The Reactive Nature Of Acute Rheumatic Fever: Evidence From Streptococcal Cell Wall Antigen Detection By Immunotechnology|
Abo-Zenah, H; Al-Hendy A; Ismail H & El-Sayed I
The life-threatening group A streptococcal (strep) infection and its sequelae, including acute rheumatic fever (ARF), re-emerged as a serious health problem. The fleeting arthritis of ARF is considered a form of reactive arthritis. However, no one has confirmed this by investigating its synovial fluid cells for a possible presence of strep cell wall antigens using western blot in humans. This is the aim of the current study.
Synovial fluid- (SF) and peripheral blood-mononuclear cells (PB-MNCs) from 40 patients with ARF and 10 patients with rheumatoid arthritis (RA), who served as a control group, were examined for strep antigens by immunofluorescence (IF) and western blot (WB) techniques using rabbit polyclonal antiserum and mouse monoclonal antibodies.
Extensive bacterial cultures of SF, blood and throat were negative. By IF, a significant proportion (37.5%) of ARF samples (Chi-square=3.72, p=0.048) showed positive staining in SF- as well as PB-MNCs with both rabbit polyclonal antiserum and mouse monoclonal antibodies. Further, IF was significantly higher in ARF- than RA-patients (Mann-Whitney p=0.022) in whom we failed to observe any staining.
By immunoblotting, 21 samples from ARF patients (52.2%) were positive with mouse monoclonal antibodies specific for strep peptideglycan-polysaccharide (PG-PS) complex in SF-Cs (a band with a molecular weight of 28 kD) and PB-MNCs (29kD) and its proportion was significant (p=0.0008). With rabbit polyclonal antiserum, significant blots (p=0.027) were noted in 27/40 ARF patients (67.5%) indicating strep PG-PS (24-29kD broad band) in SF-Cs and PB-MNCs. Blots by both mono- and poly-clonal antibodies were significantly higher (p=0.003&=0.001, respectively) than control samples that were non-reactive using both types of antibodies.
The reactive nature of acute rheumatic fever is suggested by the frequent detection of streptococcal cell wall antigen from affected joints using both, immunofluorescence and western blotting.
Streptococcal antigen, Rheumatic fever, Rheumatoid arthritis.