IL-4 and IFN-γ mRNA induction in human peripheral lymphocytes specific for β-lactam antibiotics in immediate or delayed hypersensitivity reactions

beta-Lactam antibiotics elicit CD4+ and CD8+ T-cell-mediated immune responses that play a central role in allergic reactions. However, the involvement of a type 1- (Th1 or Tc1) or a type 2-like (Th2 or Tc2) differentiation in drug allergy remains unclear. We investigated the expression of interleukin 4 (IL-4) and interferon gamma (IFN-gamma) mRNA by quantitative reverse transcription and polymerase chain reaction (RT-PCR) in patient-derived peripheral blood lymphocytes following specific in vitro stimulation. Samples were collected from a total of 19 patients who had developed immediate or delayed clinical manifestations of hypersensitivity to beta-lactam and from 11 control subjects. peripheral blood mononuclear cells (PBMCs) were stimulated with either free antibiotics or antibiotic-human serum albumin (HSA) conjugates. Specific induction of IFN-gamma mRNA expression was observed in 11 of 11 allergic patients with immediate reactions, in 6 of 8 patients with delayed reactions, and in 4 of 11 control subjects. IL-4 mRNA expression was induced in 5 of 11 allergic individuals with immediate reactions but in none of the 8 patients with delayed responses and none of the 11 control subjects. IL-4 mRNA expression was only induced following activation with free drugs, while IFN-gamma mRNA expression was predominantly induced in CD4+ T cells following stimulation with HSA-conjugated drugs. Immediate-type hypersensitivity to beta-lactams was not associated with a pure type 2-like response when PBMCs were specifically stimulated in vitro: Some patients with well-documented history of beta-lactam-induced immediate allergic reaction showed a high IFN-gamma response. Contact dermatitis involved Tc1 and Th1 cells and other delayed hypersensitivity reactions to beta-lactams were restricted to Th1 responses.