Isolation and Characterization of Antibodies from Sera of Humans Infected with Echinococcus granulosus

Abstract

Antibodies were isolated from sera of patients with hydatidosis using an immunoadsorbent prepared by cross-linkage of sheep hydatid fluid with glutaraldehyde. The antibodies eluted consisted mainly of IgG but IgA and IgM were also detected. In sera from patients with echinococcosis, antibodies directed against antigens present in the hydatid fluid can be detected by serological techniques such as indirect hemagglutination (IHA), latex flocculation, bentonite flocculation, complement fixation, and skin sensitivity tests. For review see Kagan (1968). Kagan et al. (1968) demonstrated serological activity in the IgG fraction of a patient's serum. Castagnari et al. (1968) found an increase in IgG and IgA levels both in patients who had undergone surgery several years before, and in recently diagnosed cases. They found serological activity in IHA to reside in the IgG and IgM fractions, though at a much lower level in the latter. Melli et al. (1966) were able to detect reaginic activity in a fraction containing IgA and free from IgM and IgG. Nevertheless, absorption with rabbit antiIgA did not remove the reaginic activity, suggesting the presence of a further type of immunoglobulin possibly similar to that found by Ishizaka, Ishizaka, and Lee (1966) in the sera of atopic patients (IgE). It is clear from these studies that infection with Echinococcus cysts results in the formation of circulating antibodies belonging to several immunoglobulin classes. This paper describes an attempt to isolate such antibodies by an immunospecific method. MATERIALS AND METHODS Sheep hydatid fluid (SHF) A pool of hydatid fluid from liver cysts in infected sheep was used throughout this study. Merthiolate 1/10,000 was added as a preservative and the fluid was stored at -20 C. It was concentrated either by lyophilization or dialysis against Carbowax 20.000 (Union Carbide, USA). Received for publication 18 September 1969. Sera from patients with hydatid cysts P-1 and P-2 were pools from 8 and 7 patients, respectively, whose IHA titers varied from 1/200 to 1/40,000. All these patients had been receiving "biological treatment" at the Hospital Alvarez, Buenos Aires, Argentina. This treatment consists of a course of immunization against Echinococcus granulosus antigens administered intradermally and/or subcutaneously. The antigen employed is a mixture of germinative membrane and hydatid fluid, in the proportion of 100 g of wet membrane to 4 to 6 liters of hydatid fluid of both ovine and bovine origin. Some patients had been under this treatment for a period of more than 10 years. Pool P-3 was from 5 untreated hydatidosis patients. Pools of normal human serum (NS-1 and NS-2) were acquired from persons clinically and serologically free from hydatid disease. All sera were delipidized prior to use by centrifugation followed by filtration at 4 C.