Further Observations on the Preparation of Antiglobulin Reagents Reacting with C3d and C4d on Red Cells 1

. 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.