Infect Immun, August 1998, p. 3562-3568, Vol. 66, No. 8
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Department of Medical Microbiology and Immunology, College of Medicine, Texas A&M University Health Science Center, College Station, Texas 77843
Received 17 December 1997/Returned for modification 18 February 1998/Accepted 13 May 1998
Protein malnutrition leads to multiple detrimental alterations of
host immune responses to mycobacterial infection. In this study, we
demonstrated that splenocytes from low-protein (LP) guinea pigs
vaccinated 6 weeks previously with attenuated Mycobacterium tuberculosis H37Ra failed to control the accumulation of virulent M. tuberculosis H37Rv in cocultured autologous peritoneal
macrophages, despite the fact that they were able to control the
accumulation of virulent tubercle bacilli in cocultured syngeneic
peritoneal macrophages from normally nourished guinea pigs as
successfully as did those from high-protein (HP) counterparts.
Vaccine-induced growth control of virulent M. tuberculosis
H37Rv in these cocultures appeared to be mediated by CD4 lymphocytes
but not CD8 cells. Tuberculin (purified protein derivative
[PPD])-induced lymphoproliferation was markedly impaired in
vaccinated LP guinea pigs, and the depletion of CD4 lymphocytes
significantly decreased lymphocyte proliferation whereas CD8 cell
depletion did not. Protein malnutrition also impaired the abilities of
cells from vaccinated LP guinea pigs to produce cytokines, including
interferon, tumor necrosis factor alpha (TNF-
) and transforming
growth factor beta (TGF-
), in response to PPD, despite the
demonstration of higher serum levels of TNF-
and TGF-
after an
intravenous injection of PPD into LP guinea pigs. In contrast,
peritoneal macrophages from protein-malnourished guinea pigs produced a
higher level of TGF-
4 days after infection in vitro with M. tuberculosis H37Rv than did those from protein adequate controls.
These results suggest that dietary protein malnutrition impairs
vaccine-induced resistance to M. tuberculosis, in part, by
altering the cytokine profile to favor macrophage deactivation.
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