Gerd Walz

CD62/P-selectin recognition of myeloid and tumor cell sulfatides

CD62, also called PADGEM protein, GMP-140, or P-selectin, is a granule membrane protein of endothelial cells and platelets that is mobilized to the plasma membrane following exposure to mediators such as thrombin, histamine, complement components, or peroxides. Data presented to date suggest that one ligand of CD62 includes CD15 (Lewis x determinant) and sialic acid. We show here that sulfatides, heterogeneous 3-sulfated galactosyl ceramides, are an apparently unrelated ligand of CD62. Sulfatides are expressed on the plasma membrane of, and are excreted by, granulocytes, and constitute the principal ligand for CD62 on the plasma membrane of some tumor cells. CD62 binds to sulfatides adsorbed to plastic as avidly as it binds to myeloid or tumor cells. We find that granulocytes excrete sulfatides at a rate predicted to allow them to be rapidly released from CD62 once they have exited the bloodstream.

Tumor necrosis factor-α, interleukin-1β, and interleukin-6 expression in inflammatory bowel disease

The etiology of ulcerative colitis (UC) and Crohns disease (CD) remains enigmatic. Infiltrating intestinal macrophages are capable of producing the proinflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). We investigated the presence of IL-6, TNF-α and IL-1β mRNA transcripts in inflammatory bowel disease (IBD), normal, and other inflammatory intestinal specimens utilizing the polymerase chain reaction (PCR). TNF-α mRNA levels did not vary between inflammatory bowel disease and control specimens. IL-1β mRNA levels were highest in active UC and noninflammatory bowel disease inflammatory specimens while IL-6 mRNA levels were highest in active IBD specimens. Infiltrating T cells, macrophages, and B cells were identified as sources of IL-6 protein in inflammatory bowel disease specimens by immunofluorescent staining. IL-6 transcripts were elevated only in active inflammatory bowel disease specimens, suggesting that IL-6-mediated immune processes are ongoing in the inflammatory mucosal environment of CD and UC.

Physiologic signaling in normal human T-cells: mRNA phenotyping by northern blot analysis and reverse transcription-polymerase chain reaction☆

Synergy between ionomycin and sn-1,2-dioctanoylglycerol (diC8) was shown at the level of lymphokine gene transcription. Transcriptional activation of interleukin-2 (IL-2), interferon-gamma (IFN-gamma), and the protooncogene H-ras was accomplished by signaling highly purified normal human resting T-lymphocytes (T-cells) with diC8, a physiologic regulator of protein kinase C, and the calcium ionophore, ionomycin. Northern blot analysis of mRNA for early T-cell activation genes demonstrated the synergism between diC8 and ionomycin at the gene induction level. To amplify very low levels of IL-2 mRNA, sequential reverse transcription and polymerase chain reaction (RT-PCR) of T cell mRNA were used to demonstrate the capacity of the calcium signal (ionomycin) to promote low-level IL-2 transcription in normal human T-cells without additional signals. Cyclosporine (CsA) prevented diC8 and ionomycin-induced expression of IL-2, IFN-gamma, and H-ras genes. The completeness of its inhibitory effect was evident by the absence of IL-2 transcripts in CsA-treated cultures screened by the RT-PCR technique. CsA also prevented IL-2 and IFN-gamma gene expression in accessory cell-depleted T-cells stimulated by cross-linking the CD2 and CD3 antigens on the cell surface. Our observations demonstrate that a physiologic regulator of PKC, diC8, and cell surface crosslinking of the CD2 and CD3 antigen, promote gene expression in normal human quiescent T-cells independently of accessory cells, and that CsA prevents gene expression via a direct effect on T-cells.