The use of frozen erythrocytes in macrophage studies. 1. Attachment to the foreign surface receptor of the macrophages.

The attachment of red cells to mouse peritoneal macrophages in vitro was tested with erythrocytes (from sheep and man) which had been subjected to different cryoprotective agents and freezing procedures. The experiments showed that with dimethylsulfoxide (DMSO) as the cryoprotective agent no difference in macrophage attachment was seen whether the erythrocytes were frozen or not. With the other cryoprotectants tested, macrophages were more efficient in attaching frozen than unfrozen erythrocytes. This was the case with erythrocytes from both sheep and man. Similar results were obtained with fresh (one week) and old (two weeks) erythrocytes.