Lrr. Castellobranco et al., CHARACTERIZATION OF THE CIRCULATING T-CELL RESPONSE AFTER ORAL IMMUNIZATION OF HUMAN VOLUNTEERS WITH CHOLERA-TOXIN-B SUBUNIT, Vaccine, 12(1), 1994, pp. 65-72
The kinetics and phenotypic characterization of the in vitro cell prol
iferative response to the B subunit of cholera toxin were studied usin
g peripheral blood mononuclear cells taken from human volunteers at fr
equent time points after primary and booster oral immunizations. The c
ells induced to proliferate by oral immunization secreted IL-3, and li
popolysaccharide depletion and depletion of B cells did not affect pro
liferation. Flow cytometry demonstrated that activated cells were CD3-
and CD4-positive. These findings indicate primed T cells proliferatin
g specifically to the B subunit. The kinetics of the response suggeste
d trafficking in the peripheral circulation of primed T cells from the
gut, with a peak stimulation index of between 7 and 93 after first im
munization, and a precursor frequency of primed cells of between 1 in
25400 and 1 in 72390. There was close correlation between the serum an
titoxin IgA antibody levels and observed proliferation.