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Biomedical subjects

J D Kemp

Publications and source records attributed to J D Kemp.

At least 37 records · Page 2Linked to original sources
PubMed1992

Genetic and immunologic analysis of a family containing five patients with common-variable immune deficiency or selective IgA deficiency.

A family with 13 members included 2 subjects with selective IgA deficiency (IgA-D) and 3 subjects with common-variable immune deficiency (CVID), diseases which usually occur sporadically. Reciprocal combinations of B and T cells in vitro between one normal and two immune-deficient family members and normal subjects revealed that defective Ig synthesis was determined by the B cells, while the patient T cells functioned normally. Normal T helper and suppressor function was demonstrated even in one patient with CVID who developed a T-cell lymphoproliferative disorder associated with elevated IgM; this patient's B cells made only IgM in vitro. Immune deficiencies were inherited in this family in a pattern consistent with an autosomal dominant trait with incomplete penetrance. All the immune-deficient patients in this family possessed at least one copy of an MHC haplotype previously shown to be abnormally frequent in IgA-D and CVID: HLA-DQB1*0201, HLA-DR3, C4B-Sf, C4A-deleted, G11-15, Bf-0.4, C2-a, HSP70-7.5, TNF alpha-5, HLA-B8, and HLA-A1. The patient who developed the lymphoproliferative disorder was homozygous for this haplotype. Four immunologically normal members, one of whom was 80 years old, also possessed this MHC haplotype, indicating that its presence is not sufficient for disease expression. A small segment of another MHC haplotype associated with Ig deficiency in the population also occurred in this family, but it was not associated with immune deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Synthetic cryIIIA gene from Bacillus thuringiensis improved for high expression in plants.

A 1974 bp synthetic gene was constructed from chemically synthesized oligonucleotides in order to improve transgenic protein expression of the cryIIIA gene from Bacillus thuringiensis var. tenebrionis in transgenic tobacco. The crystal toxin genes (cry) from B. thuringiensis are difficult to express in plants even when under the control of efficient plant regulatory sequences. We identified and eliminated five classes of sequence found throughout the cryIIIA gene that mimic eukaryotic processing signals and which may be responsible for the low levels of transcription and translation. Furthermore, the GC content of the gene was raised from 36% to 49% and the codon usage was changed to be more plant-like. When the synthetic gene was placed behind the cauliflower mosaic virus 35S promoter and the alfalfa mosaic virus translational enhancer, up to 0.6% of the total protein in transgenic tobacco plants was cryIIIA as measured from immunoblot analysis. Bioassay data using potato beetle larvae confirmed this estimate.

Animals↗
PubMed1992

A high-performance liquid chromatography-based radiometric assay for acyl-CoA:alcohol transacylase from jojoba.

Acyl-CoA:alcohol transacylase catalyzes the final step in the biosynthesis of storage liquid wax esters from acyl-CoA fatty acids and fatty alcohols in a limited number of microbes, algae, and Simmondsia chinensis Link (jojoba). An improved and automated method of enzyme assay for this catalyst from cotyledons of jojoba is described. The assay method uses reversed-phase C18 high performance liquid chromatography (HPLC) to separate the labeled C30:1 liquid wax product, [14C]-dodecanyl-octadecenoate, from the unreacted substrate, [14C]octadecenoyl-CoA (oleyl-CoA), and other components produced from enzymes present in the crude homogenate of jojoba cotyledons, including [14C]-octadecenoic acid (oleic acid) and [14C]octadecenol (oleyol). Methods are also described for microscale chemical synthesis in one vessel of 14C-radiolabeled substrates and products for the transacylase. These labeled reagents are required to confirm the HPLC separations of reaction products. The radioactive components are quantitated using an on-line flow-through scintillation detector enabling sensitive and precise analysis of the reaction products.

Acyl Coenzyme A↗
PubMed1992

Effects of anti-transferrin receptor antibodies on the growth of neoplastic cells.

