Reference: Biol Bull. 167: 229-237. (August. 1984) INFLAMMATORY-LIKE REACTION IN THE TUNIC OF CIONA INTESTINALIS (TUNICATA). I. ENCAPSULATION AND TISSUE INJURY NICOLO PARRINELLO, ELEONORA PATRICOLO, AND CALOGERO CANICATTI Institute of Zoology, Palermo University. Via Archirafi, 18 90123 Palermo. Italy ABSTRACT Particulate (sheep erythrocytes, ascidian oocytes, stromata, colloidal carbon) or soluble agents (bovine serum albumin or hemoglobin, hemocyanin) were injected in varying doses into the tunic oiCiona intestinalis. This ascidian reacted by producing a capsule and/or tissue injury. Statistical analysis suggests that the two phenomena are independent, probably related to the nature and dose of the irritant. Light histological observations showed granulocyte degranulation in the damaged tissue, suggesting that an acute inflammatory-like process is involved in the tunic reaction. Introduction To maintain body integrity, tunicates have evolved mechanisms which destroy and eject foreign materials. The defense responses include both humoral and cellular components. They could constitute a surveillance system ancestral to the vertebrate immune system (Parrinello and Patricolo, 1975, 1984; Parrinelloe/a/., 1977;Parrinello and Canicatti, 1982, 1983; Wright and Ermak, 1982). Attempts to demonstrate immunological capabilities in the ascidian Ciona in-testinalis have shown that it possesses natural (non-inducible) bacteriocidins (Johnson and Chapman, 1970) and hemagglutinins (Parrinello and Patricolo, 1975; Wright and Cooper, 1975) and that it reacts by phagocytosis and encapsulation to foreign materials inserted into the tunic (Parrinello et ai, 1977), and rejects a first set of tunic allografts (Reddy et al, 1975). However the source of the natural defense responses needs further examination, while tunic graft rejection involves some persistent non-specific inflammatory responses. C intestinalis non-specifically reacts toward large concentrations of erythrocytes injected into the tunic and produces a capsule around them (Parrinello et ai, 1977). Cells infiltrate the area and release substances enveloping the foreign material. This response is often strong enough to produce large capsules visible through the tunic. Also in a variable number of treated specimens, the tunic matrix over the injected erythrocytes lysed, and a tunic wound was produced. Animals with the injured tunic survived for a period of time dependent on the seriousness of the trauma. In specimens which showed a slight reaction the wound healed. Preliminary light microscopic histological observations did not clarify the nature of such a reaction. Moreover, the data did not establish a relationship between the capsule and the injury. In this study the C. intestinalis tunic injury and encapsulation produced by various doses of particulate or soluble agents were investigated by examining their external Received 6 March 1984; accepted 29 May 1984. Abbreviations: SE = sheep erythrocytes; PBS = phosphate-buffered saline (0.01 A/ pH 7.4 phosphate buffer containing 0.15 M NaCl); BSA = bovine serum albumin; Hb = bovine hemoglobin; He = Octopus vulgaris hemocyanin. 229
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