Al. Smith et Bf. De St Groth, Antigen-pulsed CD8 alpha(+) dendritic cells generate an immune response after subcutaneous injection without homing to the draining lymph node, J EXP MED, 189(3), 1999, pp. 593-598
Two subsets of murine splenic dendritic cells, derived from distinct precur
sors, can be distinguished by surface expression of CD8 alpha homodimers. T
he functions of the two subsets remain controversial, although it has been
suggested that the lymphoid-derived (CD8 alpha(+)) subset induces tolerance
, whereas the myeloid-derived (CD8 alpha(-)) subset has been shown to prime
naive T cells and to generate memory responses. To study their capacity to
prime or tolerize naive CD4(+) T cells in vivo, purified CD8 alpha(+) or C
D8 alpha(-) dendritic cells were injected subcutaneously into normal mice.
In contrast to CD8 alpha(-) dendl-itic cells, the CD8 alpha(+) fraction fai
led to traffic to the draining lymph node and did not generate responses to
intravenous peptide However, after in vitro pulsing with peptide, strong i
n vivo T cell responses to purified CD8 alpha(+) dendritic cells could be d
etected. Such responses may have been initiated via transfer of peptide-maj
or histocompatibility complex complexes to migratory host CD8 alpha(-) dend
ritic cells after injection. These data suggest that correlation of T helpe
r cell type 1 (Th1) and Th2 priming with injection of CD8 alpha(+) and CD8
alpha(-) dendritic cells, respectively, may not result from direct T cell a
ctivation by lymphoid versus myeloid dendritic cells, but rather from indir
ect modification of the response to immunogenic CD8 alpha(-) dendritic cell
s by CD8 alpha(+) dendritic cells.