Monoclonal antibodies directed against the sugar sequence of lacto-N-fucopentaose III are obtained from mice immunized with human tumors

Four hybridomas obtained from mice immunized with human adenocarcinomas of colon or stomach produce antibodies that bind specifically in solid-phase radioimmunoassay to the ceramide pentasaccharide that contains the lacto-N-fucopentaose III sequence of sugars. Binding of the antibodies to the glycolipid is inhibited by lacto-N-fucopentaose III,

but not by structurally related oligosaccharides. The antibodies bind to glycolipids of erythrocytes, granulocytes, and certain normal and malignant tissues.     

Interleukin-5, interleukin-3, and granulocyte-macrophage colony-stimulating factor cross-compete for binding to cell surface receptors on human eosinophils.

Human interleukin (IL)-5 receptors were characterized by means of binding studies using bioactive 125I-labeled IL-5. Of purified primary myeloid cells, eosinophils and basophils but not neutrophils or monocytes expressed surface receptors for IL-5. Binding studies showed that eosinophils expressed a single class of high affinity receptors (Ka = 1.2 x 10(10) M-1) with the number of receptors being small (less than 1000 receptors/cell) and varying between individuals. Among several cell lines examined only HL-60 cells showed detectable IL-5 receptors which were small in numbers (200 receptors/cell) and also bound 125I-IL-5 with high affinity. The binding of IL-5 was rapid at 37 degrees C while requiring several hours to reach equilibrium at 4 degrees C. Specificity studies revealed that the two other human eosinophilopoietic cytokines IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) inhibited the binding of 125I-IL-5 to eosinophils. No competition was observed by other eosinophil activating or nonactivating cytokines. The inhibition of 125I-IL-5 binding by IL-3 and GM-CSF was partial up to a concentration of competitor of 10(-7) M with GM-CSF consistently being the stronger competitor. Converse experiments using IL-5 as a competitor revealed that this cytokine inhibited the binding of 125I-IL-3 and of 125I-GM-CSF in some but not all the individuals tested, perhaps reflecting eosinophil heterogeneity in vivo. Cross-linking experiments on HL-60 cells demonstrated two IL-5-containing complexes of Mr 150,000 and Mr 80,000 both of which were inhibited by GM-CSF. The competition between IL-5, IL-3, and GM-CSF on the surface of mature eosinophils may represent a unifying mechanism that may help explain the common biological effects of these three eosinophilopoietic cytokines on eosinophil function. This unique pattern of competition may also be beneficial to the host by preventing excessive eosinophil stimulation.     

Epstein-Barr virus in nontumorigenic and tumorigenic nasopharyngeal carcinoma (NPC) somatic cell hybrids

Somatic cell hybrids between mouse fibroblasts and human cells derived from nasopharyngeal carcinoma (NPC) biopsies or NPC tumors propagated in nude mice were examined for the expression of the Epstein-Barr nuclear antigen (EBNA), retention of Epstein-Barr viral (EBV) DNA, and tumorigenicity in nude mice. In all hybrids the expression of EBNA correlated with the detection of EBV-DNA. After more than 2 years in culture, the hybrids examined retained similar amounts of EBV-DNA when compared to previously published data. Retention of EBV-DNA did not correlate with the presence of any particular human chromosome. Use of either rodent cell lines, clone 1D or IT-22, did not affect the retention nor loss of EBV-DNA. For tumorigenicity studies, NPC cells were fused with IT-22 cells and injected into nude mice. Tumor formation did not depend on the presence or absence of EBNA and detectable EBV-DNA sequences; tumorigenicity in these studies could not be correlated with the presence of any particular human chromosome or the origin of the NPC biopsy.     

Evidence for a cerebral cholinergic system and suggested pharmacological patterns of neural organization in the prostomium of the polychaete Nereis virens (SARS)

The histological visualization of choline acetyltransferase (CAT) and acetylcholinesterase (AChE) on frozen sections of prostomia of Nereis virens indicate a concentration of cholinergic activity in the anterior brain. Components are probably sensory epithelial cells with cholinergic axons entering the brain in cephalic nerves and efferent cholinergic axons to prostomial muscle leaving the brain in the same nerves. There are also subepidermal cholinergic cells that may be second order motor neurons serving epidermal mucous cells. The smaller, second lobe of the corpora pedunculata and its associated vertical fibre tract are CAT⁴ and appear continuous, on each side of the cerebral ganglion, with a dorsal and a ventral longitudinal bundle of AChE⁺ fibers. This system tapers to nothing at the level of the posterior eyes. There is a small AChE⁺ component to each optic nerve and AChE is present in the nuchal epithelium. These observations are discussed in relation to earlier studies on aminergic and neurosecretory activity in the same ganglion.     

