Enzyme-linked immunosorbent assay for anti-streptococcal protoplast membrane antibodies.

An enzyme-linked immunosorbent assay is described for the quantitative determination of circulating antibodies to streptococcal protoplast membranes (SPM) in human sera. The assay was used to study the prevalence of antibodies to SPM of M types 6 and 12 Streptococcus pyogenes in sera from 55 patients with recent streptococcal infection, and 30 normal individuals without clinical evidence of streptococcal infection. No correlation was found between levels of anti-SPM antibodies and ASO titres. However, in serial serum samples from one patient with uncomplicated streptococcal sore throat, it was possible to demonstrate that the increase in the level of anti-SPM antibody paralleled the rise in ASO titre. The anti-SPM antibody level and the ASO titre in this patient persisted throughout a six-month period of follow-up.