Immunomodulation of perioval
granulomas is a well-known phenomenon in schistosome-infected mice, but only little is known about
granuloma modulation in other animal models of human
schistosomiasis. In the present study, we explored
immunomodulation of egg
granulomas in the liver in a pig model of
schistosomiasis japonica.
Granuloma size was measured and T cells, B cells and
IgG(+) plasma cells in
granulomas were quantified in pigs at 9, 12 and 21 weeks post
infection (wpi) with Schistosoma japonicum.
Granulomas were largest at 9 wpi, had decreased significantly in size at 12 wpi and remained small at 21 wpi (9 vs. 12 and 21 wpi: P < 0.05). The size of
granulomas containing mature and immature eggs, respectively, did not differ significantly. The density of T (CD3epsilon(+)) cells and
IgG(+) plasma cells in
granulomas was the same, irrespective of
granuloma size and time points. B (CD79alpha(+)) cells were rare in
granulomas. The results indicate that in pigs, S. japonicum egg
granulomas in the liver are immunomodulated at an early stage of
infection, and that not only mature but also immature eggs induce a marked granulomatous reaction in this species.