HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints/Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ruiz, M. E. Articles by Hendrix, M. J.C. Search for Related Content PubMed PubMed Citation Articles by Ruiz, M. E. Articles by Hendrix, M. J.C.

Arrest of In Vitro T Cell Differentiation of Normal Bone Marrow-Derived CD34⁺ Stem Cells with Thymic Epithelial Fragments from Children with AIDS

^a The Pediatric Research Institute,
^b Department of Pediatrics, Saint Louis University School of Medicine, St. Louis, Missouri, USA

Key Words. Pediatric AIDS • HIV • CD34⁺ stem cells • Thymic epithelial fragment model

Correspondence: Dr. Margaret E. Ruiz, Warren Grant Magnuson Research Clinical Center, Building #10, National Institutes of Health, Bethesda, Maryland 20892, USA.

A novel approach is presented to assess the ability of thymic tissues obtained from children with end stage AIDS to attract normal bone marrow (BM)-derived CD34⁺ (lineage negative) stem cells (SCs) and support lymphopoiesis in vitro. Chemokinesis of BM-derived CD34⁺ SCs was analyzed by time-lapse videomicroscopy to ascertain whether an alteration in SC motility could contribute to abnormal thymopoiesis under conditions of HIV infection. The migration of SCs derived from an HIV⁺ donor into thymic tissue was not significantly altered compared to normal controls, as were normal SCs migrating toward thymic epithelial cell monolayers derived from an HIV⁺ patient. Thymic tissue obtained from children with AIDS contained nests of CD34⁺ SCs identified by immunofluorescence, indicating SC homing to the thymus is apparently supported in HIV infection. The ability of HIV-affected thymic epithelial fragments to support lymphopoiesis was determined by examining the initial thymocyte populations present, compared to thymocytes produced de novo in T cell-depleted thymic fragments, following a single pulse of lineage negative CD34⁺ CD38^– SCs. In comparison to normal controls, thymocytes derived from the HIV-affected thymic epithelial fragment coculture had an increased percentage of triple negative thymocytes (28% of lymphocytes from HIV-affected tissue versus 1.5% in controls, p < 0.01) and a decreased percentage of double and single positive CD4⁺ thymocytes. However, CD3⁺CD8⁺ TCRß⁺ expression was comparable to control cultured thymic epithelial fragments indicating that HIV-affected thymic epithelia were capable of supporting the development of the CD8⁺ lineage. In an effort to extend the information obtained to date from the histological examination of HIV-affected thymic tissue, select patient thymic tissues were maintained in culture to evaluate the capacity of undifferentiated thymic epithelial cell guirlandes to differentiate in vitro. A partial regeneration of certain subpopulations of the thymic epithelium defined by TE-4 monoclonal antibody (mAb) and CDR2 mAbs occurred during the in vitro culture. The epithelial and mesenchymal components of thymic tissues were distinguished by immunostaining for keratins (indicative of epithelium) and vimentin (a mesenchymal marker). Further evaluation of the modulation of HIV thymus, with respect to the testing of new therapeutic strategies on SCs, will be possible with this in vitro model.

This article has been cited by other articles:

				A. P. Knutsen, S. T. Roodman, J. J. Freeman, K. R. Mueller, and J. D. Bouhasin Inhibition of Thymopoiesis of CD34+ Cell Maturation by HIV-1 in an In Vitro CD34+ Cell and Thymic Epithelial Organ Culture Model Stem Cells, November 1, 1999; 17(6): 327 - 338. [Abstract] [Full Text]