FcR+/- subsets of Ia+ pulmonary dendritic cells in the rat display differences in their abilities to provide accessory co-stimulation for naive (OX-22+) and sensitized (OX-22-) T cells.
A substantial body of evidence indicates that the primary sensitization of naive T cells to inhaled antigens occurs in the regional lymph nodes, whereas secondary responses may be generated directly within lung tissue. Ia+ pulmonary dendritic cells are widely distributed within the rat lung where they can participate in the induction of the immune response to inhaled antigens. Recently, two subsets of Ia+ pulmonary dendritic cells have been distinguished based on their expression of Fc receptors (FcR), but little is known concerning their abilities to support the responses of naive or sensitized T cells. In order to address this question, pulmonary FcR+/- dendritic cells have been purified from enzymatic digests of Lewis rat lungs, based on their differential binding to heat-aggregated immunoglobulin. The FcR+/- dendritic cell subsets differed with respect to their light microscopic appearance and in their expression of non-specific esterase. Only the FcR+ subset was able to phagocytize latex beads and showed intracellular phagolysosomes by electron microscopy. Both of the FcR+/- subsets rapidly formed clusters with naive (OX-22+) and sensitized (OX-22-) T cells. However, the clusters yielded by the FcR+ subset were substantially smaller, possibly reflecting their diminished surface membrane expression of the intercellular adhesion molecule-1. The FcR+/- subsets were capable of presenting soluble and particulate antigens to OX-22- T cells. FcR+ cells were less effective than FcR- cells in promoting the proliferative response of OX-22+ T cells to concanavalin A and in the primary mixed leukocyte reaction. We conclude that the FcR+/- pulmonary dendritic cells differ in their abilities to support the responses of naive and sensitized T lymphocytes. This observation may have significance for how primary and secondary pulmonary cell-mediated immune responses are generated.
Kradin
R L
RL
Department of Pathology, Massachusetts General Hospital, Boston 02114.
Xia
W
W
McCarthy
K
K
Schneeberger
E E
EE
D000818:Animals; D000938:Antigen-Presenting Cells / Q000502:physiology*; D002449:Cell Aggregation; D003208:Concanavalin A / Q000494:pharmacology; D003713:Dendritic Cells / Q000378:metabolism*; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D007114:Immunization; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D051381:Rats; D011917:Rats, Inbred Lew; D011961:Receptors, Fc / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000187:drug effects; D013601:T-Lymphocytes / Q000502:physiology*
D000949:Histocompatibility Antigens Class II; D011961:Receptors, Fc; D003208:Concanavalin A