The specificity of IgA against food, inhalant, bacterial and fungine antigens as well as for HIV-1 proteins was investigated in 14 HIV-1-infected children (CDC stage P-2) and 15 controls. IgA against food- and inhalant antigens as well as against tetanus toxoid were significantly more often present in the HIV positive children than in controls. No difference between the two groups was present for IgA against Candida albicans. A significant increase of substance P, a strong IgA synthesis inducing neuropeptide, was demonstrated in the plasma of HIV-1 infected children. In conclusion, high levels of IgA seem to reflect a complex immune dysfunction in which many factors are involved. The importance of neuroimmune dysregulation is discussed.