Heterogeneity in surface glycoproteins of mouse peritoneal macrophage populations

Wheat-germ agglutinin binding in four types of mouse peritoneal macrophage

After stimulation of the mouse peritoneal cavity with newborn calf serum (NBCS), four types of monocyte and macrophage were distinguished on the basis of peroxidase (PO) patterns. These cell types showed heterogeneity in their binding of the lectin wheat-germ agglutinin (WGA). At 16 h after stimulation, monocytes and monocyte-derived macrophages (with PO activity in granules) had a high level of WGA binding; PO-negative macrophages showed moderate WGA binding, and resident macrophages (with PO activity in the RER and nuclear envelope) had low WGA binding. At later time-points after stimulation, each of these cell types lost WGA binding sites. This decrease was related to a process of differentiation and to a modulation, affected by environmental factors. The present results also indicated that PO-negative macrophages can give rise to resident macrophages. Whether these PO-negative cells are monocyte derived or originate otherwise needs further investigation. The fourth type of macrophage, the exudate-resident cell (with PO activity both in granules and in the RER and nuclear envelope), with a WGA binding pattern similar to that of monocytes and monocyte-derived macrophages, was considered not to be a resident precursor cell.

Differences in surface expression of WGA-binding proteins of cells from a lymphosarcoma and its liver metastases

The protein and glycoprotein compositions of a subcutaneous lymphosarcoma (1 degree) and its metastatic deposits in the liver (2 degrees) have been investigated in Triton X-100 extracts obtained from tissue, single cells and membrane preparations. No consistent differences in the electrophoretic patterns for 1 degree and 2 degrees tissue or cells were observed for separations visualized with the protein stain Coomassie Blue. Substantial and consistent reductions in the glycoprotein content of extracts from 2 degrees tissue or cells were observed if the separated proteins were treated with the radioiodinated lectin, Wheat Germ Agglutinin (WGA). Densitometric scans of autoradiographs indicated that WGA binding occurred in 4 major areas; the approximate mol. wts of these were 180,000, 102,000, 84,000 and 23,000 daltons. All these components except the 23,000 component were shown to be located in the cell membrane and to be reduced in 2 degrees preparations. Possible sources of host contamination were also investigated, but these did not show WGA binding patterns that were similar to that obtained for the tumour. If 2 degrees tumour was transplanted into the 1 degree site, the resultant growth exhibited a WGA-binding pattern normally shown by a 1 degree tumour growing in this site. Conversely, if 1 degree tumour was transplanted into the liver, the WGA binding of the resultant growth was substantially reduced. The results suggest that local and metastatic tumours do contain cells that express different glycoproteins on their surfaces but that the site of tumour growth is a very important factor in determining this difference in surface expression.