FALCIPARUM-MALARIA IN NATURALLY INFECTED HUMAN PATIENTS - IV-ULTRASTRUCTURAL CHANGES IN PERIPHERAL WHITE BLOOD-CELLS

Ultrastructure of white blood cells (WBC) were studied in peripheral v enous blood from Saudi patients with acute falciparum malaria (AFM) an d compared with their counterparts in same patients 2 weeks after chlo roquine treatment and full recovery. A counting system was incorporate d to determine the rate of abnormal to normal cell type in plastic thi ck sections during the course of the disease. Neutrophilia, monocytosi s, eosinopenia and lymphocytosis were associated with various ultrastr uctural abnormalities including: (1) Knobby phagocytic polymorphnuclea r neutrophils (PMN) and promyelocytes, and PMN with highly vacuolated cytoplasm. (2) Irregularly outlined electron-dense nuclei in non-funct ional monocytes. (3) Unusual distribution of nuclear chromatin in rest ing B-lymphocytes, while others possess highly vacuolated cytoplasm an d knobby surfaces. (4) Absence of granules in granular lymphocytes con taining the known diagnostic paratubular crystalline arrays. (5) Plasm ablasts containing electron-dense granules and swollen mitochondria. T hese abnormalities were suggested to be due to the high level of paras itaemia producing some toxic soluble products. They may also be attrib uted to alteration of bone marrow macrophages as a sequence of their i nteraction with soluble parasite products or their phagocytic parasiti zed red cells and debris released during the rupture of schizonts. Thi s study showed that the number of abnormal WBC increases in patients w ith high level of parasitaemia; plasmablasts have the lowest rate of a bnormalities, while monocytes have the highest; old patients present w ith lower degree of parasitaemia than young patients due to a less mat ure immune system; and the AFM may have independent effects on the str ucture of human WBC.