Fetal bovine serum contains an inhibitor of interleukin-1.
The keratinocyte cell line COLO-16 constitutively produces factors with interleukin-1 (IL-1) activity including IL-1 alpha and IL-1 beta. IL-1 activity assayed by thymocyte proliferation from cell supernatants was 20-50% less if cells were maintained in media containing 10% fetal bovine serum (FBS) compared to media without serum 24 h prior to harvest. The increased IL-1 activity in supernatants from cells in serum free media was not due to increased cellular levels of IL-1 alpha or IL-1 beta mRNA. Similarly, IL-1 activity recovered from conditioned supernatants of COS cells transfected with expression vectors containing IL-1 beta cDNA was approximately 22-45% less in cells grown in 20% FBS medium compared to similar cultures grown for 3 days post transfection in 1% FBS. When serial dilutions of recombinant IL-1 were made in buffer containing 10% FBS and assayed by a thymocyte proliferation method, a 30-50% decrease in activity was observed. IL-1 activity was also measured by its ability to induce prostaglandin E2 synthesis by fibroblasts. When COS conditioned supernatants were applied to fibroblast cultures there was 30% less prostaglandin E2 activity from fibroblasts treated with COS supernatants containing 20% FBS, compared to supernatants containing 1% FBS. The inhibitor molecule was partially purified by gel filtration and found to have a molecular weight of approximately 85,000. The presence of FBS in cell-conditioned media significantly reduces the sensitivity of IL-1 detection by bioassay techniques.
Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
R C
RC
McKenzie
C B
CB
Harley
S
S
Matic
D N
DN
Sauder
D000818:Animals; D001798:Blood Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D002417:Cattle; D002850:Chromatography, Gel; D015232:Dinoprostone / Q000096:biosynthesis; D005312:Fetal Blood; D006801:Humans; D007375:Interleukin-1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D008970:Molecular Weight; D010957:Plasmids / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins; D013601:T-Lymphocytes / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured
D001798:Blood Proteins; D007375:Interleukin-1; D012333:RNA, Messenger; D011994:Recombinant Proteins; D015232:Dinoprostone