192 sera containing cold agglutinins of apparent anti-I specificity were reinvestigated for concomitant
cold agglutinins (CA) against sialic acid-dependent antigens. 35 cases of additional anti-Fl and 3 cases of additional
anti-Gd were detected. 53% of cases with coexisting anti-I and anti-Fl/Gd CA had a clinical diagnosis of pneumonia,
in 39% IgM antibodies against Mycoplasma pneumoniae could be demonstrated. Since FI and Gd antigens are
identical with the structures identified as receptors for M. pneumoniae, the findings support the hypothesis that
postinfectious CA are directed against the receptor of the infectious agent.
The antigens Fl and Vo, recognized by cold agglutinins, are protease-resistant differentiation antigens like I and i antigens. In contrast to Ii, Fl and Vo are sialidase-susceptible antigens like the protease-resistant Gd antigens. Because I/i antigens are branched/linear type-2 (poly-N-acetyllactosamine or neolacto series) chains which are cleaved from red cells by endo-β-galactosidase, the effect of the enzyme on Fl, Vo and Gd antigens was studied. FI and Gd antigens, previously shown to be sialylated branched (Fl), and linear and branched (Gd) type-2 sequences, were not inactivated on red cells by the enzyme, whereas Vo antigenicity was completely abolished. The data suggest that Vo antigen is expressed on sialylated linear poly-N-acetyllactosamine sequences.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.