植物血凝素(PHA)在体内能引起迟缓型变态反应。我们对121名健康儿童和成人进行了PHA皮试观察;对豚鼠作了组织学观察。方法是皮内注射67μg/0.1 ml,,分别于0.5、1、2、4、8、12和24小时测量红斑和硬结的直径。结果豚鼠皮试证明,4小时前以皮下水肿为主,8小时后以单核细胞浸润为主。1岁以上各年龄组健康人PHA皮试变异不大。PHA皮试动态观察证明,红斑和硬结直径有近似平行的关系,采用红斑直径作为判断标志。 Phytohemagglutinin (PHA) can cause delayed allergy in the body. We conducted a PHA skin test on 121 healthy children and adults; a histological observation of guinea pigs. The method was intradermal injection of 67μg / 0.1ml, respectively, at 0.5,1,2,4,8,12 and 24 hours to measure the diameter of erythema and induration. Results guinea pig skin test proved that 4 hours before the main subcutaneous edema, monocytes infiltration 8 hours after the main. PHA skin test for healthy people over the age of 1 year did not vary much. Dynamic observation of the PHA skin test proves that erythema and induration diameter are approximately parallel relationship, the use of erythema diameter as a judge sign.