Biological variation of anti-αGal-antibodies studied by a novel Time-Resolved ImmunoFluorometric Assay

As much as one percent of antibodies in human plasma are reported to be specific for the non-human disaccharide structure αGal. Various microbes express αGal. However, the implications of anti-αGal antibodies for the anti-microbial defenses are poorly established. With the perspective of studying the biological importance of the antibodies, we have established a sensitive Time-Resolved ImmunoFluorometric Assay (TRIFMA) for quantification of such antibodies. Two versions were developed, one for IgM antibodies and one for IgG antibodies. Samples were collected from plasma donations of healthy adults (n=120) of known gender (60+60), AB0-type (0: 15+15, A: 15+15, B: 15+15, and AB: 15+15) and age (19-64 yrs). We subsequently examined the potential association between antibody concentration and AB0-type, gender, age, and titers of antibodies to blood type antigens. We found that IgG and IgM anti-αGal concentrations are, 1) stable over time within the individual, 2) vary more than 400-fold between individuals, 3) negatively correlated with age for IgM but not for IgG antibodies, 4) IgM antibodies are 2-fold higher in females whereas no gender difference was observed for the IgG antibodies, 5) inter-mutual correlated, 6) lowest in individuals expressing B-antigen, and 7) AB0-type A individuals may constitute an intermediate group. Our established method and findings pave the way for further studies of the involvement of anti-αGal antibodies in immunity and may be a method to examine the potential of an individual to mount an anti-carbohydrate response.