Figure 2. Mitogenic activity of acute-phase serum samples 96/2 and 99/1 compared to recombinant superantigens (SAgs). Peripheral blood lymphocytes were stimulated for 4 d with various dilutions of recombinant SAg or acute-phase serum sample 99/1. No dilution was carried out for 96/2 because of limited amount of serum. Five percent of each of the patient serum samples showed a proliferative response equal to 1–10 pg/mL of recombinant streptococcal pyrogenic exotoxin J or recombinant streptococcal mitogenic exotoxin 1. Serum 99/1 still showed significant mitogenic activity at 0.05%. SME, antistreptococcal mitogenic exotoxin; SPE, antistreptococcal pyrogenic exotoxin.