Immunohistowax processing, a new fixation and embedding method for light microscopy, which preserves antigen immunoreactivity and morphological structures: visualisation of dendritic cells in peripheral organs.
OBJECTIVE
To describe a new fixation and embedding method for tissue samples, immunohistowax processing, which preserves both morphology and antigen immunoreactivity, and to use this technique to investigate the role of dendritic cells in the immune response in peripheral tissues.


METHODS
This technique was used to stain a population of specialised antigen presenting cells (dendritic cells) that have the unique capacity to sensitise naive T cells, and therefore to induce primary immune responses. The numbers of dendritic cells in peripheral organs of mice either untreated or injected with live Escherichia coli were compared.


RESULTS
Numbers of dendritic cells were greatly decreased in heart, kidney, and intestine after the inoculation of bacteria. The numbers of dendritic cells in the lung did not seem to be affected by the injection of E coli. However, staining of lung sections revealed that some monocyte like cells acquired morphological and phenotypic features of dendritic cells, and migrated into blood vessles.


CONCLUSIONS
These observations suggest that the injection of bacteria induces the activation of dendritic cells in peripheral organs, where they play the role of sentinels, and/or their movement into lymphoid organs, where T cell priming is likely to occur.
Pajak
B
B
Département de Biologie Moléculaire, Université Libre de Bruxelles, Belgium. bpajak@dbm.ulb.ac.be
De Smedt
T
T
Moulin
V
V
De Trez
C
C
Maldonado-López
R
R
Vansanten
G
G
Briend
E
E
Urbain
J
J
Leo
O
O
Moser
M
M
D000818:Animals; D003713:Dendritic Cells / Q000166:cytology / Q000502:physiology*; D004926:Escherichia coli / Q000276:immunology*; D005260:Female; D007111:Immunity, Cellular / Q000502:physiology; D007150:Immunohistochemistry / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013194:Staining and Labeling; D013601:T-Lymphocytes / Q000502:physiology; D016707:Tissue Fixation / Q000379:methods*