results indicate that IgA antibodies are regulated independently from IgG antibodies and that the mucosal immune system is impaired early in the symptomatic phase of HIV infection, which starts with mucosal impairment. Detection of IgA antibodies may be useful for prognosis of the disease in HIV-infected individuals. The results indicate also that treatment for the impaired IgA mucosal immune system should be taken into consideration.