Stability and immunological reactivity of recombinant membrane CD4 electroinserted into the plasma membrane of erythrocytes

Concentration-dependent electroinsertion of recombinant human membrane CD4 in human erythrocytes shows a saturation at an average of about 3,500 inserted CD4 epitopes per cell, detectable by flow cytometry. The erythrocyte recovery drops to 10% at this high level of electroinsertion. Experimentally an optimum for cell recovery and insertion rate was found at about 2,500 CD4 epitopes per red blood cell. In vitro stability assay by flow cytometry indicated a temperature- and medium-dependent decrease in the number of CD4 epitopes inserted per cell. This decrease is biphasic, with an exponential part during the first 24 h after electroinsertion followed by a much slower linear decay.