Inhibition OF IgG-,F(ab′) 2 -and myeloma protein-induced erythrocyte aggregation,by small IgG-fragments

Abstract

The velocity of non-immune erythrocyte aggregation was determined by means of an automated rheoscope, consisted of an inverted microscope, a cone-plate viscometer, a TV image analyzer and a computer, in autologous plasma at a shear rate of 7.5/sec. As increasing the concentration of IgG and F(ab′)₂ added to diluted plasma, the velocity of aggregation increased, resembling the accelerated aggregation in 5 cases of multiple myeloma. Fab- and Fc-fragments scarcely affected the velocity; on contrary, they inhibited the aggregation induced by IgG or F(ab′)₂ as well as in multiple myeloma. As a plausible explanation of such inhibition, a competitive mechanism is suggested.