Alterations of immune response of DBA/2 mice by procarbazine treatment

Bacterial lipopolysaccharide (LPS) and sheep red blood cells (SRBC) were used as antigens to investigate the in vivo dose- and time-dependent effects of procarbazine (PCZ) treatment on antibody responses of adult male DBA/2 mice. The mice were exposed to different doses of PCZ (100, 300, and 600 mg/kg) and then immunized with LPS or SRBC at days 0, 7, 14, and 21. Procarbazine treatment had essentially no effect on the number of LPS antibody-producing cells in spleens of mice in the entire range of PCZ dose and time, while the circulating antibody to LPS in serum diminished in mice treated with 600 mg/kg dose. In contrast, PCZ treatment altered the plaque-forming cell (PFC) response of the mice to T-cell dependent antigen SRBC. At 100 mg/kg dose, a slight stimulation of immune response was noticed. However, at higher doses (300 and 600 mg/kg), the number of antibody-producing cells to SRBC was decreased. This decrease was 87% at the highest dose compared to the untreated mice. Besides the antibody-producing cells in spleen, the antibody titer to SRBC in serum was also significantly diminished. This markedly reduced immune response, however, was released with the passage of time and was almost completely recovered by day 21 after the PCZ treatment of the mice. In addition, a very significant decrease in the number of cells per spleen was observed at 600 mg dose. It is suggested that PCZ exerts its immunosuppressive effects by essentially affecting T cells, both by decreasing the antibody synthesis as well as the number of cells.