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A 42-year-man complains of several months of weight loss, night sweats, mild sputumproduction, and the spitting up of blood. You run a PPD (tuberculin skin test) and theresults are positive. 29 amounts of IL-2, IFN-Y, andTNF. The immune cell responsible for Patients with tuberculus granulomas that have elevated this pattern of cytokine production is the : A. Cytotoxic T lymphocyte B. Epithelioid cell C. Lack cell D. TH1 cell E. TH2 cell

#ImD #Micro #L1 #L2 #L3 #Introduction #Immunity

👑 A lymphocyte population is isolated that: 🔹Does not require APCs 🔹Has no immunologic memory 🔹Is CD3 negative 🔹Kills through Fc receptor interaction 🔹Which receptor is MOST important for its cytotoxic mechanism? 🔹A) CD28 🔹B) CD16 🔹C) CD40 🔹D) CD21

👑 A patient develops overwhelming inflammation and hypotension after exposure to a bacterial exotoxin that activated a large population of T helper cells without antigen processing. Which cytokine is MOST directly responsible for the systemic toxic manifestations? 🔹A) IL-4 🔹B) IL-5 🔹C) TNF 🔹D) TGF-β

⭐️ T cells = 60–80% of total lymphocytes ⭐️ B cells = 15–35% of total lymphocytes ⭐️ CD4 → T helper cell (Th) CD8 → Cytotoxic T cell (Tc) CD25 → Treg marker CD3 → all T cells CD56 → NK cell marker CD16 → Fc receptor on NK cell (ADCC) CD19, CD20, CD21 → B cell markers CD28 → T-cell co-stimulation receptor ⭐️ Th1 cytokines = IL-2, IL-3, TNF, IFN-γ. Th2 cytokines = IL-4, IL-5, IL-6, IL-10, IL-13. Treg/Th3 cytokines = TGF-β and IL-10. IFN-γ activates macrophages and NK cells. IL-2 is the major T-cell growth factor. IL-4 is important for IgE class switching. IL-5 is associated with eosinophils. IL-10 is anti-inflammatory. IL-12 activates NK cells. TNF is heavily involved in toxic shock syndrome.

CD 19-20-21 Present only on B cells (markers) Function: signal transduction

CD3 (signal transduction) presents in ALL T lymphocytes (marker)

People with CD3 deficiency are immunocompromised & vaccines aren’t effective with them (no signal is transduced to activate)

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