In the present study, we attempted to clarify what kind of adhesion molecules and tumor cytotoxic killer activity A-NK cells can express, when cultured for long period in vitro, and then tried experimentally to augment the selective accumulation the A-NK cells into rat mammary tumors, in combination with the prior injection of various kinds of adjuvants into the tumor region. The mechanisms by which the effector cells accumulate in tumor tissue will be discussed.
1. Animals: Specific pathogen-free (SPF) female rats. 2. Preparation of A-NK cells: A-NK cells were isolated from splenic lymphocytes. 3. Antibodies: Monoclonal antibodies, and Anti adhesion molecule antibodies. 4. Immunohistochemical staining and Flow cytometric analysis. 5. Preparation of mammary tumor bearing rats.
Immunocytochemical and flow-cytometric analysis revealed that most of the A-NK cells strongly expressed lymphocyte-function-associated antigen 1 throughout the incubation. All A-NK cells from 8-150-day cultures, particularly those cultured for 8 days, showed significant cytolytic activity against all targets. Peritumoral injection of various kinds of adjuvant, particularly Freund's complete adjuvant plus bacillus Calmetee-Guerin, resulted in a marked accumulation of A-NK cells in mammary tumor tissues 24 h after injection, and simultaneously in the formation of vessels resembling high-endothelium venules, and expression of the ICAM-1 molecule on the tumor cells in the sites of tumor tissues. When A-NK cells were intravenously administered, significant retardation of tumor growth and prolongation of survival of tumor-bearing rats were observed in the groups that received the prior injection of adjuvants.
These results indicate that the prior injection of proper adjuvant into the peritumoral region is effective for the selective accumulation or infiltration of A-NK cells into the sites of tumor tissues, and results in the marked retardation of tumor growth.
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Legal entity responsible for the study
School of Rehabilitation Sciences
The author has declared no conflicts of interest.