21
Antonio), to take them to the bench and perform a T-cell
activation experiment in front of their eyes. He will take a
culture of lymphocytes and place the petri dish over the lens of
an inverted Zeiss, and ask you to focus at magnifi cation 40. The
cells are swimming graciously, dancing in Brownian motions;
they do not touch. Now Antonio adds normal dendritic cells
that have been collected from the same donor. The lymphocytes
show some interest in the newcomers; when passing near
each other, two cells make contact, their membranes seem to
move and unfold as they seem to circle each other. They have
explored each other thoroughly, but they have not found reason
for further interest, and they leave in different directions. Next,
Antonio adds ...