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Inducible and constitutive MHC class II gene expression. Distinct tissue-specific genetic controls
S Sartoris1, M T Scupoli, L Scarpellino
1Istituto di Scienze Immunologiche, Facoltà di Medicina e Chirurgia, Università di Verona, Italy.
Journal of Immunology (Baltimore, Md. : 1950)
|September 15, 1990
Summary
Human B cells can confer constitutive MHC class II antigen expression to macrophages in somatic cell hybrids. This dominant trait suggests novel regulatory mechanisms for immune gene expression.
Area of Science:
- Immunology
- Cell Biology
- Genetics
Background:
- B cells constitutively express MHC class II antigens, while macrophages require induction.
- Understanding the regulation of MHC class II expression is crucial for immune responses.
Purpose of the Study:
- To investigate the genetic control of MHC class II antigen expression in interspecies somatic cell hybrids.
- To determine if human B cell factors can induce constitutive MHC class II expression in macrophages.
Main Methods:
- Created interspecies somatic cell hybrids between human B cells (Raji) and murine macrophages (P388 D1).
- Analyzed hybrids using phenotypic, molecular, and karyotype analysis to assess MHC class II gene expression.
- Investigated the role of human chromosomes in regulating murine MHC class II expression.
Main Results:
- Murine macrophage MHC class II genes were constitutively expressed in hybrids under human B cell control.
- Expression resulted from de novo mRNA accumulation, indicating transcriptional activation.
- Reversion to MHC class II-negative phenotype correlated with human chromosome segregation.
Conclusions:
- Constitutive MHC class II gene expression is a dominant trait in B cell x macrophage hybrids.
- Human B cell genome can activate transcription of murine MHC class II genes.
- Suggests differential regulatory mechanisms controlling MHC class II expression during cell differentiation.