Tumour immunoprophylaxis exerted by the antimicrococcus immunity. I. Influence on the proliferation of murine leukaemic L1210 cells

Abstract

An immunization schedule that leads to the production of antimicrococcus antibodies of restricted electrophoretic heterogeneity in (female BALB/c × male DBA/2) F 1 mice (CDF 1 ) is described and commented on. Although mouse antimicrococcus sera agglutinate cultured L 1210 cells in vitro, micrococcus vaccinated mice never showed any anti-leukaemia immunoprotection. However, vaccinated mice, given booster doses of 1 mg heat-killed Micrococcus lysodeikticus on days 4, 8 and 12 after a tumour challenge of 10 4 cells, were considerably protected (P < 0.001) and showed a 92% increase in mean life span over untreated controls, with 57% of long-term survivors, whereas unvaccinated mice, given 1 mg micrococcus injections on days 4, 8 and 12, showed a 72% increase in mean life span (P < 0.001), but no long-term survivors were recorded. Our results underline the idea that, after establishment of tumour growth, the humoral antitumour immunity requires an adequate trigger of immunocompetent effector cells to be operationally effective.