EFFECT OF BRUGIA-MALAYI INFECTIONS ON ENDOTHELIAL-CELLS - A MORPHOLOGICAL-STUDY

Athymic mice (C3H/HeN) parasitized by Brugia malayi develop gross lymp hatic dilations at the chronic stage of infection. The hyperplastic en dothelial cells and low fluid pressure of the lymphatics, characterist ic of these infections, suggest that abnormal changes in these cells m ay play an important role in the dilation. We studied the lymphatic an d vascular endothelium of parasitized mice for morphological changes b y scanning and/or transmission electron microscopy. The lymphatic endo thelium of dilated lymphatics was perturbed, scalloped, bulbous and hi ghly indented. Numerous mononuclear and giant cells were closely appos ed to the endothelial wall. Endothelial cells of both the lymphatics a nd the adjacent venules revealed no focal cytoplasmic lesions. Growth factor-dependent cell proliferation was significantly suppressed in vi tro in endothelial cell cultures containing adult female worms, male w orms or microfilariae. The actin cytoskeletal network appeared intact in these cells, and no gross changes in distribution were evident. Alt hough the lymphatic walls were highly tortuous, our examination reveal ed no significant alterations in their morphology. Perivascular infilt ration of activated mast cells, lymphocytes and monocytes/macrophages indicated polarization of inflammatory cells into the lymphatic tissue . It is possible that these inflammatory cells might induce temporal f unctional changes in the lymphatics of infected athymic mice.