The ability of antisera to lipid A, induced in rabbits by immunization with lipid A complexed to various carriers, to protect mice against gram-negative infection and to inhibit the fluid loss caused by an enteropathogenic strain of Escherichia coli in the piglet ligated gut was investigated. No significant protection was obtained in either case, although passive hemolysis and quantitative precipitation tests showed the presence of antilipid A antibodies in the sera. Fluorescent antibody studies suggest that the lipid A is in a cryptic position on the surface of smooth strains of gram-negative bacteria.

Complexes of dextran 20 000 with haemoglobins of sheep, rabbit, dog, bovine and human origin were prepared through alkylation of haemoglobin by N-bromoacetylaminoethylamino-dextran. The yields were uniformly high. Complex-formation in each case was accompanied by the disappearance of reactive thiol groups on the haemoglobin, and by an increase in the affinity of the haemoglobin for oxygen. The immunological properties of dog, rabbit and sheep dextran-haemoglobin were investigated in both homologous and heterologous species. The complexes were found to be non-immunogenic in the homologous species. In heterologous species the anti-haemoglobin response induced by each complex was generally of a similar level to that induced by the haemoglobin alone.

Davis, P., Cunnington, P., and Hughes, G. R. V. (1975). Annals ofthe Rheumatic Diseases, 34,239-243. Double-stranded RNA antibodies in systemic lupus erythematosus. Antibodies to viral double-stranded RNA (ds RNA) have been found in 40% ofpatients with systemic lupus erythematosus (SLE) and 14-5 % of patients with rheumatoid arthritis. These antibodies were diagnostically more specific for SLE than those directed against artificial polynucleotides, poly I: C and poly A: U. Although not disease specific, high titres of antibody to ds viral RNA were found almost exclusively in SLE. Serial studies failed to show that RNA antibody levels correlated with disease activity.Although of considerable interest in experimental studies on the pathogenesis of SLE, ds viral RNA antibodies are of little clinical significance in the management of SLE.Systemic lupus erythematosus (SLE) is characterized by a wide variety of circulating antibodies. In particular, antibodies against double-stranded DNA (ds DNA) have been shown to have clinical significance in their diagnostic specificity and sensitivity in SLE (Hughes, 1971;Hughes, Cohen, and Christian, 1971). Ofinterest has been the demonstration in SLE of antibodies directed against double-stranded RNA (ds RNA) (Schur and Monroe, 1969;. This finding, together with the fact that most human RNA is single stranded, has led to the suggestion that these antibodies may be directed against viral antigens (Schur, Stollar, Steinberg, and Talal, 1971).A variety ofmethods has been used in the detection of RNA antibodies, including the sensitive Farr technique (Wold, Young, Tan, and Farr, 1968) and the filter radioimmunoassay technique (Attias, Sylvester, and Talal, 1973). The antigen most widely used in these techniques has been the synthetic polynucleotide poly inosinic:poly cytidylic acid (poly I: C), which has structural and chemical similarities to ds RNA. Using this technique, Schur and his colleagues (1971) detected antibodies against poly I: C in 51 % of SLE sera, but these were not specific, also being found in 9% of patients with rheumatoid arthritis (RA) and in 6 % of normals. In the present study we have substituted the synthetic polynucleotide poly I:C for a highly purified preparation of doublestranded viral RNA obtained from Penicillium cultures, and assessed the frequency and specificity of

The immunological properties of a naturally-occurring double-stranded ribonucleic acid (ds-RNA), obtained from a mycophage of Penicillium chrysogenum, have been studied in relation to molecular size. Materials of reduced size, as reflected by molecular weight measurements, produced by ultrasonication of native ds-RNA, exhibited progressively lowered ability to induce an anti-ds-RNA response in mice. Adjuvant and immunosuppressive activities were of similar magnitude in both high and low molecular weight fractions. Evidence was also obtained of increased toxicity in materials of reduced size.

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