Novel interferon-γ enzyme-linked immunoSpot assay using activated cells for identifying hypersensitivity-inducing drug culprits.

BACKGROUND

The drug-induced lymphocyte stimulation test (DLST), also referred to as lymphocyte transformation test (LTT), is used to identify the culprit drug in cases of cutaneous adverse drug reactions (cADR). Although DLST is a widely used in vitro test, its sensitivity and specificity are unsatisfactory. Recent reports suggest that the detection of drug-induced interferon (IFN)-γ production using enzyme-linked immunoSpot (ELISpot) assay (conventional IFN-γ ELISpot) is useful for identifying culprit drugs in cADR cases.

OBJECTIVE

The aim of this study was to establish a novel method for identifying culprit drugs in patients with cADR by efficiently detecting drug-specific IFN-γ production using activated cells.

METHODS

Sixteen patients with cADR, including drug-induced hypersensitivity syndrome, erythema multiforme-like eruption, maculopapular exanthema, Stevens-Johnson syndrome, and toxic epidermal necrolysis, caused by clinically convincing culprit drugs were enrolled in this study. In some cases, the blood samples were obtained at two or three different time points. Peripheral blood mononuclear cells (PBMCs) from total 20 samples were analyzed using both the DLST and drug-induced conventional IFN-γ ELISpot. In addition, drug-induced IFN-γ ELISpot was performed using PBMCs, which were stimulated with anti-cluster of differentiation (CD)-3/CD28 antibody-coated microbeads and interleukin (IL)-2 for 7 days before exposure to the culprit drugs (modified IFN-γ ELISpot).

RESULTS

Among the culprit drugs tested in each patient, the modified IFN-γ ELISpot was positive in 17 samples (13 patients) while DLST and conventional IFN-γ ELISpot were positive in eight and four samples (six and three patients), respectively.

CONCLUSION

The modified IFN-γ ELISpot using activated PBMCs was more sensitive than the conventional IFN-γ ELISpot was for detecting drug-induced IFN-γ production, which could be a useful in vitro tool for identifying culprit drugs in cADR cases.