A novel lymphocyte toxicity assay to assess drug hypersensitivity syndromes.
OBJECTIVE
To validate the novel lymphocyte toxicity assay (LTA) based on the mitochondrial succinate dehydrogenase (SDH) activity vs. the LTA by using trypan blue exclusion and to determine the utility of the assay to confirm drug hypersensitivity syndrome (DHS) to sulphonamides (SMX) and aromatic anticonvulsants.


METHODS
Incubation of patient lymphocytes, with or without murine hepatic microsomes with anticonvulsants or SMX. The viability of lymphocytes was based on SDH activity that can be measured spectrophotometrically. The percentage of cells displaying cytotoxicity compared to controls (cells treated only with drug) was calculated. Seventy-two immunocompetent and 16 immunocompromised (HIV) patients with DHS to SMX were sampled. The results were validated vs. 26 controls that had not experienced DHS to SMX. Sixty-two patients who had DHS to anticonvulsants were compared with 24 controls that did not have any DHS to the same anticonvulsants.


RESULTS
The results showed a very good percentage of sensitivity 98 and specificity 96 with a kappa-score of 0.96. LTA higher than 13.5% was considered positive for the immunocompetent population and LTA higher than 22% was positive for the immunocompromised population. In two of the 26 controls, LTA was positive.


CONCLUSIONS
The high quantitative kappa-value 0.96 emphasizes that the novel LTA is at least as good as the trypan blue assay. The latter is labor intensive, time consuming, and prone to human error. The new assay is objective, faster, and has been reproducible in assessing cytotoxicity.
Neuman
M G
MG
Division of Clinical Pharmacology, Sunnybrook & Women's College Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada. manuela@sten.sunnybrok.utoronto.ca
Malkiewicz
I M
IM
Shear
N H
NH
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D002220:Carbamazepine / Q000494:pharmacology; D016022:Case-Control Studies; D002470:Cell Survival; D002624:Chemistry, Clinical / Q000379:methods*; D002648:Child; D015331:Cohort Studies; D004396:Coloring Agents / Q000494:pharmacology; D004342:Drug Hypersensitivity; D005192:Family Health; D005260:Female; D006679:HIV Seropositivity / Q000097:blood; D006801:Humans; D000077213:Lamotrigine; D008214:Lymphocytes / Q000187:drug effects*; D008297:Male; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology; D010634:Phenobarbital / Q000494:pharmacology; D010672:Phenytoin / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013411:Sulfadiazine / Q000494:pharmacology; D013420:Sulfamethoxazole / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D014227:Triazines / Q000494:pharmacology; D014295:Trimethoprim / Q000494:pharmacology; D014343:Trypan Blue / Q000494:pharmacology
D000927:Anticonvulsants; D004396:Coloring Agents; D013449:Sulfonamides; D013778:Tetrazolium Salts; D013844:Thiazoles; D014227:Triazines; D013411:Sulfadiazine; D002220:Carbamazepine; D010672:Phenytoin; D014295:Trimethoprim; D013385:Succinate Dehydrogenase; C022616:thiazolyl blue; D014343:Trypan Blue; D013420:Sulfamethoxazole; D000077213:Lamotrigine; D010634:Phenobarbital