大白鼠对伯氏疟原虫的易感性随鼠龄的增长而明显降低。以不同年龄组(30、50、100天)的鼠定量感染伯氏疟原虫,这3个年龄组的鼠在感染后48～72小时内原虫增殖率都是一致的,在这以后原虫增殖被抑制才与鼠龄不同有直接的关系。这说明老年鼠的血清中不存在有抗疟原虫的因素。再取不同年龄(30、50、90、100、300天)正常鼠的血清转科给幼年鼠(30天)并给予原虫感染,结果亦未能证明不同年龄鼠的正常血清中有抗疟原虫的因素,包括非抗体血清因素或交叉体液免疫。 Susceptibility of mice to P. berghei was significantly reduced with increasing age. Plasmodium berghei were infected with mice of different age groups (30, 50, 100 days). Protoplast proliferation rates of all three age groups were consistent within 48-72 hours after infection, after which protozoal proliferation was inhibited by Inhibition only with the different age have a direct relationship. This shows that there is no anti-malarial factor in the serum of the aged mice. Serum from normal mice of different ages (30, 50, 90, 100, 300 days) was also given to young mice (30 days) and infected with protozoa. The results also failed to prove that anti-malaria parasites Factors, including non-antibody serum factors or cross-humoral immunity.