Studies of the Epstein-Barr virus receptor found on Raji cells. I. Extraction of receptor and preparation of anti-receptor antibody

Raji, a human lymphoblastoid cell line, expresses a membrane receptor (EBVR) specific for Epstein Barr virus (EBV). A component that binds EBV was extracted from this cell line by treatment of the cells for 3 hr on ice with Tris buffer containing 10% glycerol. The treatment reduced the capacity of the cells to bind virus, and after concentration the receptor extract (RE) inhibited both EBV binding and superinfection of fresh Raji cells. Similarly prepared extracts of EBVR- cells lacked such activity. An antibody was made to the extract (anti-RE), which after absorption with EBVR- cells, bound to the same percentages of EBVR+ lymphoblastoid cell lines, EBVR+ human/mouse somatic cell hybrids, and fresh peripheral B cells as the virus did. In reciprocal assays, preincubation of EBVR+ cells with anti-RE inhibited virus binding. Doubly stained patches were observed on membranes of EBVR+ cells that had been incubated simultaneously with virus and anti-RE and stained respectively with rhodaminated and fluoresceinated reagents. The major polypeptide immunoprecipitated by anti-RE from radiolabeled Raji cells had an approximate calculated m.w. of 150,000.

Studies of the Epstein Barr virus receptor found on Raji cells. II. A comparison of lymphocyte binding sites for Epstein Barr virus and C3d

A comparison was made between the binding sites of two receptors that are believed to be closely associated on human B lymphocytes: complement receptor type two (CR2) that is specific for C3d fragments, and the receptor (EBVR) for Epstein Barr virus (EBV). Isolated fluid-phase CR2 bound to C3d on erythrocytes (EC3d) and inhibited both B cell-EC3d rosettes and the agglutination of EC3d by anti-C3d, it failed to inhibit either the binding or superinfection of B cells by EBV. By contrast, isolated fluid-phase EBVR inhibited EBV B cell binding activity and superinfection but had no CR2 activity. In addition, radiolabeled CR2 bound to EC3d and anti-CR2-Sepharose, whereas radiolabeled EBVR did not. Purified fluid-phase C3d fragments inhibited EC3d rosette formation with CR2+/EBVR+ cells but did not inhibit EBV binding. However, EBV binding to B cells did inhibit EC3d rosette formation. Clones of human/mouse somatic cell hybrids made from CR2+/EBVR+ human B lymphoblastoid cell and CR2-/EBVR- mouse myeloma cell parents expressed either EBVR or CR2 but only rarely expressed both EBVR and CR2. This suggested that the genes for EBVR and CR2 were located on two different human chromosomes. Thus it was concluded that CR2 is probably not the binding site for EBV.

Distribution of the core histones H2A.H2B.H3 and H4 during cell replication

The distribution of newly synthesized core histones H2A, H2B, H3 and H4 relative to the DNA strand synthesized in the same generation has been examined in replicating Chinese Hamster ovary cells. Cells are grown for one generation in [14C]-lysine and thymidine, and then for one generation in [3H]-lysine and 5-bromodeoxyuridine (BrUdRib) and a further generation in unlabeled lysine and thymidine. This protocol produces equal amounts of unifilarly substituted and unsubstituted DNA. Monomer nucleosomes isolated from chromatin containing these two types of DNA can be distinguished by crosslinking with formaldehyde and banding to equilibrium in CsCl density gradients. The results indicate that the core histones are equally distributed between the two types of DNA. These findings are discussed in terms of current models for chromatin replication; they do not support any long term association of newly replicated histones with either the leading or lagging side of the replication fork.

Isolation and characterization of cyanogen bromide fragments of the A and B chains of the antitumor toxin ricin D

Both the A and B chains of ricin D consist of four CNBr fragments. These fragments have been isolated from the separated chains of S-carboxymethylated ricin D obtained from the small bean variety of Ricinus communis. The peptides have been characterized by molecular weight, amino acid composition and amino terminal sequence. A unique order of the peptides is evident for each chain. These sequence data are compared with those obtained for ricin D isolated from the large bean variety.

Custom-fitted appliances for intestinal fistulas

A method for containing troublesome intestinal stomas or fistulas in open wounds is described. Custom-fitted faceplates are made using alginate materials and vulcanizing silicone rubber at room temperature. Three patients have been presented illustrating the rehabilitation and palliation that can be achieved by collaborative interaction between surgeons, enterostomal therapists, and prosthetic technicians.

Black light induction of skin tumors in mice

Albino inbred mice (A/J strain exposed to 40-w black light fluorescent lamps (BLB) for 12 hr a day for up to a year developed inflammatory and hyperplastic responses on hairless ear and tail skin, but not on back skin covered by hair. After 1 year of such exposure, many individuals developed papillomas, carcinomas, and sarcomas on their ears and tails. It may be concluded that black light is a skin carcinogen for A/J mice.