Dynamics of Lymphocyte Subpopulations in Immune Organs of Chickens Infected with Salmonella enteritidis
To determine the effect of different doses of Salmonella enteritidis on immunocompetent cells,
the thymus, bursa of Fabricius, and peripheral blood were examined. One-day-old chickens were
orally infected with 2 × 102CFU/ml (low dose) and 2 × 108 CFU/ml(high dose) of S. enteritidis PT4.
Subsets of T lymphocytes (CD3, CD4, and CD8), and BU1b cells using an indirect
immunofluorescent method and flow cytometry were analysed on days 7, 10, 14, 21, and 27 postinoculation (dpi). The actual number of lymphocytes in the peripheral blood showed a significant
increase in the low dose group (P < 0.05) on day 21 pi, and in the high dose group on day 27 pi
(P< 0.001) compared to controls. The increase of CD3+, CD4+, and CD8+ T cells was observed in both
infected groups compared to the controls from day 14 pi, significant on day 21 pi (P < 0.05) in the
high dose group. The subpopulation of CD8+ was higher also on day 27 pi (P < 0.01) compared with
the values of the control group. The subpopulation of BU1b+ B cells in both infected groups showed
higher values, but without significant differences from controls. The thymus T lymphocytes showed
a significant decline in CD3+ T cells on day 7 pi, whereas CD4+ T cells were significantly (P < 0.05)
increased on day 7 pi in both infected groups. The bursal lymphocytes showed a decrease in BU1b+
B cells in both infected groups compared with the control group, significant in the high dose group
on day 21 pi (P < 0.05). These results indicate that S. enteritidis infection induced the changes in
immunocompetent cells, included cellular and humoral immune response. Salmonella infection
accelerated the maturation and differentiation of thymus T cells in the first phase of infection, what
was secondarily reflected by increased number of studied T lymphocyte subpopulations in the
peripheral blood from day 14 to 27 after infection. Similarly, it appears that the activation of B cells
in bursa of Fabricius caused the decrease number of bursal B lymphocytes and increased number of
these cells in the peripheral blood from day 14 to 27 pi in both infected groups.
A. A. Asheg(3-2003)
publisher's website