Macroglobulin antibodies in the natural immune response to endotoxin in Escherichia coli associated enteritis in the weaned pig

Abstract

Serological studies of 10 pigs with E. coli (0141: K85a, c(B): H4) associated enteritis have been carried out. The level of somatic (O) antibody determined by the antiglobulin haemagglutination test in 7 pigs with enteritis exceeded the range found in normal pigs. Fractionation studies with Sephadex G200 and DEAE cellulose demonstrated that the antibody was associated with the high molecular weight immunoglobulin fraction of pig serum. Ultracentrifugal analysis of this fraction indicated an S 20 value of 17·8 (18S immunoglobulin). Two immunoglobulins were identifiable in this high molecular weight fraction, IgM and IgG. A specific rabbit antiserum for IgM was prepared and inhibition studies with the pig serum fraction indicated the antibody was associated with IgM. A small proportion of the antibody was associated with 7S IgG. This appeared to be incomplete because it was only detected by the antiglobulin haemagglutination test. Electrophoretic serum protein patterns of diseased pigs showed an almost consistently decreased albumin level, possibly due to loss into the lumen of the intestine.