免疫类别的一种方法是非特异性和特异性。非特异性防御 – 这些防御措施可以对抗所有异物和病原体。实例包括物理屏障，例如粘液，鼻毛，睫毛和纤毛。化学屏障也是一种非特异性防御。化学屏障包括皮肤和胃液的低pH值，泪液中的溶菌酶，阴道的碱性环境和耳垢。特殊防御 – 这种防御系统可以抵御特定的威胁，例如特定的细菌，病毒，朊病毒和霉菌。针对一种病原体起作用的特定防御通常不会对另一种病原体起作用。特定免疫力的一个例子是来自暴露或疫苗的抗性水痘。自然活动免疫力的一个例子是抵御感冒。人工主动免疫的一个例子是由于免疫而建立对疾病的抵抗力。过敏反应是对抗原的极端反应，这是由主动免疫引起的。获得性免疫 – 获得性或适应性免疫是身体的第三道防线。这是针对特定类型病原体的保护。获得性免疫可以是天然的或人为的。天然和人工免疫都具有被动和有源部件。主动免疫是由感染或免疫引起的，而被动免疫来自天然或人工获得抗体。先天免疫 – 一种遗传或基于遗传易感性的天然免疫。这种免疫力可以防止从出生到死亡。先天免疫包括外部防御（第一道防线）和内部防御（第二道防线）。内部防御包括发烧，补体系统，自然杀伤（NK）细胞，炎症，吞噬细胞和干扰素。先天免疫也被称为遗传免疫或家族免疫。活动免疫力来自暴露于病原体。病原体表面上的表面标志物充当抗原，其是抗体的结合位点。抗体是Y形蛋白质分子，它们可以单独存在或附着在特殊细胞的膜上。身体不会随时存放抗体以立即感染。称为克隆选择和扩增的过程会产生足够的抗体。主动免疫需要暴露于病原体或病原体的抗原。暴露于抗原导致抗体的产生。抗体基本上标记细胞被称为淋巴细胞的特殊血细胞破坏。参与主动免疫的细胞是T细胞（细胞毒性T细胞，辅助T细胞，记忆T细胞和抑制性T细胞），B细胞（记忆B细胞和浆细胞）和抗原呈递细胞（B细胞，树突细胞，和巨噬细胞）。在接触抗原和获得免疫力之间存在延迟。第一次暴露会导致所谓的主要反应。如果一个人以后再次暴露于病原体，则反应更快更强。这称为次要响应。主动免疫持续很长时间。它可以忍受多年或整个生命。主动免疫的副作用很少。它可能与自身免疫性疾病和过敏有关，但通常不会引起问题。
One way to categories immunity is as nonspecific and specific. Nonspecific Defenses – These defenses work against all foreign matter and pathogens. Examples include physical barriers, such as mucous, nasal hair, eyelashes, and cilia. Chemical barriers are also a type of nonspecific defense. Chemical barriers include the low pH of the skin and gastric juice, the enzyme lysozyme in tears, the alkaline environment of the vagina, and earwax. Specific Defenses – This line of defenses is active against particular threats, such as particular bacteria, viruses, prions, and mold. A specific defense that acts against one pathogen usually isn’t active against a different one. An example of specific immunity is resistance chicken pox either from exposure or a vaccine. An example of natural activity immunity is fighting off a cold. An example of artificial active immunity is building up a resistance to a disease due to an immunization. An allergic reaction is an extreme response to an antigen, resulting from active immunity. Acquired Immunity – Acquired or adaptive immunity is the body’s third line of defense. This is protection against specific types of pathogens. Acquired immunity may be either natural or artificial in nature. Both natural and artificial immunity have passive and active components. Active immunity results from an infection or an immunization, while passive immunity comes from naturally or artificially gaining antibodies. Innate Immunity – A type of natural immunity that is inherited or based on genetic predisposition. This type of immunity confers protection from birth until death. Innate immunity consists of external defenses (the first line of defense) and internal defenses (second line of defense). Internal defenses include fever, the complement system, natural killer (NK) cells, inflammation, phagocytes, and interferon. Innate immunity is also known as genetic immunity or familial immunity. Activity immunity comes from exposure to a pathogen. Surface markers on the pathogen surface act as antigens, which are binding sites for antibodies. Antibodies are Y-shaped protein molecules, which can exist on their own or attached to the membrane of special cells. The body doesn’t keep a store of antibodies on hand to take down an infection immediately. A process called clonal selection and expansion builds up sufficient antibodies. Active immunity requires exposure to a pathogen or to the antigen of a pathogen. Exposure to the antigen leads to the production of antibodies. Antibodies essentially mark a cell for destruction by special blood cells called lymphocytes. Cells involved in active immunity are T cells (cytotoxic T cells, helper T cells, memory T cells, and suppressor T cells), B cells (memory B cells and plasma cells), and antigen-presenting cells (B cells, dendritic cells, and macrophages). There is a delay between exposure to the antigen and acquiring immunity. The first exposure leads to what is called a primary response. If a person is exposed to the pathogen again later, the response is much faster and stronger. This is called a secondary response. Active immunity lasts a long time. It can endure for years or the entire life. There are few side effects of active immunity. It can be implicated in autoimmune diseases and allergies, but generally doesn’t cause problems.