Modulation of granulocyte responses in three-spined sticklebacks Gasterosteus aculeatus infected with the tapeworm Schistocephalus solidus

Diseases of Aquatic Organisms

M. Milinski¹  M. Kalbe¹  J. P. Scharsack¹  R. Derner¹  J. Kurtz¹ 

关键词: Gasterosteus aculeatus;    Schistocephalus solidus;    Granulocytes;    Reactive oxygen species;    Phagocytosis;   

DOI  :  10.3354/dao059141

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Leukocytes isolated from the head kidney and peripheral blood of 3-spined sticklebacks Gasterosteus aculeatus L. were analysed by means of flow cytometry during infection with the tapeworm Schistocephalus solidus (Müller, 1776).Although parasites increased their body weight continuously throughout the observation period (98 d), proportions of granulocytes increased in blood and head kidney only up to Day 63 post-infection (p.i.). Thereafter, declining proportions of granulocyteswere observed in both organs. Thus the relative decrease in granulocyte number was not correlated to a decline in the parasitic load of the fish. To investigate a possible modulatory impact of S. solidus on granulocyte function, head kidneyleukocytes were isolated at times before Day 63 p.i. and tested in vitro for their capacity to produce reactive oxygen species (ROS). Head kidney leukocytes from S. solidus-infected fish, analysed immediately after isolation (ex vivo,Day 40 p.i.), exhibited a higher ROS production when stimulated with phorbol myristate acetate (PMA), than leukocytes from naïve, sham-treated control fish and fish that had resisted or cleared the infection (exposed but not infected). The latter showedan increased spontaneous ROS production that was not correlated to the numbers of granulocytes present in the head kidney isolates. In infected sticklebacks, spontaneous and PMA-induced ROS production was significantly correlated with numbers ofgranulocytes present in the head kidney isolates, suggesting that elevated ROS production was due to higher numbers of responding cells rather than an increased capacity of single cells. In vitro, after cultivation for 4 d in the presence ofpokeweed mitogen (PWM) or extracts from S. solidus, head kidney leukocytes from control fish showed an increased ROS production and phagocytic activity compared with non-stimulated control cultures. In contrast, head kidney leukocytes from infectedfish isolated on Days 48 and 44 p.i., failed to respond to S. solidus antigens in vitro. During S. solidus infection, granulocyte mobilisation resulted in elevated numbers of these cells in head kidneys, but the lack of an invitro response to S. solidus antigens indicates an in vivo priming of granulocytes by the parasite. These observations may reflect the ability of S. solidus to impair the host¹s immune response once the parasite is developing inthe body cavity of G. aculeatus.

【 授权许可】

Unknown