Human thiopurine methyltransferase pharmacogenetics: effect of phenotype on sensitivity of cultured lymphocytes to 6-mercaptopurine
Thiopurine methyltransferase (EC 2.1.1.67, TPMT) catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine (6-MP). TPMT activity in human lymphocytes and other tissues is controlled by a common genetic polymorphism. These experiments were designed to study the relationship between TPMT phenotype and the effect of 6-MP on /sup 3/H-thymidine (/sup 3/H-TdR) incorporation into phytohemaglutinin (PHA) stimulated human peripheral blood lymphocytes. Lymphocytes were obtained from the blood of nine subjects, three subjects with each TPMT phenotype. 6-MP dose response curves were performed at optimal (10 ..mu..g/ml) and suboptimal (1 ..mu..g/ml) concentrations of PHA. ED50 values for 6-MP with lymphocytes from subjects who genetically lacked TPMT activity were higher than ED50 values for lymphocytes from subjects with genetically intermediate or high TPMT activity. However, ED50 values decreased as level of stimulation increased. Therefore, the effects of 6-MP were studied at a series of PHA concentrations that ranged from 0.1 ..mu..g/ml to 10 ..mu..g/ml. Lymphocytes from subjects who lacked TPMT activity had significantly higher K/sub ii/ values (1.37 +/- 0.340 ..mu..M; mean +/- SEM) for inhibition of /sup 3/H-TdR incorporation by 6-MP than did lymphocytes from subjects with intermediate or high TPMT activity (0.529 +/- 0.068 ..mu..M and 0.327 +/- 0.064 ..mu..M, respectively, P < .05 for both comparisons).
- Research Organization:
- Mayo Foundation, Rochester, MN
- OSTI ID:
- 6859466
- Report Number(s):
- CONF-8604222-; TRN: 87-010340
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:4; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
Similar Records
Structural Basis of Substrate Recognition in Thiopurine S-Methyltransferase
Human kidney thiopurine methyltransferase (TPMT): Photoaffinity labeling with ( sup 3 H-methyl)- S-adenosyl-L-methionine ( sup 3 H-ado-met)
Related Subjects
LYMPHOCYTES
SENSITIVITY
TRANSFERASES
BIOCHEMICAL REACTION KINETICS
ENZYME ACTIVITY
CELL CULTURES
DOSE-RESPONSE RELATIONSHIPS
MAN
PHENOTYPE
PHYTOHEMAGGLUTININ
THYMIDINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AGGLUTININS
ANIMAL CELLS
ANIMALS
ANTIBODIES
AZINES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBOHYDRATES
CONNECTIVE TISSUE CELLS
ENZYMES
HEMAGGLUTININS
HETEROCYCLIC COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LEUKOCYTES
MAMMALS
MATERIALS
MITOGENS
MUCOPROTEINS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
POLYSACCHARIDES
PRIMATES
PROTEINS
PYRIMIDINES
REACTION KINETICS
RIBOSIDES
SACCHARIDES
SOMATIC CELLS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques