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The imino sugar N-butyldeoxynojirimycin (NB-DNJ) exhibits anti-HIV activity in vitro and inhibits the purified glycoprocessing enzyme alpha 1,2-glucosidase I. It has been speculated that the anti-viral activity of this compound may result from inhibition of HIV envelope glycoprotein processing. However, structural evidence that glucosidase inhibition takes place in intact cells at the anti-viral concentration (0.5 mM) is lacking. In this study, N-linked glycosylation of recombinant gp120 expressed in Chinese hamster ovary cells cultured in the presence or absence of NB-DNJ has been characterized. Immunoprecipitation, in conjunction with endoglycosidase H (endo H) digestion and SDS-polyacrylamide gel electrophoresis analysis, revealed that the glycosylation of gp120 was profoundly altered in the presence of NB-DNJ. The majority of the gp120 oligosaccharides from untreated cells were resistant to endo H. However, nearly complete endo H sensitivity was observed following treatment with 0.5 mM NB-DNJ indicating that gp120 expressed in treated cells carries immature, high mannose type oligosaccharides. In addition, using metabolic labeling with [3H]mannose, gel filtration chromatography, and digestion with highly purified glucosidases I and II, we provide the first definitive evidence that glucosidase I inhibition occurs at the anti-viral concentration of NB-DNJ. These data indicate that glucosidase inhibition is a candidate mechanism for the anti-viral activity of this compound.

A panel of mAbs has been generated which selectively, but not exclusively, recognizes populations of cells within germinal centers of immunized mice. All four mAbs stain B cell populations as defined by flow cytometry. The mAbs FH9.5 and C3.5 also stain T cell subsets (CD4+ and CD8+, respectively). Following density gradient centrifugation of spleen cells from immunized mice the majority of FH9.5+ and C3.5+ B cells are found in the low density, activated fractions. The cells bearing the epitope(s) recognized by the C6C3 and the A6A2 mAbs are less frequent, and from flow cytometric analysis the cells stained with these mAbs are B cells and myeloid cells. The surface markers defined by the four mAbs are not induced following mitogen stimulation of small resting B cells suggesting that these molecules are not general activation markers. Cell lines from a variety of hematopoietic lineages expressing the four markers have been identified. The cell surface molecule immunoprecipitated by the FH9.5 mAb is a polypeptide of 23-28 kDa. The C3.5 antigen is an 85- to 95-kDa protein. These mAbs will be useful in elucidating the complex events involved in B cell differentiation and maturation which occur within germinal centers.

The imino sugar, N-butyldeoxynojirimycin, is an inhibitor of the glycoprotein-processing enzyme glucosidase I and exhibits anti-(human immunodeficiency virus) activity in vitro. We have investigated the effect(s) of this compound on cell-surface glycoproteins by flow cytometry. We observed selective modulation of the transferrin receptor in response to treatment with 0.5 mM N-butyldeoxynojirimycin resulting in reduced cell-surface transferrin-receptor expression. The receptor modulation was dose dependent, resulted in reduced 59Fe uptake by treated cells and was fully reversible within 24 h of culture in the absence of the compound. Pulse/chase analysis in conjunction with endoglycosidase-H digestion demonstrated that transferrin-receptor glycosylation was altered following N-butyldeoxynojirimycin treatment, which is compatible with glucosidase inhibition. In addition, modulation of transferrin receptor in response to N-butyldeoxynojirimycin was not confined to a single cell line, but was also observed with certain human lymphoid and myeloid cell lines. Mechanism(s) of action of the imino sugar resulting in reduced cell-surface transferrin-receptor expression are discussed.

A method is described for the use of magnetic beads as a solid phase for the immunoprecipitation of labeled proteins. The anti-human transferrin receptor monoclonal antibody OKT-9 has been coupled to sheep anti-mouse IgG1-coated magnetic beads using the crosslinking agent dimethyl pimelimidate. The transferrin receptor is readily detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography following immunoprecipitation from 35S-labeled cell lysates. When compared with precipitations using OKT-9 coupled to protein G Sepharose the magnetic beads result in fewer nonspecific bands. The protocol described is generally applicable to the identification of labeled proteins. In addition, because magnetic beads are amenable to covalent crosslinking procedures they can be used for the purification of proteins from complex mixtures. Covalently crosslinked OKT-9 sheep anti-mouse IgG1-coated magnetic beads have been used to affinity purify unlabeled transferrin receptor from cell lysates giving comparable purity and yield to transferrin Sepharose isolated transferrin receptor. The major advantages offered by magnetic beads compared to conventional affinity matrices are low nonspecific binding and the rapidity with which the purification can be performed.

In observing more than 300 clinical interviews, we have seen a high frequency of physician-engendered defects. Most of the defective examples can be classified as one or a combination of five syndromes: the therapeutic lack; inattention to primary data (symptoms); a high control style; an incomplete data base usually omitting patient-centered data and active problems other than the present illness; and a thoughtless interview in which the physician fails to formulate needed working hypotheses. Proper diagnosis of these defects allows for better prescription of educational correction.

The illnesses of two patients with characteristic symptoms of subacute carbon monoxide poisoning were misdiagnosed initially. This resulted in the needless exposure of one patient and two relatives to a toxic environment. The cherry-red color of the skin commonly cited in the literature was absent in both patients. The carbon monoxide poisoning probably contributed to the myocardial infarction and pulmonary emboli seen in these patients. Vague flu-like illnesses should raise the suspicion of carbon monoxide poisoning.

Human follicular B cell lymphomas possess a t(14;18) interchromosomal translocation that juxtaposes the putative proto-oncogene bcl-2 with the immunoglobulin (Ig) heavy chain locus. We generated minigene constructs representing the bcl-2-Ig fusion gene found at this chromosomal breakpoint. These constructs were placed into the germ line of mice to assess the effects of the t(14;18) during development. The transgene demonstrates a lymphoid pattern of expression and uniformly results in an expanded follicular center cell population. Hyperplastic splenic follicles coalesce to form massive regions of splenic white pulp. Mice over 15 weeks of age demonstrate regional lymphadenopathy with abnormal cellular infiltrates. The expanded lymphoid compartment is composed predominantly of polyclonal B220-positive, IgM/IgD-positive B cells. Provocatively, the bcl-2-Ig transgene confers a survival advantage to a population of mature B cells assessed in vitro. bcl-2-Ig transgenic mice document a prospective role for the t(14;18) in B cell growth and the pathogenesis of follicular lymphoma.