Langerhans cells in HIV-1 infection.
The skin-specific immune surveillance system protects against invading microorganisms and transformed cells expressing tumor-specific neoantigens. This system includes antigen-presenting Langerhans cells, dermal and epidermal T lymphocytes, cytokine-producing keratinocytes, and draining peripheral lymph nodes. In patients infected with human immunodeficiency virus-1 (HIV-1), this surveillance system appears to be compromised, as evidenced by a reduction in the epidermal Langerhans cell population. Because human epidermal Langerhans cell express surface-bound CD4 antigens, HLA-DR antigens, and Fc-IgG receptors, all of which are involved in HIV-1 binding to, or entry into, the target cell, the reduction in Langerhans cells in patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) may be a direct consequence of HIV-1 infection and subsequent injury to Langerhans cells. Detailed ultrastructural studies have confirmed moderate to severe morphologic damage in some Langerhans cells of such patients and the presence of HIV-1-like particles on Langerhans cell surface membranes and in the extracellular spaces. The biologic consequences of Langerhans cell infection by HIV-1 could be either impaired antigen presentation function of viable Langerhans cells or possible transmission of the retrovirus to the T-cell compartment in skin or lymph nodes, with subsequent depletion of CD4+ T cells via widespread syncytia formation between HIV-1-infected and noninfected cells. The facts that herpes simplex virus, specific cytokines, and ultraviolet B radiation can activate signals for HIV-1 expression and that epidermal cells can elaborate large amounts of cytokines, particularly with enhanced ultraviolet B exposure, may have important clinical implications for HIV-1-infected patients.
Stingl
G
G
Department of Dermatology I, University of Vienna Medical School, Austria.
Rappersberger
K
K
Tschachler
E
E
Gartner
S
S
Groh
V
V
Mann
D L
DL
Wolff
K
K
Popovic
M
M
D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology / Q000473:pathology*; D015497:HIV-1; D006801:Humans; D007801:Langerhans Cells / Q000276:immunology* / Q000648:ultrastructure; D012871:Skin Diseases / Q000276:immunology / Q000473:pathology*