In human fetal astrocytes exposure to interleukin-1 beta stimulates acquisition of the GD3+ phenotype and inhibits cell division.
In human astrocyte cultures established from second-trimester fetal brain tissue, approximately 5-10% of total astrocyte population in unstimulated cultures were GD3+/glial fibrillary acidic protein (GFAP)+. The GD3+ cells were always GFAP+ and grew as flat, highly spread cells but changed to process-bearing cells after interleukin-1 beta (IL-1 beta) stimulation. It is interesting that IL-1 beta, a known mitogen for rat astrocytes, suppressed human fetal astrocyte proliferation as determined by [3H]thymidine incorporation, bromodeoxyuridine (BrdU) labeling, and cell counting. The GD3+ population, however, consistently increased in absolute number after IL-1 beta stimulation, in a dose- and time-dependent manner. The IL-1 beta-mediated increase in number of GD3+ astrocytes was independent of initial cell density or serum concentration. By flow cytometry, IL-1 beta enhanced both the mean fluorescence intensity and the percentage of GD3+ cells. To investigate whether the increase in GD3+ astrocyte cell number was due to proliferation of preexisting GD3+ astrocytes or due to conversion of GD3- to GD3+ cells, we performed BrdU/GD3 double immunocytochemistry. BrdU/GD3 double-positive cells were extremely rare in both control and IL-1 beta-stimulated cultures. Moreover, an increase in number of GD3+ astrocytes was still observed in control and IL-1 beta-stimulated cultures were GD3+ cells had been initially eliminated by cell sorting. These results indicate that GD3+ astrocytes in human fetal culture may represent a postmitotic, differentiated, distinct phenotype.
Lee
S C
SC
Department of Pathology (Neuropathology), Albert Einstein College of Medicine, Bronx, New York 10461.
Liu
W
W
Dickson
D W
DW
Brosnan
C F
CF
D001253:Astrocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D001790:Blood Physiological Phenomena; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology; D005333:Fetus / Q000166:cytology / Q000502:physiology*; D005732:Gangliosides / Q000378:metabolism*; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D010641:Phenotype
D016207:Cytokines; D005732:Gangliosides; D007375:Interleukin-1; C026226:ganglioside, GD3