Effect of immunoglobulins and IgG-fragments on the human erythrocyte aggregation, studied by a rheoscope combined with image analyzer

Using a rheoscope, combined with a TV image analyzer and a computer, the effects of immunoglobulins and IgG-fragments on the process of human erythrocyte aggregation were determined. The immunoglobulins accelerated the aggregation; the effect increased with their molecular weight, i.e., IgG ≃ γ-globulin < IgA < IgM. An empirical relationship, expressing the dependence on the immunoglobulin concentrations, was proposed. F(ab')₂-fragment accelerated the aggregation, more effectively than IgG, while Fab- and Fc-fragments did not. Therefore, two Fab-portions are presumably needed to form the aggregates, and the flexibility between two Fab-portions may be important. A case of multiple myeloma showed an increased aggregation, due to increased myeloma protein.