Figure 6.

Agonist like effect of affinity-purified anti-R13 and anti-H26R antibodies from cChHD and SLE sera. The specificity of the effect was studied by inhibition with the β₁-specific antagonist bisoprolol (bisop) and the peptides R13, P0β, and H26R. Cells were subsequently stimulated with the β-adrenergic agonist isoproterenol (isop). Bars represent mean ± SD of the increase in beats/min. ∗, Significant differences (P < 0.01) were observed between results with purified antibodies alone and after treatment with the inhibitors. Ab stands for affinity purified antibodies against peptides R13 or H26R.