|
||
J. Exp. Med.,
Volume 188, Number 10, November 16, 1998 1785-1793
By

From the * Molecular Immunology Group, Nuffield Department of Clinical Medicine, University of
Oxford, Oxford OX3 9DU, United Kingdom; and the Effective long-term antiviral immunity requires specific cytotoxic T lymphocytes and CD4+ T
lymphocyte help. Failure of these helper responses can be a principle cause of viral persistence.
We sought evidence that variation in HIV-1 CD4+ T helper epitopes might contribute to this
phenomenon. To determine this, we assayed fresh peripheral blood mononuclear cells from 43 asymptomatic HIV-1+ patients for proliferative responses to HIV-1 antigens. 12 (28%) showed
a positive response, and we went on to map dominant epitopes in two individuals, to p24 Gag
restricted by human histocompatibility leukocyte antigen (HLA)-DR1 and to p17 Gag restricted by HLA-DRB52c. Nine naturally occurring variants of the p24 Gag epitope were found in the proviral DNA of the individual in whom this response was detected. All variants
bound to HLA-DR1, but three of these peptides failed to stimulate a CD4+ T lymphocyte line
which recognized the index sequence. Antigenic variation was also detected in the p17 Gag
epitope; a dominant viral variant present in the patient was well recognized by a specific CD4+
T lymphocyte line, whereas several natural mutants were not. Importantly, variants detected at
both epitopes also failed to stimulate fresh uncultured cells while index peptide stimulated successfully. These results demonstrate that variant antigens arise in HIV-1+ patients which fail to
stimulate the T cell antigen receptor of HLA class II-restricted lymphocytes, although the peptide epitopes are capable of being presented on the cell surface. In HIV-1 infection, naturally
occurring HLA class II-restricted altered peptide ligands that fail to stimulate the circulating T
lymphocyte repertoire may curtail helper responses at sites where variant viruses predominate.
Department of Genito-Urinary Medicine,
Radcliffe Infirmary, Oxford OX2 6HW, United Kingdom
This article has been cited by other articles:
| TABLE OF CONTENTS |
|