Differential affinity of murine lymphocyte membrane IgM and IgD for the lentil lectin

The separation of immunocyte subpopulations by use of various lectins

The use of lectins for the enrichment of various lymphocyte subpopulations was investigated. Bauhinia purpurea lectin (BPA) was found to be effective for the enrichment of B cells, and the B cells thus obtained were further fractionated with lentil lectin into subsets showing high and low responses to dextran sulfate. The ability of various lectins to selectively induce suppressor T cell activity or helper T cell activity was also examined. The suppressor T cells thus induced were enriched peanut lectin and, conversely, the helper T cells were enriched with Limulus polyhemus lectin. This method was applied to analysis of age-dependent changes in the levels of suppressor and helper T cells in autoimmune-prone mice. Cytotoxic T cells induced in an allogeneic mixed lymphocyte culture were enriched with Dolichos biflorus lectin (DBA). These cytotoxic T cells showed a specific killing effect in vitro. However, when spleen cells of tumor-bearing mice were fractionated by use of DBA, the DBA- cells mediated the regression of the tumors in vivo. BPA was also found to be effective for the enrichment of the interleukin-2-producing T cell subset and macrophage precursor cells. Using this technique, bone marrow cells of autoimmune-prone MRL/1 mice were found to be rich in macrophage precursor cells.

Lectin-binding patterns of small lymphocytes in bone marrow, thymus and spleen: demonstration of lymphocyte subsets by quantitative radioautography

Cells from mouse bone marrow, thymus and spleen were exposed to 125I-labeled concanavalin A (Con A). Lens culinaris lectin (LCL), soybean agglutinin (SBA), Helix pomatia agglutinin (HPA), phytohemagglutinin-P (PHA-P), peanut agglutinin (PNA), or wheat germ agglutinin (WGA) in a range of concentrations and examined radioautographically. Small lymphocytes in the three organs differed in the minimal concentration of each lectin which gave detectable surface labeling, while at optimal lectin concentrations, their labeling intensity profiles differed markedly. Inhibition by sugars demonstrated the labeling specificity. Major populations of bone marrow small lymphocytes bound WGA strongly, while Con A, SBA, HPA, PHA-P and LCL were bound only weakly, and PNA binding was lacking. Most thymus cells bound Con A, SBA, HPA, PHA-P and PNA strongly, WGA and LCL weakly. Subsets of bone marrow and thymus small lymphocytes differed from the major populations in their lectin-binding intensities. Spleen small lymphocytes were heterogeneous in the binding of each lectin. However, a major population bound LCL exceptionally strongly, while few cells bound PNA. Using a panel of lectins under standardized conditions, these studies show distinctive lectin-binding patterns for small lymphocytes in the bone marrow, thymus and spleen, respectively. Major and minor cell populations are distinguishable in each organ, providing an approach to discriminating lymphocyte lineages, subtypes and differentiation stages.

Radioiodination of surface proteins and glycoproteins of lymphocytes by immobilized lactoperoxidase

Radioiodination of lymphocyte surface proteins employing soluble lactoperoxidase was found to be unsatisfactory for the quantitative isolation and characterization of cell surface glycoproteins: either the glycoproteins were contaminated by self-iodinated lactoperoxidase or were in part removed by the washing step following the radioiodination procedure. Therefore, optimal conditions for cell surface radioiodination by lactoperoxidase covalently linked to Sepharose 4B (lacto-beads) were worked out. By the employment of immobilized lactoperoxidase, the enzyme could easily be removed following solubilization of the radiolabelled cells by a simple washing step. Radioiodinated cell surface proteins and glycoproteins were obtained without any loss as shown by SDS polyacrylamide gel electrophoresis.