HLAs: Key regulators of T-cell-mediated drug hypersensitivity

HLA. 2018 Jan;91(1):3-16. doi: 10.1111/tan.13183.


Adverse drug reactions (ADR) can be broadly categorised as either on-target or off-target. On-target ADRs arise as a direct consequence of the pharmacological properties of the drug and are therefore predictable and dose-dependent. On-target ADRs comprise the majority (>80%) of ADRs, relate to the drug's interaction with its known pharmacological target and are a result of a complex interplay of genetic and ecologic factors. In contrast, off-target ADRs, including immune-mediated ADRs (IM-ADRs), are due to unintended pharmacological interactions such as inadvertent ligation of host cell receptors or non-pharmacological interactions mediated through an adaptive immune response. IM-ADRs can be classified according to the primary immune cell involved and include B-cell-mediated (Gell-Coombs type I-III reactions) and T-cell-mediated (Gell-Coombs type IV or delayed hypersensitivity) reactions. IM-ADRs mediated by T cells are associated with phenotypically distinct clinical diagnoses and can vary from a mild delayed rash to a life-threatening cutaneous, systemic or organ disease, such as Stephen Johnson syndrome/toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms and drug-induced liver disease. T-cell-mediated ADRs are strongly linked to the carriage of particular HLA risk alleles which are in the case of abacavir hypersensitivity and HLA-B*57:01 has led to translation into the clinic as a routine screening test. In this review, we will discuss the immunogenetics and pathogenesis of IM-ADRs and how HLA associations inform both pre-drug screening strategies and mechanistic understanding.

Keywords: HLA; abacavir; adverse drug reaction; allopurinol; angioedema; aspirin exacerbated respiratory disease; carbamazepine; immunological memory; pharmacogenomics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • B-Lymphocytes / immunology*
  • B-Lymphocytes / pathology
  • Dideoxynucleosides / adverse effects*
  • Dideoxynucleosides / therapeutic use
  • Drug Hypersensitivity / genetics
  • Drug Hypersensitivity / immunology*
  • Drug Hypersensitivity / pathology
  • HLA-B Antigens / genetics
  • HLA-B Antigens / immunology*
  • Humans
  • Immunity, Cellular*
  • Risk Factors
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / pathology


  • Dideoxynucleosides
  • HLA-B Antigens
  • HLA-B*57:01 antigen
  • abacavir