One approach to creating a state of iron deprivation in tumors is to expose them to monoclonal antibodies against the transferrin receptor (ATRAs). This paper reviews the recent history of studies with ATRAs. Both multivalent (IgM or IgA) and bivalent (IgG) ATRAs exhibit anti-tumor activity in vitro and in vivo, but IgG ATRAs appear to be most effective when used with an iron chelator such as deferoxamine or when used in pairs. Much more information is needed in order to understand: (1) how ATRAs work by themselves and in conjunction with chelators; (2) why ATRAs differ from one another in terms of their inhibitory potency; (3) whether ATRAs can be used successfully in conjunction with other anti-tumor agents, and (4) why tumors exhibit marked differences in their sensitivity to the effects of ATRAs. The toxicity of iron deprivation arising from ATRA treatment alone seems modest, but only further experimental work in vivo and in phase-1 clinical trials can determine whether the most recent observations can be converted into truly useful therapeutic tools.

Animals↗
PubMed1991

Resolution and characterization of pro-B and pre-pro-B cell stages in normal mouse bone marrow.

We have resolved B220+ IgM- B-lineage cells in mouse bone marrow into four fractions based on differential cell surface expression of determinants recognized by S7 (leukosialin, CD43), BP-1, and 30F1 (heat stable antigen). Functional differences among these fractions can be correlated with Ig gene rearrangement status. The largest fraction, lacking S7, consists of pre-B cells whereas the others, expressing S7, include B lineage cells before pre-B. These S7+ fractions, provisionally termed Fr. A, Fr. B, and Fr. C, can differentiate in a stromal layer culture system. Phenotypic alteration during such culture suggests an ordering of these stages from Fr. A to Fr. B to Fr. C and thence to S7- pre-B cells. Using polymerase chain reaction amplification with pairs of oligonucleotide primers for regions 5' of JH1, DFL16.1, and Jk1, we find that the Ig genes of Fr. A are in germline configuration, whereas Fr. B and C are pro-B cell stages with increasing D-J rearrangement, but no V-D-J. Finally, functional analysis demonstrates that the proliferative response to IL-7, an early B lineage growth factor, is restricted to S7+ stages and, furthermore, that an additional, cell contact-mediated signal is essential for survival of Fr. A.

Animals↗
PubMed1991

Role of iron in T cell activation: TH1 clones differ from TH2 clones in their sensitivity to inhibition of DNA synthesis caused by IgG Mabs against the transferrin receptor and the iron chelator deferoxamine.

TH1 and TH2 helper T cell clones have been studied with respect to their sensitivity to inhibition of DNA synthesis by an IgG anti-transferrin receptor antibody (ATRA), the iron chelator deferoxamine, and the combination of the two reagents. TH1 clones are very sensitive to ATRA-mediated inhibition of DNA synthesis while TH2 clones are very resistant, but both TH1 and TH2 clones show significant down-modulation of surface transferrin receptors after ATRA exposure. TH2 clones exhibit larger chelatable iron storage pools than TH1 clones, however, and even partial chelation of TH2 cell storage iron does not fully convert a TH2 clone to the ATRA sensitivity pattern of a TH1 clone. It is therefore proposed that the greater resistance of TH2 clones to ATRA mediated inhibition derives from the combined effects of larger and less labile iron storage pools. These studies provide novel evidence indicating that nonuniform iron metabolism can exist within the T cell compartment and thus raise questions as to why such differences exist and how they can be integrated into models of the T cell activation process. These studies also suggest that the cell-mediated immune response in vivo, which is known to be sensitive to iron deficiency, may be evoked by effector cells which resemble TH1 clones insofar as iron metabolism is concerned.

Animals↗
PubMed1991

Clonal immunoglobulin gene rearrangement in the infarcted lymph node syndrome.

