IL-1-alpha and TNF-alpha differentially regulate CD4 and Mac-1 expression in mouse microglia.
The regulatory effects of the proinflammatory cytokines, interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) were investigated on CD4 and Mac-1 expression in mouse microglial cultures. The identity of the microglia in cultures was confirmed by multiple indices including morphology, uptake of acetylated low-density lipoprotein and lectin RCA 120 staining. Microglia growing on a monolayer of astrocytes (astrocyte-supported microglia) were both CD4- and Mac-1 positive (out of 94.5 % Mac-1-positive cells, 85.3% were also CD4 positive). When astrocyte-supported microglia were replated directly onto culture dishes (plate-supported microglia), the percentage of CD4- and Mac-1-positive cells decreased to 12-29 and 20-25% respectively. The addition of IL-1alpha or TNF-alpha to plate-supported microglia led to an upregulation of Mac-1 expression in a time- and dose-dependent manner with different EC50s (0.5 ng/ml for IL-1alpha and 2 ng/ml for TNF-alpha) but exhibited similar time-to-peak responses (over 12 h). The addition of IL-1alpha, but not TNF-alpha, also led to an increase in CD4 expression on plate-supported microglia with a similar dose response and time course. IL-1alpha treatment gave rise to an increase in the level of CD4 mRNA as assessed by RT-PCR. The possibility that cell proliferation was responsible for the observed effects on microglia was excluded by an analysis of 3H-thymidine incorporation. Our results suggest that cultured mouse microglia express CD4 molecules which can be upregulated by IL-1alpha while Mac-1 can be upregulated by both IL-1alpha and TNF-alpha.
Yu
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N
Department of Neuropharmacology, The Scripps Research Institute, La Jolla, Calif 92037, USA.
Zhang
X
X
Magistretti
P J
PJ
Bloom
F E
FE
D000818:Animals; D015704:CD4 Antigens / Q000096:biosynthesis*; D002478:Cells, Cultured; D005434:Flow Cytometry; D007375:Interleukin-1 / Q000494:pharmacology*; D016177:Macrophage-1 Antigen / Q000096:biosynthesis*; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects / Q000378:metabolism* / Q000821:virology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D015704:CD4 Antigens; D007375:Interleukin-1; D016177:Macrophage-1 Antigen; D014409:Tumor Necrosis Factor-alpha