Apoptosis was especially reduced in CD4+CD25hi cells after restimulation with the nematode somatic antigen or studied fractions. In comparison with DEX, markedly fewer cells underwent apoptosis when exposed to rTNF-α (Figure 6). The subpopulation of CD3+CD4+ and CD+CD25hi lymphocytes both from naïve and infected

mice responded very weakly: the reduction in the percentage of apoptotic CD3+CD4+ cells of naïve mice was observed when AgS or fractions F9, F13 were added. After the exposition of CD4+CD25hi cells to AgS, fractions F9 or F13 the percentage of apoptotic cell increased, whereas F17 reduced apoptosis. Only CD3+CD8+ cells of infected mice survived better upon H. polygyrus antigen stimulation, and apoptosis was inhibited by AgS, F9 and F13. Fraction F9 significantly reduced apoptosis of CD8+ cells; to 8% after restimulation compared with the control sample. Fraction F17 induced screening assay an opposite effect to other fractions in all examined T-cell populations stimulated to apoptosis by rTNF-α; CD4+CD25hi and CD3+CD4+ cells were supported to survive

and only 10% of these cells were apoptotic. The same fraction restored apoptosis of CD3+CD8+ cells to the control level. The difference in activity of antigenic fractions were recognized mainly between F9 and F17 and examined cell populations responded distinctly to H. polygyrus somatic antigen fractions; the most sensitive cell population was CD4+CD25hi after exposure to DEX and CD3+CD8+ T cells after exposure to rTNF-α. The exposition of cells in vitro to H. polygyrus antigen SB431542 mouse resulted in changes in the percentage of Bcl-2-positive T cells in all examined subpopulations: CD3+CD4+, CD4+CD25hi and CD3+CD8+ (Figure 7). Infection and restimulation of CD3+CD4+ lymphocytes with the nematode antigen and all examined fractions increased the percentage of Bcl-2-positive cells and reached 65% in uninfected mice and 80% in infected mice. After

stimulation with AgS, F9 and F13, the percentage of CD4+CD25hi Bcl-2-positive cells in naïve mice decreased, but in infected mice achieved the control level, however, was still higher than in cells primary exposed to antigens in vitro. Infection with H. polygyrus increased the percentage of Bcl-2-positive CD4+ cells and restimulation of CD4+CD25hi with parasitic Verteporfin ic50 antigens restored the percentage to the control level for that cell population. In contrast, infection with H. polygyrus reduced the percentage of CD3+CD8+ Bcl-2-positive cells from above 80% in naïve mice to <20% in infected mice. The effect was enhanced by the nematode antigen and all antigenic fractions. FLIP appeared in cells isolated from infected mice (Figure 8). Heligmosomoides polygyrus antigen and its fractions with antiapoptotic activity increased FLIP expression both in cells of naïve, control mice and mice infected with the nematode.