Denis Maghil, Thayappan Karthigayani, Ramasamy Sivakumar Mullivanam, Munusamy Arumugam
Department of Zoology, University of Madras, Guindy Campus, Chennai, 600025 India.
Springerplus. 2015 Oct 13;4:601. doi: 10.1186/s40064-015-1349-0. eCollection 2015.
The sialic acid specific humoral lectin, Pjlec of the freshwater crab Paratelphusa jacquemontii was investigated for its opsonin function with rabbit erythrocyte as target cell for phagocytosis by the crab's hemocyte. The untreated or trypsin treated erythrocyte induced lectin response after challenge however failed when treated with neuraminidase evidently indicating glycan dependency for elicited immune response. Our observation of in vitro phagocytosis of the erythrocyte untreated or coated with serum, clarified serum appeared to be recognized and engulfed by hemocytes but when coated with isolated lectin Pjlec, the response was elicited. Moreover, with trypsin treated erythrocyte the response remained unchanged but neuraminidase or O-glycosidase treatment eliminated the response reaction. This suggested the sialic acid specific reaction of lectin with the erythrocyte and was essential for recognition to allow the lectin Pjlec to act as an opsonin. The flowcytometry observation affirmed the enhancement of phagocytosis by Pjlec coated hemocyte. The efficiency of in vitro hemolysis of Pjlec coated erythrocyte with hemocyte when compared to untreated erythrocyte with or without hemocyte also established the opsonic function of the lectin. The mechanism of phagocytosis and induction were dependent on specific recognition of the erythrocyte by the multivalent binding site of the lectin protein, and the elicitation of the immune response was a function of the sialoglycan surface. The pathway of the challenge suggested that after entry of nonself recognition by lectin was followed by induction and activation of phagocytosis by opsonic binding of the lectin.
以淡水蟹 Paratelphusa jacquemontii 的唾液酸特异性体液凝集素 Pjlec 为研究对象，以兔红细胞为靶细胞，研究其在蟹血细胞吞噬作用中的调理素功能。未处理或经胰蛋白酶处理的红细胞在受到刺激后会引发凝集素反应，但用神经氨酸酶处理后则失败，这明显表明引发免疫反应依赖聚糖。我们对未处理或包被血清的红细胞进行体外吞噬作用的观察表明，包被血清的红细胞似乎能被血细胞识别并吞噬，但用分离的凝集素 Pjlec 包被时，会引发反应。此外，用胰蛋白酶处理的红细胞反应不变，但用神经氨酸酶或 O - 糖苷酶处理则消除了反应。这表明凝集素与红细胞的唾液酸特异性反应，对于识别至关重要，从而使凝集素 Pjlec 能够作为调理素发挥作用。流式细胞术观察证实了包被 Pjlec 的血细胞增强了吞噬作用。与未处理的红细胞（有无血细胞）相比，用血细胞对包被 Pjlec 的红细胞进行体外溶血的效率也证实了凝集素的调理功能。吞噬作用和诱导机制依赖于凝集素蛋白多价结合位点对红细胞的特异性识别，免疫反应的引发是唾液酸聚糖表面的功能。刺激途径表明，凝集素识别非自身后，接着通过凝集素的调理结合诱导并激活吞噬作用。
