Antibodies to Acholeplasma laidlawii membrane lipids in normal guinea pig serum

I Dörner, H Brunner, H G Schiefer, M Loos, H J Wellensiek
1977 Infection and Immunity  
Acholeplasma laidlawii is killed and lysed by fresh normal guinea pig serum (GPS) without additional antibodies. Prior incubation of GPS with whole A. laidlawii organisms abolishes the killing activity of GPS. In the present study it was demonstrated that antibodies are present in normal GPS. The classical pathway, not the alternative pathway, of the complement sequence was activated by these antibodies in fresh normal GPS. The antibodies in GPS belong to the IgG class of immunoglobulins. They
more » ... unoglobulins. They are directed predominantly against the membrane phospholipids ofA. laidlawii. These antibodies may be induced either by natural infection of guinea pigs with A. laidlawii or by antigenic determinants of other microorganisms or food antigens. In recent years it has been clearly demonstrated that some mycoplasmas are killed and lysed by the combined action of antibodies and complement (1, 6, 8, 12, 15, 20, 24, 25, 34) . Fresh normal guinea pig serum (GPS) has been most frequently used as the source of complement in these experiments. In studies on immune lysis of Mycoplasma pneumoniae it was noted that GPS by itself, without addition of antibodies, reduced the number of viable organisms. As had been reported by Gale and Kenny (15), Sethi and Teschner (34), and from our laboratory (8), removal of the growth-inhibitory substances from GPS by absorption with killed M. pneumoniae was not possible. Nevertheless, the possibility that small amounts of antibodies to M. pneumoniae, not detectable by our methods, were present in normal GPS could not be excluded. It has been recently shown by Bredt and Bitter-Suermann (4) that M. pneumoniae can activate the guinea pig complement system via the altemnative pathway. This activation results in rounding of the organisms. Efficient killing requires, in addition, the entire complement sequence. It was also shown that M. pneumoniae can interact directly with Cl in the absence of detectable amounts of antibodies (5). We have previously demonstrated that a decrease in viability of Acholeplasma laidlawii occurs when the organisms are incubated with fresh GPS (11). In this publication, data are pret Present address: sented indicating that antibodies of the immunoglobulin G (IgG) class can be detected in normal GPS. These antibodies are directed against the membrane lipids of the organisms and activate preferentially the classical pathway of complement. (These results were presented in a preliminary form at the Annual Meeting of the American Society for Microbiology, New York, 1975, and the Arbeitstagung der Deutschen Gesellschaft ftir Hygiene und Mikrobiologie, Mainz, West Germany, 1976). MATERIALS AND METHODS Organisms and growth media. A. laidlawii, oral strain, and M. pneumoniae, strain PI 1428, originally obtained from R. M. Chanock, Bethesda, Md., were used. A. laidlawii had been subcultured several times on artificial medium. M. pneumoniae was used in its sixth passage on growth medium (9, 11). The medium for A. laidlawii consisted of 350 ml of PPLO broth (Difco Laboratories, Detroit, Mich.) supplemented with 5 ml of PPLO serum fraction (Difco), 50 ml of 1% yeast extract (Oxoid Ltd., London), 10 ml of 50% glucose, 10 ml of 0.1% phenol red, 12.5 ml of 2% thallium acetate, and 1,000 U of penicillin G per ml. The pH was adjusted to 8.2 with 1 N sodium hydroxide. The growth medium for M. pneumoniae consisted of 350 ml of PPLO broth; 100 ml of agamma horse serum (Flow Laboratories, Inc., Rockville, Md.) that had been inactivated at 56°C for 30 min, 50 ml of 25% yeast extract (Flow), 10 ml of 50% glucose, 10 ml of 0.1% phenol red, 12.5 ml of 2% thallium acetate, and 1,000 U of penicillin G per ml. Culture conditions. For killing experiments, A. laidlawii was grown at 370C in screw-capped bottles containing 500 ml of broth medium and was harvested on May 9, 2020 by guest http://iai.asm.org/ Downloaded from
doi:10.1128/iai.18.1.1-7.1977 fatcat:h5sukqrasnbxrpxvhyhil3tpjm