According to the research’s participants, study population focus on children’s age around 2-12 years old in the United states , who had signs and symptoms have acute pharyngitis , group A streptococci from preliminary visit throat , and convalescent sera were acquired 4 weeks father. Moreover, the recombinant SCPA peptide was used as antigen including coated overnight on microliters plates as well. Acute and convalescent sera from the identical patient were always run contiguous to each other on the same micro plate under identical conditions. After incubation with secondary antibody (alkaline phosphatase-conjugated goat anti-human IgG) the substrate, p-nitro phenyl phosphate was accrue including the enzyme reaction was stopped. In anti-SCPA concentrations were seen in mutually acute and convalescent sera of 72 children included in the study as well. In generally, the mean convalescentanti-SCPA was twice the concentration of mean acute anti-SCPA. The paired acute and convalescent sera were examined, included over two-thirds of the children studied demonstrated a significant rise, i.e., > 15 per cent rise in recovering anti-SCPA concentration. It was seen mean rise in recovering antiSCPA ensued all of the represented age groups between 2 and 12 year, when the immune response to SCPA was examined according to age. The child age of 5 years that had a higher amount of response. Therefore, it was found that a mean rise in anti-SCPA occurred irrespective of the M type, proposing that all M types produced SCPA, when the immune response to SCPA was plotted allowing to M type of the contaminating strain.