VIP restores natural killer cell activity depressed by hepatitis B surface antigen.

Vasoactive intestinal peptide (VIP) has recently been shown to bind to human lymphocytes and modulate immune functions. The ability of VIP in restoring natural killer (NK) cell activity depressed by hepatitis B surface antigen (HBsAg) has been investigated in the present research. Human lymphocytes were incubated with HBsAg and, after washing, a 4-hr cytotoxicity assay was performed. VIP was coincubated with lymphocytes during the preincubation with HBsAg or, alternatively, throughout the cytotoxicity assay. The study revealed that VIP, either preincubated or coincubated in the 4-hr assay, strongly restores NK cell activity depressed by viral antigen. This is noteworthy considering that a number of lymphocyte modulators such as interferons fail in restoring viral-dependent NK cell activity depression. In contrast with previous reports, even when coincubated in the 4-hr assay, VIP is a strong activator of NK cell activity. Further studies will be required to understand which mechanisms are involved in the interrelation between VIP and NK cells during viral infections.

[Specific IgA against multiple antigens as expression of immunologic deregulation in HIV-positive children]. / IgA specifiche contro antigeni multipli come espressione della disregolazione immunologica nel bambino HIV-positivo.

B-cell dysfunction in HIV-infected children is reflected by hypergammaglobulinemia and high levels of serum IgA. Little is known about antibody specificity since only a small portion of serum IgA appears to be directed against HIV proteins. In the present study the specificity of IgA antibodies against food, inhalant, bacterial and fungi antigens were evaluated in a population of HIV infected children. ELISA method was used for antibody testing. Our results show that in 84.6% of patients IgA against at least one food antigen are present. IgA against inhalant allergens were present in most of HIV-infected children but in none of controls. As for anti-tetanus toxoid antigens and anti-fungi antigens, though present in higher percentage in patients, specific IgA were found also in healthy children. If a gastrointestinal dysfunction might be supposed as the cause of presence of anti-food antigen IgA, it is difficult to consider this factor as the cause of presence of specific IgA directed against different antigens. It is possible to postulate that an immunologic dysregulation based on an imbalance between Th1 and Th2 cells or on higher levels of IL-5 and/or IL-6 may lead to a misfunction of B cell and consequently to hypergammaglobulinemia with high IgA levels.

High levels of IgA in HIV-1-perinatally-infected children. Antigen specificity and possible role of increased substance P plasma levels.

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.