T-cell involvement in delayed-type hypersensitivity reactions to infliximab

Variable results have been reported for patch testing with infliximab,4,5 with some authors describing a strong inhibitory effect of this drug on delayed skin-test responses, similar to the situation with glucocorticoids.5 Nevertheless, the presence of skin-test negativity does not rule out the diagnosis of a DTH reaction, as has been described with betalactams, where DPT is needed to establish the diagnosis.9 Although DTH reactions to drugs have been shown to be induced by a T-cell-dependent mechanism,10 in the case of biological agents, such as anti-TNFα, T-cell involvement has been demonstrated only in injection-site reactions induced by etanercept, with a superficial perivascular lymphocytic infiltrate mainly composed of CD8+ T cells, with few eosinophils,6 which is the same pattern as we detected in our study.