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Biomedical subjects

H M Lederman

Publications and source records attributed to H M Lederman.

At least 91 records · Page 5Linked to original sources
PubMed1985

Benefit of intravenous IgG replacement in hypogammaglobulinemic patients with chronic sinopulmonary disease.

Seven patients with hypogammaglobulinemia and chronic sinopulmonary infections were treated with a preparation of intravenous gammaglobulin. In order to maintain levels of serum IgG at greater than 500 to 750 mg/dl four weeks after infusion, 0.6 g/kg was administered every month. Stable serum levels were achieved after three to eight months. After six to 12 months of this regimen, there was significant reduction in acute infections requiring hospitalization, amelioration of clinical and radiographic evidence of chronic maxillary sinusitis, and improvement in pulmonary symptoms and pulmonary function test results. The administration of increased amounts of IgG intravenously is of benefit in patients with chronic sinopulmonary infections.

Adolescent↗
PubMed1985

X-linked agammaglobulinemia: an analysis of 96 patients.

We have defined the clinical presentation and course of X-linked agammaglobulinemia (X-LA) by means of a multi-center retrospective survey of 96 patients. Infections were the most common presenting feature of patients with X-LA. The most frequent infections involved the upper respiratory tract (75%), lower respiratory tract (65%), gastrointestinal tract (35%), skin (28%), and central nervous system (16%). Clinical clues to the diagnosis of X-LA were the chronic or recurrent nature of infections, a family history of immunodeficiency, and infections at more than one anatomic location. Infections remained a significant problem after the diagnosis of X-LA was made and gamma-globulin prophylaxis had been instituted. One or more chronic infectious diseases occurred in 71% of patients. The respiratory tract was the most common site of disease, and the gastrointestinal tract was relatively spared. Patients died at a mean age of 17 years. The two major causes of death were chronic pulmonary disease with resultant cardiac failure, and disseminated viral infections which characteristically caused a dermatomyositis-like syndrome, hepatitis, pneumonitis, and meningoencephalitis.

Agammaglobulinemia↗
PubMed1985

The origin of T cell colonies from T depleted human lymphocyte populations: analysis by limiting dilution.

We have examined the identity of the T colony progenitor cell (TCPC) in T cell depleted peripheral blood mononuclear cells (PBM-E-). PBM were cultured in a limiting dilution assay utilizing PHA, T cell growth factor (TCGF) and irradiated feeder cells in semi-solid medium. The TCPC frequency was 0.10 in PBM-E+ and 0.0006 in PBM-E-. The observed TCPC frequency in PBM-E- was directly proportional to the number of contaminating PBM-E+; all of the T colonies which arose from PBM-E- could be accounted for by contaminating T cells. In other experiments, E+ cells were generated from PBM-E-, incubated in the presence of PHA and TCGF. This appearance of E+ cells could be totally abrogated by incubation with hydroxyurea. Similarly, the TCPC frequency in PBM-E- was increased by pre-incubation with PHA and TCGF, and this increase was blocked by hydroxyurea. These experiments suggest that a small number of contaminating T cells can rapidly expand in culture and that these residual T cells, not a population of pre-T cells, are the source of TCPC within the PBM-E- population.

Adult↗
PubMed1984

The intracellular pH of quiescent and proliferating human and rat thymic lymphocytes.

We compared the cytoplasmic pH (pHi) of quiescent and actively cycling thymic lymphocytes. Human and rat thymocyte suspensions were fractionated by centrifugation on one-step albumin density gradients. The pellet was composed of small, quiescent cells and the interphase contained mostly larger, actively cycling cells with a high proliferation index. When measured using [14C]-dimethyloxazolidinedione (DMO), pHi in the large cells of both species was approximately 0.15 units more alkaline than in the small cells. However, these differences were not detectable when pHi was measured with carboxylated fluorescein derivatives generated in situ by cytoplasmic enzymes. This apparent discrepancy can be explained by compartmentation of DMO, which accumulates in the alkaline mitochondrial matrix. Comparison of the mitochondrial content of quiescent and cycling thymocytes by several methods showed that the latter contained over 2.5-fold more mitochondria per unit cell volume. Assuming a constant intramitochondrial pH, this difference can account for the observed accumulation of DMO (i.e., apparent cytoplasmic alkalinity) in the actively proliferating cells. Therefore, no evidence was found for the existence of differences in pHi between quiescent and proliferating lymphocytes. Moreover, caution must be exercised when comparing DMO partition data in cells with varying relative mitochondrial content.

