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I I I I I I I I i I I I I I I I i I AUTHOR; KEAST, D. AND D. AYRE DATE: 1980 TITLE: EFFECTS OF CHRONIC TOBACCO SMOKE EXPOSURE ON IMMUNE RESPONSES IN AGED MICE CITATION: ARCHIVES OF ENVIRONMENTAL HEALTH. 36:201-207, 1981. ~: Balb/c mice were exposed to fresh smoke equivalent to 30 high-tar filtered cigarettes/day. Mice exposed for 7-8 minutes on 5 consecutive days/wks up to 84 wks. Fresh smoke mixed with air to achieve a 1:7 ratio. 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 plauqe-forming cells, spleen cell and lymph node phytohemagglutinin (PHA) responses, and systemic clearance of normal and opsonised antigen were investigated. FINDINGS/RESULTS: Aged TS-exposed mice displayed lowered antibody titers against SRBC after 56 wk exposure, but produced titers equal to or greater than control levels after 64,72 and 80 wk exposure. Exposure to tobacco smoke does not appear to affect pfc numbers 8 days after IP SRBC inoculation. Antibody responses to the "B-cell antigen," PVP remain unaffected by up to 80 wk TS exposure. Both splenic and RLN PHA responses were significantly depressed by up to 72 wk TS exposure. However, after 80 weeks, control and TS exposed mice showed similar levels of response to PHA. Clearance of SRBC from circulation after a primary IV inoculation was delayed by 56 wk TS exposure, but was unaffected by more prolonged exposure. The clearance of opsonised SRBC or a secondary inoculum from circulation was not significantly affected by TS exposure. This group had shown that growth of implanted tumors was enhanced in mice by 26 wk TS exposure, but initially the TS-exposed mice were better able to reject implanted tumors than the controls. The results from this study also suggest that the spread of metastases occurs earlier in aged TS-exposed mice, 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.