Further observations on the preparation of antiglobulin reagents reacting with c3d and c4d on red cells.

A simplified method was developed for preparing rabbit red cells coated only with human C3d by the alternative pathway; these cells were injected into the donor rabbit to prepare an anti-C3d serum. Monkey red cells were sucessfully coated with human C4d, using a low-ionic-strength method, and these cells were injected into the donor monkey to prepare anti-human C4d. The reactions of these reagents were compared with those of antisera raised to complement-coated red cells by previously described methods and with those of antisera obtained by immunizing rabbits with purified soluble human C3d.