HOST FACTORS AFFECTING RESPONSE TO THERAPY

  • Agarwal, Ram P, (PI)

Project: Research project

Description

Our in vitro investigations suggest that prolonged exposure of cells to AZT
increases thymidine kinase (TK) activity, the enzyme catalyzing the first
step in the sequential phosphorylation of AZT to its active metabolite,
AZT-5'-triphosphate (AZT-TP). Thus, TK activity is one of the major
determinants of AZT's chemotherapeutic response. Therefore, an important
question of clinical relevance is: Does the long term use of AZT also alter
lymphocytic TX activity in the patients who are on AZT therapy. Enhanced
phosphorylation of AZT or thymidine may yield high intracellular
concentrations of AZT-TP and/or thymidine-5'-triphosphate (TTP). Changes in
the intracellular AZT-TP and TTP may affect other intracellular nucleotide
pool, increase or reduce effectiveness or drug toxicity and require dose
adjustment. In order to examine some of these questions, we propose to
initiate the following pilot study: (i) to follow TK activity in the
lymphocytes of asymptomatic HIV seropositive patients who are on AZT at
entry and at 3, 6, and 9 months during therapy; and (ii) determine
intracellular accumulation of AZT-TP and TTP in the patients lymphocytes
and in H9 cells grown in vitro. Lymphocytes will be isolated from 15 ml
heparinized blood obtained from HIV seropositive asymptomatic patients who
are on AZT therapy (through an ongoing ACTG study at our institution). TK
will be assayed in the lysates of the cells and lymphocytes using
[methyl-3H] TdR or AZT. Incorporation of tritiated TdR or AZT in the
lymphocytic and H9 cellular nucleotide pool will be followed by HPLC. These
investigations will enhance our understanding on the effects of long term
use of AZT on its own efficacy and suggest strategies for needed
modifications in therapy.
StatusFinished
Effective start/end date9/30/909/29/92

Funding

  • National Institutes of Health

Fingerprint

Thymidine Kinase
HIV
Lymphocytes
Therapeutics
Drug-Related Side Effects and Adverse Reactions
Thymidine
Nucleotides
High Pressure Liquid Chromatography
Phosphorylation
3'-azido-3'-deoxythymidine 5'-triphosphate
Enzymes
thymidine 5'-triphosphate
In Vitro Techniques

ASJC

  • Medicine(all)
  • Immunology and Microbiology(all)