Autoimmunity in trypanosome infections. I. Tissue autoantibodies in Trypanosoma (Trypanozoon) brucei infections of the rabbit

Ten rabbits infected with Trypanosoma (Trypanozoon) brucei showed a substantial increase in a natural anti-tissue autoantibody and Wassermann antibody. Absorptions suggest that the liver and Wassermann antibodies are distinct. The liver antibody reacts equally well with homologous and autologous liver. Absorption with trypanosomes and liver show that cross-reacting trypanosomal antibodies are not responsible for the liver activity. These antibodies will contribute to the raised IgM levels of rabbit trypanosomiasis and may be important in this respect but the precise extent of the contribution is not known.

It is suggested that a depression of certain T-cell functions may release antibody secreting B-cell descendants from T-cell control resulting in elevated IgM.

Anti-cardiolipin and anti-phosphatidylglycerol antibodies prepared against bacterial phospholipids

Anti-phosphatidylglycerol and anti-cardiolipin antisera were prepared in rabbits by using phospholipids purified from Micrococcus lysodeikticus. Anti-phosphatidylglycerol antibodies were found in antisera when either phosphatidylglycerol or cardiolipin were used as immunogens, but adsorption studies indicated they were not similar. Antibodies which reacted with phosphatidylinositol and phosphatidic acid were also found in the anti-cardiolipin antiserum. Structures of the antigenic groups in phosphatidylglycerol and cardiolipin are suggested from cross-reaction and adsorption studies. Adsorption studies with pure phospholipid antigens indicated the importance of the spacial orientation of phospholipid haptens for immunological reactivity.

Structural characteristics of hydrated glycerol-and sphingo-lipids. A spin label study

(1) The structural organization and fluidity of a variety of lipid classes were studied by electron spin resonance spectroscopy of fully hydrated planar films labeled with 3-doxyl-cholestane and 5-doxyl-palmitate and of dispersions labeled with 5-doxyl-palmitate. The phase of each lipid was checked by use of a polarizing microscope.(2) Orientation in a lamellar phase was detected for phosphatidyl-choline, -ethanolamine, -inositol, phosphatidic acid, cardiolipin, ceramide, and sphingomyelin. In the presence of 33 or 50 mol % cholesterol, the orientation was improved in all of these lipids with the exception of cardiolipin and orientation was induced in phosphatidylserine, monoglycerides, sphingosine, and cerebrosides. Cholesterol fluidized the sphingolipids sufficiently to solubilize the spin labels and allow formation of oriented multibilayers by this method.(3) Anisotropic motion of 5-doxyl-palmitate was also seen in films and disperions of 1-monoglycerides and diglycerides and in dispersions of gangliosides, which are known to exist in hexagonal or micellar phases.(4) The contribution of the molecular structures to the stability of the lamellar phase is discussed.

Orientation and motion of amphiphilic spin labels in hexagonal lipid phases

The acyl chain of spin-labeled fatty acids intercalates between the lipid hydrocarbon chains in hexagonal and micellar phases with the carboxyl group anchored at the lipid water interface. The spectra are characteristic of anisotropic motion and cannot be distinguished from the spectra of these probes in lamellar dispersions. In the hexagonal and micellar phases the molecular motion of the spin label increases as it is moved further away from the carboxyl group, similar to the behavior in the lamellar phase (Jost et al. (1971) J. Mol. Biol. 59, 77-98). The similarity in packing of the acyl chains in the hexagonal and lamellar phases suggests that localized regions of hexagonal phase are compatible with a bilayer matrix.