School
School of Public Health
Document Type
Dissertation
Department (new version)
Public Health
Date of Award
1997
Degree Name by School
Doctor of Public Health (DrPH) School of Public Health
Abstract
To investigate the importance of high dose vitamin A in the immune response and regulatory function of T helper (Th) cells to influenza A viral pneumonia, BALB/c mice were fed a high dose vitamin A diet (250,000 IU/kg diet) or a control diet (4,000 IU/kg diet) and then were intranasally inoculated with influenza A virus under light anesthesia at 7 weeks of age. The effect of these diets on vitamin A status (serum and liver retinol concentrations), severity of disease (survival and weight loss), virus replication, the antibody response to infection (serum IgG and salivary IgA), and on cytokine production by lymphocytes isolated from the spleen and mediastinal lymph nodes were examined. Serum retinol levels at the time of infection were higher in the 250k vitamin A intake group (30.0 $\pm$ 5.42 ng/L) than in the 4k intake group (22.1 $\pm$ 5.96 ng/L; $p < 0.05).$ The same was also true of liver vitamin A stores (5.75 $\pm$ 0.41 mg/g liver in 250k group; 0.25 $\pm$ 0.07 mg/g liver in 4k group; $p < 0.0001$). Survival and changes in body weight did not differ between the groups. No difference was found in the virus titers in the lungs of infected mice between diet groups after infection. The influenza-specific IgA in saliva was significantly higher in the high-dose vitamin A supplement group ($p <0.05).$ The total IgA in saliva and influenza-specific IgG in serum were not significantly different. In vitro, the high dose vitamin A stimulated a strong Th2 cell response, with an increased level or interleukin-10 (IL10) and a suppression of Th1 cell response, with decreased level of interferon-$\gamma$ (IFN-$\gamma$). These differences were statistically significant ($p <0.05$). These results identify high-dose vitamin A activities that balance Th1 and Th2 function by down-regulating Th1 cell IFN-$\gamma$ secretion and promoting Th2 cell function in increased IL-10 and influenza-specific IgA production. However, the high-dose vitamin A did not improve mice mortality from influenza viral pneumonia when the treated mice were compared with the control group. In addition, such supplements alter the Th1/Th2 balance in a manner that does not favor an anti-viral immune response. Therefore, the consequences of over pushing the response in a Th2 direction in BALB/c mice are unclear.
ProQuest Publication Number
ProQuest ID
9804941
ISBN
978-0-591-56517-1
Recommended Citation
Cui, Dongming, "High-dose vitamin A supplementation and immune response to influenza A viral pneumonia in BALB/c mice" (1997). All ETDs from UAB. 7195.
https://digitalcommons.library.uab.edu/etd-collection/7195
Comments
DrPH