The authors report a case of complete lymph node infarction in which a specific etiology could not be determined by morphologic or immunophenotypic studies; however, clonal rearrangement of the immunoglobulin gene was demonstrated by Southern blot hybridization of DNA extracted from the necrotic tissue. A subsequent lymph node biopsy later was diagnosed as malignant lymphoma, using morphologic, immunophenotypic and genotypic criteria. Identical clonally rearranged bands were present in DNA from both the infarcted nodal and the subsequent tissue biopsies. In the setting of lymph node necrosis, gene rearrangement studies may provide diagnostic information concerning clonality, even if morphologic and immunophenotypic studies are indeterminate for a lymphoproliferative process.

Aged↗
PubMed1990

Two mechanisms of transferrin receptor induction by anti-Ig in B cells.

By cross-linking surface Ig to the Fc gamma R, whole (IgG)-rabbit anti-Ig antibodies have been shown to substantially inhibit proliferation induced by LPS and F(ab')2 anti-Ig, and polyphosphoinositide hydrolysis induced by F(ab')2 anti-Ig. Surprisingly, however, whole anti-Ig was unable to inhibit induction of transferrin receptor (TfR) expression by LPS or F(ab')2 anti-Ig. Indeed, whole anti-Ig on its own induced TfR as early as 4 h. TfR induction by F(ab')2 anti-Ig and by LPS was accompanied by an early increase in TfR mRNA, and was prevented by inhibitors of protein and RNA synthesis and therefore can be ascribed to a transcriptional mechanism. In contrast, whole anti-Ig induced TfR even in the presence of protein and RNA synthesis inhibitors. Little or no TfR mRNA was detectable after 4 or 16 h of exposure to whole anti-Ig, whereas increased TfR mRNA was evident after 4 h of F(ab')2 anti-Ig or LPS. Antibody to the Fc gamma R (2.4G2) restores the ability of whole anti-Ig to generate increased TfR expression via the transcriptional route. We conclude that whole anti-Ig induces TfR mostly by using preexisting TfR molecules through a mechanism different from the transcriptional mechanism triggered by F(ab')2 anti-Ig and LPS.

Animals↗
PubMed1990

Synergistic inhibition of lymphoid tumor growth in vitro by combined treatment with the iron chelator deferoxamine and an immunoglobulin G monoclonal antibody against the transferrin receptor.

Data are presented indicating that the growth of 5 out of 5 murine lymphoid tumors can be inhibited in a synergistic fashion in vitro by combined treatment with the iron chelator deferoxamine (DFO) and an immunoglobulin G (IgG) monoclonal anti-transferrin receptor antibody (ATRA). A two-way dose/response analysis shows that the ATRA becomes more efficient as an inhibitor with increasing doses of DFO. Flow cytometric studies further support the view that IgG ATRAS impair transferrin receptor (TR) function by causing TR down-modulation and degradation, even when the presence of DFO acts to promote increased cell surface TR expression. It is also shown that an IgG ATRA is nearly as effective as an IgM ATRA in inhibiting tumor cell growth when used in combination with DFO. Finally, studies with the iron chelator picolinic acid show that it produces only additive, or very slightly supra-additive, effects when used in combination with the ATRA. Therefore, these studies not only continue to suggest that combination chelator/ATRA therapy warrants further investigation as a tool in the therapy of hematopoietic malignancies, but also make the following new points: (1) the clinically familiar iron chelator deferoxamine, but not all iron chelators, produces synergistic inhibition of tumor growth in vitro with ATRAS; and (2) IgG ATRAS, which may be clinically more attractive reagents than IgA or IgM ATRAS because of better access to extra vascular tissue spaces, have unexpectedly been found to function as powerful growth inhibitors when used in combination with DFO.

Animals↗
PubMed1990

CD4+ murine T cell clones that express high levels of immunoglobulin binding belong to the interleukin 4-producing T helper cell type 2 subset.

A panel of 20 murine CD4+ clones was examined for the presence of surface membrane receptors for IgA, IgM, IgD, IgE, and IgG. High level expression of multiple Fc receptors (FcRs) was found on all Th2 clones. FcR expression was low or undetected on the Th1 clones. The preferential expression of FcR on activated Th2 cells suggests potential mechanisms for immunoregulatory interactions with B cells.

Animals↗
PubMed1990

A patient with simultaneous absence of "classical" natural killer cells (CD3-, CD16+, and NKH1+) and expansion of CD3+, CD4-, CD8-, NKH1+ subset.

The clinical manifestations of putative natural killer (NK) cell deficiency are not well-known but theoretically should include recurrent tumors and systemic viral infections. In this article, we discuss a patient with recurrent condylomata, vulvar and cervical carcinoma in situ, pulmonary infiltrates of unknown significance, and a hypercoagulable state. This patient has a dramatic persistent deficiency in her circulating "classic" NK cells (CD3-, CD16+, NKH1+) and a simultaneous persistent expansion of a normally minor lymphocyte cell subset (CD3+, CD4-, CD8-, NKH1+) that does not express the alpha beta heterodimer of the T cell receptor. T-lymphocyte function, as measured by mitogen and alloantigen responsiveness in vitro, was normal. The coexistence of this particular clinical complex with this unusual set of laboratory abnormalities tends to emphasize our meager understanding of the biologic role of NK cells. At the very least, these findings suggest that the clinical manifestations of NK cell deficiency need not be dominated by disseminated systemic viral infections and that perhaps there should be a higher index of suspicion for the scrutinization of NK cell function.

Adult↗
PubMed1990

Kappa immunoglobulin light chain gene rearrangement in a T-lineage chronic lymphocytic leukemia.

Until recently, only B-lineage lymphoid cells were observed to rearrange kappa immunoglobulin light chain genes. The authors examine peripheral blood mononuclear cells from a patient with chronic lymphocytic leukemia. More than 90% of these cells bound T-lymphocyte specific antibodies, failed to bind B-lymphocyte specific antibodies, had rearranged T-cell receptor beta-chain genes and had retained immunoglobulin heavy chain genes in the germline configuration. Despite these T-lineage markers, the majority of these cells had rearranged kappa immunoglobulin light chain genes. This provides the first conclusive evidence for rearranged kappa genes in malignant T-lineage cells and warns that gene rearrangement studies alone cannot indicate tumor cell lineage. To detect T-lineage cells that rearrange immunoglobulin genes, multiple immunophenotypic and genotypic parameters must be evaluated. These cells may provide important models to study how normal and malignant cells rearrange lymphocyte receptor genes.

Adult↗
PubMed1990

Clonal immunoglobulin gene rearrangement in nodular lymphoid hyperplasia of the gastrointestinal tract associated with common variable immunodeficiency.

The authors report a case of common variable immunodeficiency associated with nodular lymphoid hyperplasia of the gastrointestinal tract in which a clonal population of lymphoid cells was detected by immunophenotypic and genotypic studies on tissue obtained by colonoscopic biopsy. The patient has been followed up for more than 50 months without clinical, radiographic, or pathologic evidence of lymphoma. The significance of clonal rearrangement in the setting of immunodeficiency and the role of genotypic studies in defining lymphoid malignancy are discussed.

Adolescent↗
PubMed1990

The diagnostic utility of immunophenotyping and immunogenotyping in the pathologic evaluation of lymphoid proliferations.

One hundred eighty-two specimens of suspected lymphoma and lymphocytic leukemia were examined by morphology, immunophenotype, and immunogenotype (genotype) in order to answer the following questions: How often and in what situations does immunophenotyping help resolve a diagnostic problem that is not resolved by morphology? How frequently does genotyping help resolve a diagnostic problem that is not resolved by morphology and immunophenotyping? Of 182 cases for which fresh tissue was available, sixty-five cases were considered morphological diagnostic problems: There were 32 cases of neoplasia versus non-neoplastic proliferation, 16 cases of neoplasia with undifferentiated or ambiguous morphology, and 17 cases of lymphoma or lymphocytic leukemia with an uncertain subtype. Immunophenotyping helped to resolve 33 of these 65 cases. Of the remaining 32 cases genotyping helped to resolve the diagnosis in 16. These results suggest that immunophenotyping may diagnose approximately 50% of those cases which present a morphological problem, and that genotyping is also helpful in a limited but significant number of problem cases.

