Abstract:
Cytotoxic T lymphocyte (CTL) activity, as an important defence mechanism
against HIV-1 infection, was determined in 30 HIV-1 infected Thais who had a CD4 count in
the range of 5-1,420 cells/ml and with a viral load in the range of <400-246,000 copies/ml.
CTL assay was performed in bulk culture with in vitro stimulation of CTL precursors.
HIV/vaccinia recombinant-infected autologous peripheral blood mononuclear cells were used
as stimulators for in vitro expansion of the specific T cell clones. Autologous EBV
transformed B cells infected with recombinant viruses and labeled with 51Cr were used as
target cells. The HIV/ vaccinia recombinants used in the experiments were vT 142 (A/gag)
and vT 143 (A/pol) kindly provided by the NIH AIDS Research and Reference Reagent
Program; and vP1170 (wild type vaccinia); and vP1536 (E/env) kindly provided by
Virogenetics Corporation. HIV-1 viral load was determined by Roche/Amplicor HIV-1
MonitorTM test kit version 1.5. HIV-1 subtyping was performed by a V3 peptide ELISA.
Subtype classification revealed 29 cases of HIV-1 subtype E and 1 case of subtype B. This
study demonstrated the specific CTL activity to Gag, Env and Pol epitopes in 66.7, 63.3, and
16.7 % of subjects respectively. CTL activity was present even in subjects who had CD4 cell
counts lower than 200 cell/ml. Among four of them, one case had CTL activity to all three
HIV epitopes; and the other two had CTL activity against both Gag and Env epitopes.
Regarding cross clade activity, one case of subtype B infection had CTL activity to A/gag, but
not to other epitopes. Inverse correlation between the level of viral load and CD4 T cell
counts was shown (Pearson, r = -0.55, p= 0.002), while no correlation was observed between
the level of viral load or the level of CD8 T cell counts and values of CTL specific lysis; and
also there was no correlation between CD4 count level and percentages of CTL specific lysis
in any HIV epitopes analysed. A follow-up study of the subjects at every 3-6 months for one
year did not show any significant change in CTL activity.