Figure 3. MAR IgG reduces the amplitude of the b-wave originating from the rod bipolar cells.

A) Representative scotopic ERGs from one of 13 recorded mice. Light flashes were delivered at time 0; numbers to the right indicate scotopic flash intensity (log cd-s/m²). Traces from the IgG-injected eye are shown in red and from the sham-injected control eye in black. B) Solid lines show the fits of the Naka-Rushton function (eqn 1 in main text) to the plot of scotopic a-wave (top) and b-wave (bottom) peak amplitudes versus flash intensity measured from the above mouse A (red: MAR IgG-injected eye; black: control eye). The bottom plot is fitted with the ON-bipolar cell responses to dim light (from 10⁻⁵ to 10⁻¹ cd-s/m²). The a-waves of the two traces superimpose, but the b-waves of the MAR IgG-injected eye are of smaller amplitude. C) The suppression of the ERG correlates with uptake of the MAR IgG into ON-bipolar cells. After ERG recordings, the retinas were fixed, cryosectioned and reacted with anti-human IgG-Alexa594 (red) to visualize cells that accumulated MAR IgG. The sections were double labeled with PKC (green) to identify rod bipolar cells. The scale bar represents 20 µm.