Diagnosis, Differential↗
PubMed1990

Immunophenotypic and genotypic characterization of primary non-Hodgkin's lymphoma of the gastrointestinal tract.

Antigen receptor gene rearrangement studies have been applied to gastrointestinal (GI) lymphoid proliferations in only a limited number of cases, and their use and contribution to the diagnosis and characterization of GI lymphomas is unknown. We retrospectively studied 17 cases of primary GI lymphoma using fresh/frozen tissue with a combination of immunophenotypic and genotypic techniques. The vast majority of the neoplasms were B-cell lymphomas (88%) with rare T-cell tumors. The most common B-cell immunophenotype was IgM-kappa (40%), while five of the B-cell lymphomas (33%) lacked surface light chain immunoglobulin. Immunophenotypic evidence of histiocytic differentiation was not identified. Clonality was confirmed in 59% (10/17) of the neoplasms by immunophenotyping and 88% (15/17) by antigen receptor gene rearrangement studies. All of the 15 B-cell lymphomas (100%) demonstrated clonally rearranged immunoglobulin gene rearrangement. The two lymphomas with T-cell immunophenotypes did not demonstrate T-cell receptor beta-chain gene rearrangement. Antigen receptor gene rearrangement data can be useful and may even be necessary in certain cases for the proper classification and/or diagnosis of GI lymphoid proliferations.

Adult↗
PubMed1989

Transferrin receptor synthesis is an early event in B cell activation.

Purified, small resting mouse B cells appear to express low levels of transferrin receptor (TfR) as detected by flow cytometry. Moreover, when such cells are stimulated with LPS or F(ab')2 anti-mu, they show increased expression of TfR as early as 4 h after activation when the cells are at the boundary of G0 and G1 phase by cell cycle analysis. Cells treated with anti-mu increased TfR expression gradually, reaching a plateau after 46 h, whereas cells with LPS reached their plateau by 12 h. The kinetics of induction of increased TfR expression was similar for both small and large B cells. Inhibition of protein synthesis with anisomycin or inhibition of transcription with actinomycin-D blocked the increased expression of TfR at 4 h. Northern blot analysis showed a marked increase of TfR mRNA at 2 and 4 h with either anti-mu or LPS which was then followed by an apparent decline at 16 h. These findings together with other recent studies justify reevaluation of the generally accepted models placing TfR induction late in the G1 phase of the lymphocyte activation sequence. They support the concept that in the B lymphocyte the TfR gene is selectively transcribed earlier than previously thought, before the general increase in RNA synthesis.

Animals↗
PubMed1989

Analysis of lymphoid population in scid mice; detection of a potential B lymphocyte progenitor population present at normal levels in scid mice by three color flow cytometry with B220 and S7.

We have used 3 color FACS analysis (together with dead cell exclusion by propidium iodide) to ascertain the levels of lymphoid lineage cells present in typical young adult (2-5 month) SCID mice. Both mature and early B and T lineage cells are severely decreased (greater than 100X) in thymus, spleen and peritoneum of such mice. Analysis revealed a significant fraction of B220+ cells in bone marrow and, curiously, all such cells co-expressed a determinant recognized by the S7 antibody, likely lost early in B lineage differentiation. Thus, together with B220, expression of S7 may serve to mark the stage at which the SCID defect first becomes manifest, at least in the B lineage. This suggests that B220+/S7+ cells in bone marrow may be pro-B cells or even a lymphoid progenitor population.

Animals↗