title: Clinical, histological, and immunophenotypic characteristics of injection site reactions associated with etanercept: a recombinant tumor necrosis factor alpha receptor: Fc fusion protein.
abstract: OBJECTIVE
  To study injection site reactions (ISRs) associated with etanercept therapy.
  
  
  METHODS
  Retrospective chart review, along with prospective analysis of selected patients experiencing ISRs associated with etanercept therapy.
  
  
  METHODS
  Academic rheumatology/immunology unit and dermatology clinic.
  
  
  METHODS
  Patients with rheumatoid arthritis, juvenile rheumatoid arthritis, inflammatory seronegative arthritis, psoriatic arthritis, psoriasis, or inflammatory bowel disease.
  
  
  METHODS
  Skin biopsy specimens were taken from selected patients experiencing ISRs.
  
  
  METHODS
  Incidence of IRSs and histological and immunophenotypic analysis of ISRs in 3 patients undergoing prospective study.
  
  
  RESULTS
  Twenty-one (20%) of 103 of all patients receiving etanercept reported ISRs, all within the first 2 months of inception of therapy. The reactions occurred 1 to 2 days after the last injection and resolved within a few days. Moreover, eventual waning of reactions was observed, with none proving to be dose limiting. Histological examination of all biopsy specimens showed an inflammatory infiltrate composed of predominantly lymphoid cells and some eosinophils, in a perivascular cuffing pattern, without evidence of leukocytoclastic vasculitis. The infiltrating lymphoid cells were predominantly activated mature (HLA-DR(+)/CD3(+)/CD4(-)/CD8(+)) cytotoxic T lymphocytes, with a small number of CD4(+) cells. A biopsy specimen from a recall ISR showed strong HLA-DR expression by epidermal keratinocytes.
  
  
  CONCLUSIONS
  Injection site reactions associated with etanercept therapy are common, and may be an example of a T-lymphocyte-mediated delayed-type hypersensitivity reaction, with waning over time due to eventual induction of tolerance.
authors.affiliation: University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: R
authors.initials: R
authors.lastname: Zeltser
authors.forename: L
authors.initials: L
authors.lastname: Valle
authors.forename: C
authors.initials: C
authors.lastname: Tanck
authors.forename: M M
authors.initials: MM
authors.lastname: Holyst
authors.forename: C
authors.initials: C
authors.lastname: Ritchlin
authors.forename: A A
authors.initials: AA
authors.lastname: Gaspari
mesh_terms: D018501:Antirheumatic Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000188:drug therapy*; D001706:Biopsy; D004342:Drug Hypersensitivity / Q000453:epidemiology* / Q000276:immunology / Q000473:pathology; D000068800:Etanercept; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000139:chemically induced* / Q000175:diagnosis / Q000473:pathology; D007108:Immune Tolerance / Q000187:drug effects; D007074:Immunoglobulin G / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology; D007150:Immunohistochemistry; D016130:Immunophenotyping; D015994:Incidence; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000188:drug therapy; D007279:Injections, Subcutaneous / Q000009:adverse effects; D015603:Keratinocytes / Q000378:metabolism / Q000473:pathology; D011565:Psoriasis / Q000150:complications / Q000188:drug therapy; D018124:Receptors, Tumor Necrosis Factor / Q000008:administration & dosage / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000009:adverse effects; D012189:Retrospective Studies; D012867:Skin / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D018501:Antirheumatic Agents; D000949:Histocompatibility Antigens Class II; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D011993:Recombinant Fusion Proteins; D000068800:Etanercept