Studies on the mechanism of complement-mediated inhibition of antibody binding to HIV gp41.
We have previously demonstrated that HIV envelope gp41 binding to specific antibodies decreases after preincubation of fluid-phase gp41 in normal human serum. This inhibition is proven to be mediated by the classical complement pathway. In this study recombinant gp41 (rgp41) and/or synthetic peptides were preadsorbed to solid phase, and then complement (normal human serum/heated human serum/purified Clq/heated Clq) and anti-gp41 antibodies were added either after each other or simultaneously, and the amounts of bound antibody, and deposited C3b, C4b and Clq were measured. Complement-dependent inhibition of antibody binding to solid-phase rgp41 was found, and Clq seems to be at least partially responsible for this phenomenon. Heating of Clq did not affect this process. Higher amounts of anti-gp41 antibodies significantly and dose-dependently enhanced C4b and C3b fixation to solid-phase rgp41. In the case of synthetic peptides corresponding to the immunodominant region of gp41, significant antibody binding to the solid-phase peptides was also detected, and pretreatment of peptides preadsorbed to solid phase with normal human serum almost totally abolished the antibody binding.
Hidvégi
T
T
National Institute of Haematology, Blood Transfusion and Immunology, Budapest, Hungary.
Prohászka
Z
Z
Ujhelyi
E
E
Thielens
N M
NM
Dierich
M P
MP
Hampl
H
H
Arlaud
G
G
Nagy
K
K
Füst
G
G
D000595:Amino Acid Sequence; D000937:Antigen-Antibody Reactions / Q000276:immunology; D015922:Complement C1q / Q000276:immunology; D003179:Complement C3b / Q000276:immunology; D015935:Complement C4b / Q000276:immunology; D003165:Complement System Proteins / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D015483:HIV Antibodies / Q000276:immunology*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology
D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41; D010455:Peptides; D011994:Recombinant Proteins; D015922:Complement C1q; D003179:Complement C3b; D015935:Complement C4b; D003165:Complement System Proteins