P013 <i>In vitro</i> detection of the suspected drug in maculopapular drug reaction to antibiotics using secreted cytokines from drug-specific activated T cells

Abstract Maculopapular drug eruptions to antibiotics are associated with enhanced expression of T helper cell (Th)1 cytokines like interferon (IFN)-γ or Th2 cytokines like interleukin (IL)-5. Identifying the culprit drug usually involves rechallenge, which may not be forthcoming. Memory lymphocytes remain responsive to the culprit drug long after the reaction has resolved. Upon reactivation in vitro, there is increased proliferation and expression of certain markers, which provides us with an opportunity to predict the causal drug. This study aimed to assess drug-specific cytokine production (IL-5 and IFN-γ) in peripheral blood mononuclear cell culture supernatants to predict the causal antibiotic in maculopapular drug eruptions. Peripheral blood mononuclear cells of 20 patients who developed maculopapular drug eruptions to various antibiotics and 11 drug-matched healthy controls were incubated for 5 days with the respective drugs at two different concentrations. Cytokines secreted were measured in the supernatants at 6 h, day 2 and day 5 using enzyme-linked immunosorbent assay (ELISA) for IL-5 and IFN-γ. Drug-specific IL-5 and IFN-γ production was seen in 65% and 74% of the cases, respectively. Maximal secretion levels of IL-5 and IFN-γ were observed on day 5 and day 2 of incubation, respectively. The cutoff delta values, which are the difference in cytokine concentration of the drug-stimulated and unstimulated samples, were 4 pg mL−1 and 6 pg mL−1 for IL-5 and IFN-γ, respectively. In conclusion, the measurement of drug-specific secretion of IL-5 and IFN-γ using ELISA is a valuable method for detection of antibiotic-­induced maculopapular exanthema.