Correlation of the percentage of activated, CD3 + DR + lymphocytes to serum neopterin level in HIV-seropositive haemophiliacs

The percentage of activated, CD3+ DR+ and CD8+ Leu7+ lymphocytes and the serum neopterin concentration were determined in 17 HIV-seropositive and 10 HIV-seronegative haemophiliacs and in 11 healthy control subjects. All three parameters tested were found to be significantly higher in the seropositive patients than in the seronegative controls. In the seropositive group, a significant positive correlation was found between the neopterin levels and the percentage of CD3+ DR+ cells. By contrast, no significant negative or positive correlation was observed between the neopterin levels and the percentage of the CD8+ Leu7+ subset. These data suggest that in the HIV-infected patients the activated T cells responsible for the stimulation of macrophages to produce neopterin are those that do not carry CD8.

Effect of pepsin treatment on the HIV envelope and core antigens

In order to clarify whether HIV-1 core and env antigens are destroyed during pepsin treatment, used previously for detecting HIV-1 core and env antibodies hidden in circulating immune complexes, purified recombinant env and core antigen preparations were treated with pepsin. Core antigen was found to be extremely sensitive to this enzyme. By contrast, the antigenicity of the purified env antigen was not destroyed and was even increased after pepsin treatment, performed under identical conditions. These findings suggest that after pepsin digestion the core-anti-core immune complexes do not reconstitute because of the loss of antigenicity of the core antigen. By contrast, the lack of binding after neutralization to the env antigen of the F(ab')2 fragment of the anti-env antibody, cleaved by pepsin from the immune complexes, is probably due to other factors.

A simple method for detecting HIV antibodies hidden in circulating immune complexes

A method previously used for studying the specificity of antibody components of circulating immune complexes in different diseases has been applied to analyse circulating immune complexes in HIV-infected patients. Antibodies against HIV antigens hidden in circulating immune complexes were studied in 14 sera from 13 patients with asymptomatic HIV infection (group 1) and in 11 sera from seven patients with HIV symptoms (group 2). HIV antigen-coated wells from the Vironostika kit as well as core and envelope antigen-coated beads from the Abbott confirmatory kit were used as solid-phase antigen. Using the Vironostika plates, HIV antibodies were demonstrated in circulating immune complexes in three and five sera in groups 1 and 2, respectively. Anti-core antibodies hidden in circulating immune complexes were present in three out of eight and two out of nine sera, respectively, in groups 1 and 2, whereas anti-envelope antibodies were present in circulating immune complexes in one out of eight and six out of nine sera in the same groups. These findings demonstrate that not only core-anti-core but also envelope-anti-envelope immune complexes are present in the sera of HIV infected patients.