Related Experiment Videos
Cloned cell lines with natural killer activity. Specificity, function, and cell surface markers
Abstract:
Cell lines with natural killer (NK) activity grown from native spleen cells cultured in medium conditioned by spleen cells proliferating in the presence of concanavalin A (Con A) were characterized. One NK cell line was cloned and assayed on several human and mouse NK-sensitive targets to analyze whether target specificities segregate upon cloning. Results showed that NK clones display target specificities identical to NK cells in normal spleen. This suggests that NK cells have no clonally distributed specific receptors to a given target. They may, however, have receptors which recognize identical antigens on all NK-sensitive targets or may possess multiple receptors for different target specificities. NK lines could not be demonstrated to possess activity in antibody-dependent cell-mediated cytotoxicity, nor did they effect mutual lysis. In the presence of Con A, NK cells exhibited dramatically enhanced lysis of NK-sensitive targets but only a slight increase in lysis of NK-insensitive targets. This indicates that the degree of lysis of an NK target is a function of two variables: effector binding to the target and target sensitivity to lysis. Furthermore, it suggests that the affinity of the putative antigen receptors on NK effectors must be rather weak. Cell surface marker analysis reveals that NK cell lines are Thy 1.2+, Lt-1-2-, T200+, asialo GM1+, and asialo GM2+. These markers distinguish NK cells from cytolytic thymus-derived lymphocytes, without resolving the question of classification within a give hematopoietic cell lineage.
Insights
Natural killer (NK) cell clones exhibit target specificities identical to normal spleen NK cells, suggesting a lack of clonally distributed specific receptors. This implies NK cells may recognize common antigens or possess multiple receptors for diverse targets.
Area of Science:
- Immunology
- Cell Biology
Background:
- Natural killer (NK) cells are crucial for innate immunity, mediating lysis of target cells.
- Understanding NK cell specificity and receptor mechanisms is key to their functional characterization.
Purpose of the Study:
- To characterize NK cell lines derived from spleen cells.
- To investigate if target specificities segregate upon cloning of NK cell lines.
- To analyze the functional properties and cell surface markers of NK cell lines.
Main Methods:
- Culturing spleen cells in conditioned medium with concanavalin A (Con A).
- Cloning NK cell lines and assaying their cytotoxic activity against various human and mouse targets.
- Performing cell surface marker analysis (Thy 1.2, Lt-1-2, T200, asialo GM1, asialo GM2).
Main Results:
- NK cell clones displayed target specificities identical to normal spleen NK cells.
- NK cell lines did not show activity in antibody-dependent cell-mediated cytotoxicity or mutual lysis.
- Concanavalin A (Con A) significantly enhanced lysis of NK-sensitive targets, indicating effector binding and target sensitivity are key variables.
Conclusions:
- NK cells likely lack clonally distributed specific receptors, potentially recognizing common antigens or multiple target specificities.
- NK cell lysis is dependent on effector-target binding and target sensitivity, with relatively weak putative antigen receptor affinity.
- Cell surface marker analysis distinguished NK cells from cytolytic thymus-derived lymphocytes, aiding in their classification within hematopoietic lineages.