In situ immunophenotyping of lymphocytes/macrophages: grading of lymphadenopathy, staging and pathophysiology of HIV infection

Antibody from patients with acute human immunodeficiency virus (HIV) infection inhibits primary strains of HIV type 1 in the presence of natural-killer effector cells

The partial control of viremia during acute human immunodeficiency virus type 1 (HIV-1) infection is accompanied by an HIV-1-specific cytotoxic T-lymphocyte (CTL) response and an absent or infrequent neutralizing antibody response. The control of HIV-1 viremia has thus been attributed primarily, if not exclusively, to CTL activity. In this study, the role of antibody in controlling viremia was investigated by measuring the ability of plasma or immunoglobulin G from acutely infected patients to inhibit primary strains of HIV-1 in the presence of natural-killer (NK) effector cells. Antibody that inhibits virus when combined with effector cells was present in the majority of patients within days or weeks after onset of symptoms of acute infection. Furthermore, the magnitude of this effector cell-mediated antiviral antibody response was inversely associated with plasma viremia level, and both autologous and heterologous HIV-1 strains were inhibited. Finally, antibody from acutely infected patients likely reduced HIV-1 yield in vitro both by mediating effector cell lysis of target cells expressing HIV-1 glycoproteins and by augmenting the release of beta-chemokines from NK cells. HIV-1-specific antibody may be an important contributor to the early control of HIV viremia.

Relationship of lymphoid lesions to disease course in mucosal feline immunodeficiency virus type C infection

Feline immunodeficiency virus (FIV) infection typically has a prolonged and variable disease course in cats, which can limit its usefulness as a model for human immunodeficiency virus infection. A clade C FIV isolate (FIV-C) has been associated with high viral burdens and rapidly progressive disease in cats. FIV-C was transmissible via oral-nasal, vaginal, or rectal mucosal exposure, and infection resulted in one of three disease courses: rapid, conventional/slow, or regressive. The severity of the pathologic changes paralleled the disease course. Thymic depletion was an early lesion and was correlated with detection of FIV RNA in thymocytes by in situ hybridization. The major changes in thymic cell populations were depletion of p55+/S100+ dendritic cells, CD3- cells, CD4+/CD8- cells, and CD4+/CD8+ cells and increases in apoptosis, CD45R+ B cells, and lymphoid follicles. In contrast to thymic depletion, peripheral lymphoid tissues often were hyperplastic. Mucosally transmitted FIV-C is thymotropic and induces a spectrum of lymphoid lesions and disease mirroring that seen with the human and simian immunodeficiency virus infections.

HIV-1 infection stimulates T cell invasiveness and synthesis of the 92-kDa type IV collagenase

Tissue-specific localization of HIV-1-infected lymphoid cells may contribute to clinical manifestations of AIDS. Therefore we investigated the effect of HIV-1 infection on mechanisms of T lymphocyte invasion, a process required for movement of cells into and out of the circulation. In the present study, we demonstrate that HIV-1-infected human lymphocytes secrete increased amounts of the human 92-kDa type IV collagenase when compared to uninfected lymphocytes. Furthermore, HIV-1-infected lymphocytes degrade the extracellular matrix proteins collagen IV and fibronectin, and they are more invasive through a reconstituted basement membrane when compared to uninfected cells. The addition of either antibody to the 92-kDa collagenase or TIMP-2, a type IV collagenase inhibitor, abolishes invasive activity. These data suggest that HIV-1-infected lymphocytes express phenotypic characteristics that are consistent with an enhanced ability to leave the circulation and to localize in target tissues. Local viral infection or the release of viral proteins, cytokines, or proteolytic enzymes in tissues may contribute to pathogenesis.