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The preparation and properties of macrophage-L cell hybrids
Abstract:
The plasma membrane of the mouse peritoneal macrophage has specific receptors which enable the cell to bind IgG or complement-coated sheep red cells and is also rich in a divalent cation-dependent adenosine triphosphatase (ATPase) activity. L cells lack these macrophage membrane markers. The question of macrophage membrane receptor expression was investigated in DBA/2 mouse macrophage x mouse LMTK(-) cell hybrids produced with the aid of Sendai virus. Three independent clones and one mass culture were isolated by their ability to grow in hypoxanthine, aminopterin, and thymidine (HAT) selection medium. These hybrids retained 85-100% of the sum of two parent cells' chromosomes and expressed several genes derived from both parents, including glucose phosphate isomerase isozymes and H-2 antigens. The hybrids displayed ATPase activity which was intermediate between that of the macrophage and L cell. The macrophage specific receptors for antibody or complement-coated red cells could not be demonstrated on hybrid cells. The selective absence of these receptors is probably because of a failure in gene expression rather than to loss of genes.
Insights
Mouse macrophage hybrids with L cells lack specific receptors for antibody or complement-coated red cells. This suggests a failure in gene expression, not gene loss, impacts receptor presence in these hybrid cells.
Area of Science:
- Cell Biology
- Immunology
- Genetics
Background:
- Mouse peritoneal macrophages possess specific receptors for IgG or complement-coated sheep red blood cells and exhibit divalent cation-dependent adenosine triphosphatase (ATPase) activity.
- Mouse L cells lack these characteristic macrophage membrane markers.
Purpose of the Study:
- To investigate macrophage membrane receptor expression in hybrid cells formed from mouse macrophages and mouse LMTK(-) cells.
- To determine if gene expression or gene loss is responsible for the absence of specific macrophage receptors in hybrid cells.
Main Methods:
- Generation of hybrid cells using Sendai virus fusion between DBA/2 mouse macrophages and mouse LMTK(-) cells.
- Isolation of hybrid clones using hypoxanthine, aminopterin, and thymidine (HAT) selection medium.
- Analysis of chromosome content, gene expression (glucose phosphate isomerase, H-2 antigens), ATPase activity, and receptor presence in hybrid cells.
Main Results:
- Hybrid cells retained a high percentage of parental chromosomes and expressed genes from both parent cells.
- Hybrid cells showed intermediate ATPase activity compared to parent cells.
- Macrophage-specific receptors for antibody or complement-coated red cells were not detected on the hybrid cells.
Conclusions:
- The selective absence of macrophage-specific receptors in the hybrid cells is likely due to a failure in gene expression.
- This finding suggests that gene regulation, rather than gene loss, is critical for the manifestation of these specific cell surface markers.