Here’s a description for a WordPress post tag titled “免疫細胞” in Traditional Chinese, suitable for blog posts about health and biology:

**Option 1: Concise and Informative**

免疫系統是身體的守護者，由「免疫細胞」構成，負責抵抗外來入侵者如細菌、病毒等，維護健康。

* **(Translation):** The immune system is the body’s guardian. It is composed of “immune cells,” which are responsible for fighting off foreign invaders such as bacteria and viruses, and maintaining health.

**Option 2: Slightly More Detailed**

深入探討人體的「免疫細胞」，包括T細胞、B細胞、巨噬細胞等，它們如何在免疫反應中協同合作，保護我們免受疾病的侵害。了解這些細胞的功能，有助於我們更好地維護免疫系統，保持健康狀態。

* **(Translation):** Deep dive into the body’s “immune cells,” including T cells, B cells, macrophages, etc. They work together in immune responses, protecting us from illnesses. Understanding the function of these cells helps us better maintain our immune system and stay healthy.

**Option 3: Focusing on Action (Call to Action)**

想要了解如何增強你的「免疫細胞」活力，提升抵抗力？本標籤下的文章將分享與免疫細胞相關的知識，包括食物、生活方式等，助您改善健康，減少生病風險。

* **(Translation):** Want to learn how to boost the vitality of your “immune cells” and enhance your resistance? Articles under this tag will share knowledge related to immune cells, including foods, lifestyles, etc., to help you improve your health and reduce the risk of getting sick.

**Key Considerations for Choosing the Best Description:**

* **Target Audience:** Consider who you are writing for. If it’s primarily for medical professionals, a more technical description might be appropriate. For the general public, use simpler language.
* **Post Content:** Tailor the description to the type of posts tagged with “免疫細胞.” If the posts primarily discuss types of cells, use option 2. If the posts focus on lifestyle and diet, use option 3.
* **WordPress Theme/Layout:** The character limit for the excerpt field in your WordPress theme will influence the ultimate choice. Aim for a length that won’t get cut off.
* **Keywords:** While the tag is the keyword, you can subtly incorporate relevant keywords like “免疫系統” (immune system), “健康” (health), “疾病” (illness) or specifics like “T細胞” (T cells) and “細菌” (bacteria) to aid searchability.

Remember to choose the description that best fits your blog’s overall tone and the related content. When entering this in WordPress, you won’t enter a *tag* description, just the *tag* itself (免疫細胞). The description should be added in the *excerpt* box when creating tags/categories. Most themes show the descriptions when a user hovers or clicks on the tag.