Expression levels of human transferrin receptors in Neisseria species

Abstract

All pathogenic Neisseria strains synthesize transferrin receptors. To determine if transferrin receptor expression is quantitatively different in Neisseria meningitidis strains from two separate origins (carrier and invasive) and in commensal Neisseria, we applied an enzyme-linked receptor assay (ELRA) and a radiolabelled receptor assay (RLRA) to evaluate the receptor expression levels after iron-limited growth. There were significant differences in receptor expression in commensal Neisseria and Neisseria meningitidis as determined by both methods and between the two origins (invasive and carrier) when the ELRA method was used, but in the latter case, the biological significance is questionable and the amount of transferrin receptor expressed may not be a useful indicator of the potential pathogenicity of strains. The RLRA method was more suitable for measuring transferrin receptor expression since it provided a lower background in strains lacking transferrin receptor and, consequently, made interpretation of the results easier.