Protection against MOPC-315 plasmacytoma by immunization with C-type particle preparations.

Mice were given injections of C-type particles extracted from the ascitic fluid of plasmacytoma-bearing mice. These particles, extracted from MOPC-315 tumor-bearing mice and injected into BALB/c mice, protected them against challenge with MOPC-315 tumor cells. The protection was dependent upon tumor cell dose; 66% survival was observed with a lethal dose of tumor cells. No protection was observed against challenge with another plasmacytoma (S13). Attempts to protect mice against S-13 plasmacytoma by immunizing them with C-type particles originating from S-13 tumor-bearing mice were unsuccessful.