title: Kinetics of the early recruitment of leukocyte subsets at the sites of tumor cells in the lungs: natural killer (NK) cells rapidly attract monocytes but not lymphocytes in the surveillance of micrometastasis.
abstract: Early host defense mechanisms play a critical role for the outcome of metastatic disease but most of the initial steps of such responses against tumor cells are still unknown. Here, the specificity and kinetics of leukocyte subsets in response to intravenous inoculation of vital dye labeled Fischer 344 rat syngeneic MADB106 tumor cells were monitored in lungs in situ by immunohistochemistry and image analysis over a time-period of 6 hr. In comparison with sham injections, tumor cell inoculation induces a dynamic sequence of rapidly increasing granulocyte (+40% at 5 min), NK and T cell (+60% at 15 min) as well as monocyte (+100% at 30 min) numbers in lung tissue. Already within the first minutes frequent colocalizations of granulocytes and NK cells with tumor targets were found in situ. Within the first hour NK cells selectively kill tumor targets, because depletion of NK cells in vivo drastically increases both the number of MADB106 cells retained in lungs and the emerging numbers of lung tumor colonies. In addition, the tumor-cell-induced increase of monocytes strictly depends on the presence of NK cells because NK-depletion completely abrogates the time specific response of monocytes. Under NK depleted conditions the tumor-induced recruitment of CD4(+) T cells is more pronounced suggesting a compensatory mechanism. In contrast, B cell numbers progressively decrease within hours after cell inoculation. These findings demonstrate that NK and T cells mediate the initial steps in the surveillance of lung metastasis. NK cells rapidly kill tumor cells and subsequently recruit monocytes in vivo.
authors.affiliation: Department of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Shingu
authors.forename: Andreas
authors.initials: A
authors.lastname: Helfritz
authors.forename: Susanne
authors.initials: S
authors.lastname: Kuhlmann
authors.forename: Margot
authors.initials: M
authors.lastname: Zielinska-Skowronek
authors.forename: Roland
authors.initials: R
authors.lastname: Jacobs
authors.forename: Reinhold E
authors.initials: RE
authors.lastname: Schmidt
authors.forename: Reinhard
authors.initials: R
authors.lastname: Pabst
authors.forename: Stephan
authors.initials: S
authors.lastname: von Hörsten
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology* / Q000473:pathology; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001896:Boron Compounds / Q000494:pharmacology; D002465:Cell Movement; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007124:Immunoenzyme Techniques; D007275:Injections, Intravenous; D007694:Killer Cells, Natural / Q000276:immunology*; D008175:Lung Neoplasms / Q000276:immunology* / Q000473:pathology; D008212:Lymphocyte Depletion; D016131:Lymphocyte Subsets / Q000502:physiology; D008297:Male; D009000:Monocytes / Q000276:immunology*; D009368:Neoplasm Transplantation; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014407:Tumor Cells, Cultured
chemical_list: D001896:Boron Compounds; D005452:Fluoresceins; D005456:Fluorescent Dyes; D011838:Radiation-Sensitizing Agents; C024098:6-carboxyfluorescein; C057909:monoaminocarboxydihydroborane