Scanning electron microscopical characterization of La 3+- and Concanavalin A-induced aggregations of untreated and neuraminidase-treated human erythroeytes

Abstract

The aggregates of washed control and NANAse-treated human red blood cells (RBC) were characterized by scanning electron microscopy (SEM). Aggregation of RBC was performed under well-defined laminar shear conditions (78.6 S-1) in a horizontally arranged coaxial cylinder system. Generally, with increasing La3+ concentration in the PBS the aggregates became larger and the contact between the RBC "more intensive". This was evidenced by more cells per aggregate, an enlargement of contact areas, a change of cell shape in the contact region and signs of fusion phenomena. Especially at high La3+ concentrations on the cell surface of treated and untreated RBC some deposits were seen by SEM which are possibly La3+- phosphate precipitates. Neuraminidase treatment promoted the described La3+ effects. Concanavalin A-induced RBC agglutinates were different from the more spherical former ones and showed a network-like morphology. The conclusions drawn on the basis of light and scanning electron microscopical investigations are confirmed by quantitative values of an aggregation index estimated in parallel.