Related Experiment Videos
Protein A-like activity and streptococcal cross-reactions
Clinical and Experimental Immunology
|October 1, 1981
Summary
Group A streptococci lack protein A-like activity, challenging previous findings of cross-reactions with mammalian tissues. This study clarifies that bacterial cell walls did not cause the observed non-specific antibody absorption in earlier research.
Area of Science:
- Immunology
- Microbiology
- Biochemistry
Background:
- Previous studies suggested antigenic cross-reactivity between group A streptococci and mammalian tissues, potentially due to protein A-like activity.
- This protein A-like activity was hypothesized to cause non-specific binding of antibodies, confounding experimental results.
Purpose of the Study:
- To re-evaluate the presence of protein A-like activity in group A streptococci strains previously implicated in cross-reactivity studies.
- To determine if this activity was responsible for the non-specific absorption of human IgG observed in earlier research.
Main Methods:
- Utilized the mixed reverse passive antiglobulin reaction (MRPAH) assay.
- Tested strains of group A streptococci and a control strain of Staphylococcus aureus for the absorption of purified human IgG Fc portion.
Main Results:
- Group A streptococci strains showed only trace levels of protein A-like activity.
- The control Staphylococcus aureus strain exhibited strong positive results for protein A-like activity.
- The previously observed non-specific absorption was not attributable to protein A-like material in the streptococcal strains.
Conclusions:
- The protein A-like activity in group A streptococci is minimal and unlikely to be the cause of previously reported antigenic cross-reactions.
- Earlier findings suggesting cross-reactivity due to this activity require re-evaluation.
- The study clarifies the role of bacterial components in non-specific antibody binding in immunological assays.