Fig 1.

Dose–response curve. Proliferative response of CD4⁺ and CD8⁺ cells upon in vitro stimulation with Streptococcal pyrogenic erythrogenic toxin A (SPE-A). CD4⁺ or CD8⁺ T cells (2 × 10⁴) and 10⁵ adherent, mitomycin C-treated autologous population from healthy donors, were co-cultured with varying amounts of SPE-A (•, CD4; ▪, CD8), anti-CD3 (20 ng/ml) alone (ct/min 86 462 ± 5710), anti-CD3 (20 ng/ml) with anti-SPE-A (80 926 ± 6515), anti SPE-A (6 μg/ml) raised in rabbit (○), normal rabbit serum (1:500 dilution). Normal rabbit serum was unable to cause inhibition of SPE-A (data not shown). The cultures were pulsed with ³H-thymidine after 48 h, for 16 h and data are presented as mean ct/min ± s.d., where experiments were conducted in triplicates.