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واحد يخاف يدز و يصير اضحية العيد

ادز لو ما الكم خلك وره العيد ؟

ان شاء الله كلكم تحصلون جلدية و اشعة و عيون

‏قال رسول الله ﷺ ‏خير الدعاء دعاء يوم عرفة ‏وخيرُ ما قلتُ أنا والنبيُّون مِن قبلي: ‏«لا إلهَ إلَّا اللهُ وحدَهُ لا شريكَ له، له الملكُ وله الحمدُ وهو على كلِّ شيءٍ قدير»

🚨 Natural Killer Cells innate cytotoxic lymphocytes Source: bone marrow precursors. 🔹10–15% of lymphocytes in peripheral blood. 🔹1–2% of lymphocytes in spleen. Function: cytotoxic for: 1️⃣Tumor cells — immune surveillance. 2️⃣Viral-infected cells. 3️⃣Bacterial, fungal, and parasitic infections. 🔹NK cells are responsible for antibody-dependent cell-mediated cytotoxicity — ADCC. 🔹They require antibody for ADCC activation. 🔹They have receptors for the Fc portion of antibody. 🔹They do not directly recognize antigen like T cells. 🔹They need antibodies coating the target cell to attack foreign bodies in ADCC. 🔹They have no memory.

🟰 CD8+ T-cell activation is supported by CD4+ T helper cells through cytokines such as IL-2.

مهم

🚨 MHC Class I vs MHC Class II 1️⃣ MHC Class II 🔹Recognized by: CD4+ T helper cells. 🔹Antigen type: exogenous antigen. 🔹Meaning: antigen comes from outside the cell. 🔹Examples: bacterial infection, extracellular microbes. 🔹Main idea: APC eats the antigen → processes it → presents it on MHC II → CD4+ T helper cell recognizes it. 📌 MCQ ALERT: -MHC II presents exogenous antigen to CD4+ T helper cells. 2️⃣ MHC Class I 🔹Recognized by: CD8+ cytotoxic T cells. 🔹Antigen type: endogenous antigen. 🔹Meaning: antigen comes from inside the cell. 🔹Examples: viral infection, intracellular infection, malignancy/tumor antigen. 🔹Main idea: infected or abnormal cell makes abnormal internal protein → presents it on MHC I → CD8+ cytotoxic T cell kills it. 📌 MCQ ALERT: -MHC I presents endogenous antigen to CD8+ cytotoxic T cells. 🔥 High-yield comparison: -MHC I → CD8 → endogenous → viral/tumor → killing. -MHC II → CD4 → exogenous → bacterial/extracellular → helper activation.

💎 APC activation occurs by: 1 Phagocytosis 2 Gamma-interferon / IFN-γ 3 Cytokines from T helper cells, especially IL-2 and IL-12 🔹IL-8 is chemotactic. Meaning: IL-8 attracts immune cells, especially neutrophils, to the site of infection/inflammation. 📌 MCQ ALERT: B7 on APC binds CD28 on T helper cells. MHC class II presents antigen to CD4+ T helper cells. IFN-γ activates macrophages.. 🔪 Killer memory: APC needs “B7 to shake CD28’s hand” and “MHC II to talk to CD4.”

💎 Mononuclear cells -Monocytes in blood -Macrophages in tissue -Histocytes in connective tissues -Kupffer in liver -Splenocytes in spleen -glail in brain

💎 -IFN-α = macrophages / virus-infected cells. -IFN-β = fibroblasts. -IFN-γ = T lymphocytes.

💎 IFN-Interferons activates all immune cells except B cells

👑 A 17-year-old student has recurrent episodes of meningitis. Laboratory testing shows normal immunoglobulin levels and normal neutrophil count, but defective membrane attack complex formation. Which organism is he most classically susceptible to? 🔹A) Streptococcus pneumoniae 🔹B) Staphylococcus aureus 🔹C) Candida albicans 🔹D) Neisseria meningitidis

👑 A child has recurrent bacterial infections and later develops features suggestive of SLE. Which complement deficiency best explains this presentation? 🔹A) C1 inhibitor deficiency 🔹B) C3 deficiency 🔹C) C9 deficiency 🔹D) Factor H excess

👑 Deficiency of Factor B or Factor D in the complement system predisposes mainly to which type of infection? 🔹A) Viral infections 🔹B) Pyogenic bacterial infections 🔹C) Fungal granulomatous infections 🔹D) Parasitic helminthic infections

👑 Deficiency of C1, C2, C3, or C4 predisposes to SLE mainly because complement normally helps in: 🔹A) Direct activation of IgE on mast cells 🔹B) Keeping immune complexes soluble and clearing them from tissues 🔹C) Killing virus-infected cells through perforin 🔹D) Maturation of T lymphocytes in the thymus