Effect of prolonged administration of low doses of dietary retinoids on cell-mediated immunity and the growth of transplantable tumors in mice.
A study was conducted on the activity exerted by prolonged dietary supplementation with progressive amounts of retinoids on cell-mediated immune responses and the growth of transplantable tumors in mice. A few groups of BALB/c mice received 0 (group C), 50 (group A 50), 200 (group A 200), 500 (group A 500), and 1,000 (group A 1000) IU retinol palmitate/mouse/day in drinking water for 150 days. At progressive intervals mice from each group were tested for proliferative responses to concanavalin A (Con A), Escherichia coli lipopolysaccharide, interleukin-2, and interferon-gamma release to Con A. Ten mice from each group were also challenged with the 90-100% tumor-inducing dose of 3 distinct transplantable tumors. At the end of the experiment the principal organs were histologically examined, and the accumulation of vitamin A was evaluated. In groups A 200, A 500, and A 1000, an increase in the proliferative responses and production of lymphokines as compared to those in group C occurred after 60-90 days, but vanished after 150 days. The takes of the 3 tumors were impaired when the challenges were performed on days 75 and 150. This enhancement of distinct functions of cellular reactivity and resistance to transplantable tumors showed a linear relationship with the amount of supplemental retinol palmitate for the first 60-90 days. After 150 days, however, these enhancement effects vanished or tended to decrease.
Forni
G
G
Cerruti Sola
S
S
Giovarelli
M
M
Santoni
A
A
Martinetto
P
P
Vietti
D
D
D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology; D004032:Diet; D004224:Diterpenes; D004305:Dose-Response Relationship, Drug; D005260:Female; D005354:Fibrosarcoma / Q000473:pathology; D007111:Immunity, Cellular / Q000187:drug effects*; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008325:Mammary Neoplasms, Experimental / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000276:immunology / Q000473:pathology*; D012176:Retinoids / Q000008:administration & dosage* / Q000494:pharmacology; D000084562:Retinyl Esters; D014801:Vitamin A / Q000031:analogs & derivatives / Q000494:pharmacology
D004224:Diterpenes; D007376:Interleukin-2; D008070:Lipopolysaccharides; D012176:Retinoids; D000084562:Retinyl Esters; D003208:Concanavalin A; D014801:Vitamin A; C014794:retinol palmitate; D007371:Interferon-gamma