Immune System — Key English Terminology

1.Innate immunity is fast (minutes to hours), nonspecific, has no memory. Components: skin barriers, mucosa, phagocytes, NK cells, complement, inflammation. Receptors: pattern recognition receptors PRRs, like TLR.

先天免疫快速（數分鐘到數小時），非特異性，無記憶。成分：皮膚屏障、黏膜、吞噬細胞、NK 細胞、補體、發炎反應。受體：模式識別受體 PRRs，如 TLR。

2.Adaptive immunity is slow (days), highly specific, has memory cells. Components: T cells, B cells, antibodies. Receptors: B cell receptor BCR and T cell receptor TCR.

適應性免疫較慢（數天），高度特異性，有記憶細胞。成分：T 細胞、B 細胞、抗體。受體：B 細胞受體 BCR 和 T 細胞受體 TCR。

3.Helper T cell, T-helper, marker CD4: secretes cytokines to activate other immune cells. Without CD4 helpers, B cells cannot do class switching and cytotoxic T cells are not fully activated. HIV attacks CD4 T cells leading to AIDS.

輔助 T 細胞，標記 CD4：分泌細胞激素活化其他免疫細胞。沒有 CD4，B 細胞無法做類別轉換，毒殺 T 細胞活化不完全。HIV 攻擊 CD4 T 細胞導致 AIDS。

4.Cytotoxic T cell, T-cytotoxic, marker CD8: directly kills infected cells using perforin and granzyme. Regulatory T cell, marker CD4 plus CD25: suppresses immune response and prevents autoimmunity. Memory T cell: faster and stronger secondary response.

毒殺 T 細胞，標記 CD8：以穿孔素和顆粒酶直接殺死被感染的細胞。調節 T 細胞，標記 CD4 加 CD25：抑制免疫反應、防止自體免疫。記憶 T 細胞：二次反應更快更強。

5.IgG: monomer, most abundant — about seventy-five percent. Only Ig that crosses the placenta. Functions: neutralization, opsonization, complement activation. Mnemonic: G equals greatest amount.

IgG：單體，最多約 75%。唯一能穿過胎盤的 Ig。功能：中和、調理、活化補體。口訣：G = Greatest amount。

6.IgA: dimer, about fifteen percent. Mucosal immunity — saliva, breast milk, intestinal secretions. Mnemonic: A equals mucosal Area.

IgA：二聚體，約 15%。黏膜免疫——唾液、母乳、腸道分泌物。口訣：A = mucosal Area。

7.IgM: pentamer, about ten percent. First to appear in primary immune response; strongest complement activation. Mnemonic: M equals first Made.

IgM：五聚體，約 10%。初次免疫反應最先出現；活化補體最強。口訣：M = first Made。

8.IgE: trace amount. Allergic reactions via mast cell degranulation; also anti-parasitic. IgD: trace, B cell surface receptor; function not fully understood.

IgE：極微量。過敏反應（肥大細胞脫顆粒）；抗寄生蟲。IgD：極微量，B 細胞表面受體；功能不完全清楚。

9.Year one fourteen exam point: after vaccination, primary response mainly produces IgM, secondary booster response mainly produces IgG — abundant, high affinity, long-lasting.

114 年考點：接種疫苗後，初次反應主要產生 IgM，二次 booster 反應主要產生 IgG——量多、親和力高、持續時間長。

10.Clonal selection theory four steps: One, diversity generation via V(D)J recombination — each B and T cell has a unique receptor. Two, antigen selection — antigen binds the best-matching receptor. Three, clonal expansion — selected cells proliferate. Four, effector and memory differentiation.

克隆選擇學說四步驟：一、多樣性產生，經由 VDJ 重組——每個 B 和 T 細胞有獨特受體。二、抗原選擇——抗原與最匹配的受體結合。三、克隆擴增——被選中的細胞大量增殖。四、效應與記憶分化。

11.Core concept: the immune system does NOT create matching receptors upon encountering antigen. Instead, millions of receptors already exist in advance — one per lymphocyte — and antigen merely SELECTS and expands the matching clone.

核心概念：免疫系統不是「遇到抗原才造受體」，而是預先就有數百萬種不同受體（每個淋巴球一種），抗原只是「選擇」並擴增剛好能結合的克隆。

12.Active natural: recovery after infection — memory cells, long-lasting. Active artificial: vaccination — memory cells, long-lasting. Passive natural: maternal IgG crossing the placenta — no memory, temporary. Passive artificial: antibody injection or antiserum — no memory, temporary.

主動自然：感染後康復——記憶細胞，持久。主動人工：疫苗接種——記憶細胞，持久。被動自然：母體 IgG 通過胎盤——無記憶，暫時。被動人工：注射抗體（antiserum）——無記憶，暫時。