Scientists at the National Institute of Child Health and Human Development (NICHD) have developed a new model for studying the destructive effects of AIDS in live tissue samples. The critical events in the development of AIDS take place in lymphoid tissue, but AIDS research has been hampered by the fact that an animal model of HIV infection that readily mimics human AIDS does not exist. Scientists also lack readily available laboratory techniques for closely mimicking, in vitro, HIV infection in the body (in vivo).
The NICHD scientists have overcome this limitation by culturing and infecting pieces of tonsil, which is composed largely of lymphoid tissue, obtained from tonsillectomies. With this advance, they have helped illuminate one of the central questions of HIV pathology--what triggers the eventual development of AIDS in people who carry HIV?
The finding appears in the March issue of Nature Medicine, and was reported by scientists Svetlana Glushakova, Jean-Charles Grivel, Wendy Fitzgerald, Andrew Sylvester, Joshua Zimmerberg, and Leonid Margolis.
The laboratory model, which allows HIV to be studied in the tissue in which it is usually found, consists of tiny (1mm) cubes of tonsil cultured on wet collagen sponges. The cubes, which retain their viability and native architecture for several weeks, can be infected with HIV (which multiplies and spills into the surrounding medium), so that they mount a response to immunological challenge. Such responses are the hallmark of lymphoid tissue. Thus, just as they would in the body, the blocks of lymphoid tissue make antibodies to tetanus toxoid or diphtheria toxoid (which are used to immunize people against tetanus and diphtheria), and they do so with much greater efficiency than isolated immune cells, underscoring the importance of the cell's environment to the cell's proper functioning.
With the help of these cultured, immunologically responsive, tonsil
Contact: Bob Bock
NIH/National Institute of Child Health and Human Development