RESUMO
The investigation was outlined to study antibodies against some antigens of extracellular microbes associated with inflammation in broncho-pulmonary system and accessory nasal sinus - Staphylococcus aureus, Streptococcus pneumoniae, Branhamella catarrhalis - in individuals (18 patients) with different stages of HIV-infection. The level of antibodies was measured by ELISA and their Ab affinity was assessed by sodium thiocyanate-induced alteration of antibody-antigen interaction. To determine interrelations between antibody production and CD4(+) T lymphocyte number flow cytometry was employed. At the early stages of HIV-infection the levels of antibodies against Streptococcus pneumoniae and GMGM decreased, in comparison with HIV-negative donors. During HIV-infection course levels of antibodies against Staphylococcus aureus peptidoglycan, its antigen determinants and Streptococcus pneumoniae somatic antigen increased. Time affinity of antibodies against these antigens decreased. At all stages of HIV-infection and at all forms of its complications, we observed an increase of titer of antibodies to GMDP, antigenic determinant of peptidoglycan, which carried immunostimulating and adjuvant activities. HIV patients with CD4(+) T lymphocyte number <200 cells/&mgr;l displayed higher level of antibodies to bacterial antigens than that in patients with CD4(+) T lymphocyte number 200-400 per ml. The development of humoral immune response against some of extracellular bacteria is characterized, on the one hand, by their increased levels, and on the other hand, decreased affinity.
RESUMO
The natural antibodies against glucosaminylmuramyl dipeptide (GMDP), the epitope of peptidoglycan of bacterial cell wall, isolated from human serum by thermal extraction possess a capability to cross-react with determinant of glycan chain - tetrasaccharide consisting of N-acetylglucosamine and N-acetylmuramic acid. The intensity of interaction of natural anti-GMDP-antibodies with specific ligand is significantly higher than with tetrasaccharide. The natural antibodies against tetrasaccharide carry properties of heteroclitic antibodies, i.e. the intensity of their interaction with heterologous ligand, GMDP, is significantly higher than with homologous one, tetrasaccharide GMGM. GMDP is supposed to be specific antigenic peptidoglycan determinant against which the antibodies reacting with various intensity to homologous (GMDP) and relative (tetrasaccharide) hapten are formed in the process of natural immunization.
