What is “biologic” agent?
Whole immune system suppression will cause serious side effects. Therefore “biologic” agents are developed to target partial immune systems for a variety of immune-mediated skin disorders, including psoriasis, atopic dermatitis, hidradenitis suppurativa, pemphigus vulgaris, urticaria, and cutaneous B-cell lymphomas as well as the cutaneous manifestations of systemic conditions such as Crohn disease, sarcoidosis, and vasculitis.
Tumor Necrosis Factor TNF
Tumour Necrosis Factor is a protein produced by macrophages/monocytes and T lymphocytes . The human TNFα are located on chromosome 6p21.33. Plasma TNF Normal value < or = 2.8 pg/mL, Serum TNF-alpha normal value < or = 5.6 pg/mL 
The macrophages/monocytes and T lymphotcytes are kinds of immune system white blood cells, they locate and ‘eat’ harmful particles such as bacteria, viruses, fungi, and parasites.
TNF (normal value) regulate a wide spectrum of biological processes including cell proliferation, differentiation, apoptosis, lipid metabolism, and coagulation[3,4]. It may boost a person’s immune response, and also may cause necrosis (cell death) of some types of tumor cells .
Depleted TNF (below normal value) may induce tuberculosis infection, bacterial infection, virus infections, breast cancer, lung cancer, lymphoma, and skin cancer [1,4].
Elevated TNF (above normal value) may induce psoriasis, rheumatoid arthritis (RA), inflammatory bowel diseases including Crohn’s disease and ulcerative colitis, multiple sclerosis, systemic lupus erythematosus and systemic sclerosis [1,4].
Tumor Necrosis Factor Inhibitor
The FDA has approved multiple tumor necrosis factor (TNF; previously known as TNF-α) inhibitors: etanercept (Enbrel ® ), etanerceptszzs (ErelziTM ), infliximab (Remicade ® ), infliximab-dyyb (Inflectra ® ), adalimumab (Humira ® ), adalimumab-atto (Amjevita ® ), golimumab (Simponi ® ), and certolizumab pegol (Cimzia ® ) .
US Food and Drug Administration (FDA) warnings and precautions for targeted immune modulators with dermatologic indications. Live vaccines should not be given to patients receiving these medications. BCG, bacillus Calmette–Guérin; IL, interleukin; LE, lupus erythematosus; TNF, tumor necrosis factor .
Nomenclature for monoclonal antibodies and fusion proteins. For example, ada-lim-u-mab, inf-li-xi-mab and certo-li-zu-mab pegol are immunomodulating immunoglobulins that are human, chimeric and humanized, respectively .
- Mayo Clinic Laboratory. https://www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/63022
- tumor necrosis factor [Homo sapiens (human)] Gene ID: 7124, updated on 11-Nov-2019. https://www.ncbi.nlm.nih.gov/gene/7124
- Tumor necrosis factor (TNF) Gene 19116 Online Mendelian Inheritance in Man. https://omim.org/entry/191160
- Definition of tumor necrosis factor. National Cancer Institue. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/tumor-necrosis-factor
- Jean L. Bolognia , Julie V. Schaffer , Lorenzo Cerroni, edit. Dermatology, Fourth edition, China: Elsevier, 2018, ISBN 978–0‐7020–6275–9. page2244-2250