Induction of CD4(+) T cell depletion in mice doubly transgenic for HIV gp120 and human CD4

It has been suggested that loss of uninfected T cells in HIV infection occurs because of lymphocyte activation resulting in cell death by apoptosis. To address the question of whether cross-linking of CD4/HIV gp120 complexes by antibodies were sufficient to induce T cell depletion in vivo, we developed an animal model of continuous interaction between human CD4 (hCD4), gp120 and anti-gp120 antibodies in the absence of other viral factors. Double-transgenic mice have been generated in which T cells express on their membrane hCD4 and secrete HIV gp120. Although these mice have hCD4/gp120 complexes present on the surface of T cells, they do not show gross immunological abnormalities, and they are able to produce anti-gp120 antibodies following immunization with denaturated gp120. However, double-transgenic mice with antibodies to gp120, when immunized with tetanus toroid, mount an IgG response that is significantly lower than that of double-transgenic mice without antibodies to gp120. Furthermore, the presence of anti-gp120 antibodies leads to CD4(+) T cell depletion and immunodeficiency in the absence of HIV infection. Thus, the antibody response to gp120 can lead to CD4(+) T cell attrition in vivo.