Andrew J. Hapel

The effects of colony-stimulating factor 1 (CSF-1), the primary regulator of mononuclear phagocyte production, are thought to be mediated by the CSF-1 receptor (CSF-1R), encoded by the c-fms proto-oncogene. To investigate the in vivo specificity of CSF-1 for the CSF-1R, the mouse Csf1r gene was inactivated. The phenotype of Csf1(-)/Csf1r(-) mice closely resembled the phenotype of CSF-1-nullizygous (Csf1(op)/Csf1(op)) mice, including the osteopetrotic, hematopoietic, tissue macrophage, and reproductive phenotypes. Compared with their wild-type littermates, splenic erythroid burst-forming unit and high-proliferative potential colony-forming cell levels in both Csf1(op)/Csf1(op) and Csf1(-)/Csf1r(-) mice were significantly elevated, consistent with a negative regulatory role of CSF-1 in erythropoiesis and the maintenance of primitive hematopoietic progenitor cells. The circulating CSF-1 concentration in Csf1r(-)/Csf1r(-) mice was elevated 20-fold, in agreement with the previously reported clearance of circulating CSF-1 by CSF-1R-mediated endocytosis and intracellular destruction. Despite their overall similarity, several phenotypic characteristics of the Csf1r(-)/Csf1r(-) mice were more severe than those of the Csf1(op)/Csf1(op) mice. The results indicate that all of the effects of CSF-1 are mediated via the CSF-1R, but that subtle effects of the CSF-1R could result from its CSF-1-independent activation.

It has been recently demonstrated that conditioned media from Con A-stimulated splenocyte cultures contain a novel lymphokine termed IL 3. IL 3 is characterized by its ability to induce 20-alpha-hydroxysteroid dehydrogenase in spleen cells from young nu/nu mice. In search of a convenient source for biochemical and in vivo studies of this lymphokine, a number of established murine cell lines were screened for the constitutive and induced production of Il 3. It was found that WEHI-3 cells, originally designated as a myelomonocyte cell line, produced high levels of IL 3 constitutively. Added mitogen and/or phorbol acetate did not enhance the production of IL 3. Production of IL 3 varied among various sublines of WEHI-3. IL 3 purified from WEHI-3-conditioned media has biochemical and biologic characteristics identical to those obtained from Con A-conditioned media. WEHI-3 conditioned media, however, generally contained 100-fold higher levels of IL 3 than conditioned media from Con A-stimulated splenic lymphocytes.

The authors have analysed gliadin specific, CD4+ T cells isolated from small intestinal biopsies of 23 adult coeliac disease patients (20 on a gluten-free diet and three untreated) and nine control patients. The biopsies were stimulated ex vivo with a peptic/tryptic digest of gliadin for 24 h, and activated T cells were positively selected with paramagnetic beads coated with an antibody against the interleukin-2 receptor. The T cells were expanded and tested for gliadin reactivity and HLA restriction. Gliadin specific, polyclonal T cell lines were recovered from biopsies of all 23 patients. Inhibition studies of T cell lines from 21 patients with anti-HLA monoclonal antibodies indicated predominant presentation of the gliadin antigen by HLA-DQ2 in T cell lines from 11 patients (lines from seven patients with complete MoAb inhibition, the remaining with incomplete inhibition) and incomplete inhibition by HLA-DR3 in lines from three patients. Nine gliadin specific T cell clones from six patients were established; all of these were HLA-DQ2 restricted. Gliadin specific T cells were not found in biopsies from the non-coeliac controls. Our findings demonstrate that gliadin reactive T cells are commonly found in the intestinal mucosa of CD patients and they support the notion that the majority of T cells recognize gliadin peptide(s) when presented by the disease associated DQ2 molecules.