Local antibody production and immune complex formation in rats experimentally infected with Angiostrongylus cantonensis.

The systemic humoral immune responses and tissue localization of worm-antigen, antibodies (IgG), and complement (C3) were examined in rats experimentally infected with Angiostrongylus cantonensis. While the worms remained in the subarachnoid space, it was infiltrated with plasma cells and lymphoid cells containing IgM and IgG. When the infiltration of these cells became more pronounced, the serum antibody titer began to increase. At the same time, deposits of IgM, IgG, and C3 were found in the glomeruli of the kidney. A number of eggs were observed in the lungs, enclosed in granulomatous tissues. Infiltrates of plasma cells including IgM and IgG, and deposits of IgM, IgG, and C3 were detected around the eggs and in the granulomatous tissues. A marked increase in serum antibody was observed. A. cantonensis larvae induce local antibody (IgM and IgG) production in the central nervous system prior to an increase of serum antibody titer. Measurement of cerebrospinal fluid antibody titer at an early stage of infection may confirm infection. The larvae showed no evidence of damage in spite of marked local antibody production in the central nervous system. The eggs in the lungs stimulated both local and systemic antibody production, and immune complexes were formed in the lung and the circulatory system. Immune complexes may participate in the formation of granuloma.