Aberrant double replication of segments of chromosomal DNA following DNA synthesis inhibition by cytosine arabinoside.

Using two different cell lines growing logarithmically, it is demonstrated that inhibition of DNA synthesis by cytosine arabinoside leads to a disruption of the sequence of replication of the chromosomal DNA. After release of the inhibition, some DNA synthesis is reinitiated in DNA segments replicated earlier in that S phase, leading to double replication of some DNA segments. This was directly demonstrated by showing that, following removal of the inhibitor, DNA was synthesized off template strands which had themselves been synthesized only 1–2 h before the addition of the inhibitor.     

The human Ia system: Definition and characterization by xenogeneic antisera

The production of xenogeneic anti-Ia serum against Ia antigens in serum has been previously described in the mouse and we now describe the production of xenogeneic anti-human Ia antisera using similar methods. With an indirect resetting technique, Ia-like antibodies were shown to react with the majority of B cells (95%), a subpopulation of T cells, with carbonyl iron adherent cells, and with some E^–Ig^– null cells, but there was no reaction with red cells and platelets. These reactions were the same as those obtained with DRW antisera using cytotoxicity testing. In addition, antigens detected with xenogeneic antisera were also found in serum, where they were found to exist in a low molecular weight, dialyzable form. By the selective removal of different cell surface markers by cocapping, no association could be found with the specifities detected with the xenogeneic anti-Ia antisera and with surface Ig, ₂-microglobulin, or HLA-A and B specificities. Alloantibodies to DRW specificities (but not HLA-A, B specificities) were able to specifically block the binding of the rabbit anti-Ia antibodies to B cells, and reciprocal blocking of rabbit antisera by DRW antibodies was also observed. Several xenogenic antisera were produced by immunizing rabbits with the serum of different individuals. Each antiserum was shown to contain a number of different specificities, as they gave different reaction patterns with different individuals when testing was done both directly and by absorption. These xenogeneic anti-la sera also segregated in a family with HLA-A and B specificities. The detection of a polymorphic antigenic system segregating with the HLA complex, distinct from HLA-A and B specificities, and whose antigens occur predominantly on B cells is therefore described. Because of the similarity of the reactions of the xenogeneic antisera in man to those found in the mouse, and because of the close relationship to the DRW specificities, the system has been provisionally called the H.Ia system.Abbreviations used in this paper AET 2-aminoethyl isothiouronium bromide - ₂-M -2 microglobulin - BSA Bovine serum albumin - H.Ia Human Ia - HuRBC Human red blood cells - Ig Immunoglobulin - Ir Immune response - MHC Major histocompatibility complex - MLR Mixed lymphocyte reaction - NHS Normal human serum - NMS Normal mouse serum - PBL Peripheral blood lymphocytes - PBS Phosphate-buffered saline - RAHIg Rabbit anti-human immunoglobulin - RASIg Rabbit anti-sheep immunoglobulin - RFC Rosette-forming cells - SAHIg Sheep anti-human immunoglobulin - SARIy Sheep anti-rabbit immunoglobulin - SRBC Sheep red blood cells     

An NMR investigation of electron transfer in the copper-protein, plastocyanin.

1. The proton NMR spectra of oxidised and reduced French bean plastocyanin have been recorded on a 270 MHz pulsed spctrometer. 2. The spectrum of a mixture containing the protein in the paramagnetic Cu(II) and diamagnetic Cu(I) states is a superposition of the separate spectra. When ferrirate spectra. 3. The results show that self-exchange between Cu(II)- and Cu(I)-plastocyanin is slow on the NMR time scale (kex less than 2-10(4) M-1-s-1 at 50 degrees C), and that electron transfer in the presence of ferricyanide is rapid (k greater than 1-10(5) M-1-s-1).     

Chloroplast membranes of the green alga Acetabularia mediterranea. I. Isolation of the photosystem II.

1. In the presence of Triton X-100, chloroplast membranes of the green alga Acetabularia mediterranea were disrupted into two subchloroplast fragments which differed in buoyant density. Each of these fractions had distinct and unique complements of polypeptides, indicating an almost complete separation of the two fragments. 2. One of the two subchloroplast fractions was enriched in chlorophyll b. It exhibited Photosystem II activity, was highly fluorescent and was composed of particles of approx. 50 A diameter. 3. The light-harvesting chlorophyll-protein complex of the Photosystem II-active fraction had a molecular weight of 67 000 and contained two different subunits of 23 000 and 21 500. The molecular ratio of these two subunits was 2:1.