Effects of chronic tobacco smoke exposure on immune responses in aged mice.

Balb/c mice were exposed to fresh smoke, equivalent to 30 high-tar filtered cigarettes/day, for 83 wk or less. After groups of mice were subjected to 56, 64, 72, and 80 wk of tobacco smoke (TS) exposure, serum antibody responses to both T-dependent and T-independent antigens, numbers of plaque-forming cells, spleen cell and lymph node PHA responses, and systemic clearance of normal and opsonised antigen were investigated. Aged TS-exposed mice showed some deterioration of immune responsiveness with age, but results varied; in extreme old age the immunological responsiveness of TS-exposed mice was similar to that of age-matched controls. In addition, groups of mice inoculated with fibrosarcoma cells after 78 wk TS-exposure did not show significantly greater susceptibility to the early development of pulmonary metastases.