Ultrastructural localization of peanut lectin binding to extravascular white blood cells in the bone marrow of embryonic chicks.

Labelling by the galactose-specific lectin peanut agglutinin was studied in bone marrow of the embryonic chick at the electron-microscopic level by use of both a gold-conjugated lectin and an indirect, ferritin-conjugated, biotinylated lectin. Cell surface labelling is exclusively restricted to developing and mature heterophilic granulocytes, monocyte/macrophages, mast cells/basophils, all of which appear to develop and reside in the extravascular spaces of the bone marrow. Resident small lymphocytes, which comprise a minor portion of the cell population, are also labelled. Erythroid cells and thrombocytic cells, which develop inside venous sinusoidal vessels, display no labelling. The latter cells, like extravascular leukocytes, contain surface galactosyl residues located in subterminal positions on cell surfaces, since they are labelled by the galactose-specific Ricinus communis agglutinin-I. It is postulated that terminal galactosyl residues might be involved in interactions between the surfaces of extravascular leukocytes and extracellular matrix and/or stromal cell surfaces.

Human cellular immune response to copolymer I and myelin basic protein.

Copolymer I (Cop I) is being tested as a treatment for MS because it protects animals against experimental allergic encephalomyelitis, and because there is immunologic cross-reactivity reported between Cop I and myelin basic protein (MBP). From the peripheral blood mononuclear cells of four normal individuals, we isolated helper-phenotype T-cell lines that reacted in vitro with Cop I or MBP. Cop I-reactive cell lines did not respond to MBP, nor did MBP-reactive T-cell lines respond to Cop I. Antigen-specific immune tolerance was induced in MBP-reactive cell lines by exposure to MBP in vitro, but similar exposure to Cop I did not induce tolerance in the MBP-reactive cell lines. We found no evidence of immunologic cross-reactivity between Cop I and MBP.

Immunological responsiveness of maternal and foetal lymphocytes during normal pregnancy in the ewe.

Peripheral blood lymphocytes collected from ewes before and during pregnancy manifested constant reactivity to concanavalin A and to paternal and third party peripheral blood lymphocytes. However, in some instances, the reactivity of these maternal cells against lipopolysaccharide and lymphatic lymphocytes from paternal, foetal and third-party donors increased markedly during pregnancy. Apart from an indication that plasma from some pregnant ewes acquired the capacity to depress lymphocyte reactivity non-specifically, no evidence was obtained to suggest that maternal lymphocyte reactivity observed in vitro did not accurately reflect the capacity of these cells in the donor ewe. In particular, there was no indication that populations of maternal peripheral blood lymphocytes returning from the gravid uterus had undergone any modification of reactivity against foetal determinants.

Immunoglobulins on the surface of lymphocytes in ontogeny.

Immunoglobulins on the surface of lymphocytes from pig foetuses and newborn precolostral piglets were studied using iodinated monospecific anti-pig gamma- or mu-antisera. Labelling of cells was determined by autoradiography in light and electron microscope. Beginning with the 80th day of gestation the lymphocytes with surface IgM were detected in significant amounts in the spleen, whereas at earlier stages of prenatal development the IgM-bearing lymphocytes were detected rarely. The cells which carry surface immunoglobulins were classified as small lymphocytes with typical ultrastructural morphology.