机体的免疫系统可能是除神经系统以外最为复杂的一个系统。它能以一种特异的方式对外界环境中大量的各种抗原作出相应的反应。免疫系统主要由淋巴细胞、巨噬细胞及多种可溶性介质,例如免疫球蛋白、淋巴因子及补体等所组成。近年来对巨噬细胞的作用有较多新见解。许多抗原必须经过巨噬细胞的“提呈作用”,T细胞才能发生细胞免疫反应或进而激发B细胞产生体液免疫反应。本文主要介绍在这一复杂的免疫反应中主要组织相容性系统(Major Histocompatibllity System,MHS)发挥着怎样的 The body’s immune system may be the most complicated except for the nervous system. It responds to a wide variety of antigens in the environment in a specific way. The immune system is mainly composed of lymphocytes, macrophages and a variety of soluble media such as immunoglobulins, lymphokines and complement. In recent years the role of macrophages have more new insights. Many antigens must be “presented” by macrophages, and T cells can undergo cellular immune responses or, in turn, stimulate B cells to produce humoral immune responses. This article describes how a Major Histocompatibility System (MHS) plays a role in this complex immune response