Animals↗
PubMed1984

Monocytes are required to trigger Ca2+ uptake in the proliferative response of human t lymphocytes to staphylococcus aureus protein A.

We have used the T-cell mitogen Staphylococcus aureus protein A (SpA) to study the role of monocytes in the early events of T-lymphocyte activation. The mitogenic response of human peripheral blood mononuclear cells (PBM) was compared to the response of populations enriched for T cells by E-rosetting (PBM-E+). In response to SpA, the [3H]thymidine uptake of PBM-E+ was reduced by 80% compared to PBM. The reduced response of PBM-E+ was completely restored by the addition of irradiated PBM-E- or the monocyte-like human cell line U-937 but not by addition of irradiated PBM-E+. A direct interaction of SpA with monocytes is important since proliferative responses could be generated by preincubation of U-937 with SpA followed by washing and subsequent addition to PBM-E+; incubation of PBM-E+ with SpA followed by washing and subsequent addition of U-937 did not result in a proliferative response. To further delineate the role of the monocyte, we examined the ability of soluble SpA, U-937, or U-937 preincubated with SpA to trigger Ca2+ flux into T lymphocytes, an early step in initiation of the proliferative response. SpA-pretreated U-937, but neither SpA nor monocytes alone, triggered Ca2+ movement into the T lymphocytes. This defines a new role for the monocyte in the early events of T-lymphocyte activation.

Calcium↗
PubMed1984

Purine metabolism in human T lymphocytes: role of the purine nucleoside cycle.

Human intrathymic T lymphocytes were separated by a bovine serum albumin density gradient into a population of G1-phase small thymocytes and a population of S-phase-enriched large thymocytes. Purine metabolism was studied in these thymocyte populations, representing immature T lymphocytes, and compared with the metabolism of mature T lymphocytes isolated from the peripheral blood. De novo purine biosynthesis was highly cell cycle dependent; i.e., de novo purine biosynthetic activity was found only in large S-phase thymocytes, whereas both G1 T-cell populations lacked any significant activity. Thus G1-phase small thymocytes and G1-phase peripheral blood T lymphocytes have only salvage pathways to maintain their purine nucleotide pools. Despite the similarity of purine salvage activities in G1 thymocytes and in peripheral blood T lymphocytes, small thymocytes have fourfold lower levels of purine nucleoside triphosphates. The decreased levels of purine nucleotides in G1 thymocytes may be the result of increased purine efflux. It was found that an unusually large proportion (24-48%) of hypoxanthine incorporated by G1 thymocytes is excreted into the medium in the form of inosine.

Cell Separation↗
PubMed1984

Deferoxamine: a reversible S-phase inhibitor of human lymphocyte proliferation.

Deferoxamine is widely used therapeutically as a chelator of ferric ion in disorders of iron overload. This study demonstrates that this drug is a potent inhibitor of DNA synthesis by human B and T lymphocytes in vitro, but has relatively little effect on the synthesis of RNA and protein. The inhibitory effects of deferoxamine are completely reversible by washing or by adding stoichiometric amounts of Fe3+. Micromolar concentrations of deferoxamine decrease intracellular levels of deoxyribonucleoside triphosphates, which is similar to the effects of hydroxyurea. The binding of iron by deferoxamine likely causes an inhibition of ribonucleotide reductase activity, thereby preventing cells from completing the S phase of the cell proliferation cycle. As a reversible and nontoxic S-phase inhibitor, it may have important experimental and therapeutic applications.

Adolescent↗
PubMed1984

Functional characterization of human thymocyte subpopulations separated by density gradient centrifugation.

A bovine serum albumin gradient was used to separate two populations of human thymocytes--a minority population (8%) of large thymocytes (LT) and a majority population (92%) of small thymocytes (ST). Fifty per cent of LT cells were in the S, G2 or M phases of the cell cycle compared to 5% of ST cells and 15% of unfractionated thymocytes. LT cells proliferated in response to T cell mitogens and included all of the T colony precursor cells (TCPC). In contrast, ST cells proliferated with mitogens only in the presence of added T cell growth factors and contained none of the thymocyte TCPC. ST cells neither helped nor suppressed the function of LT cells in any assay. This separation technique has provided a rapid method for isolating functionally distinct thymic lymphocyte subpopulations and permitted a further definition of the TCPC in the human thymus. Furthermore it should prove useful in studies of thymocytes at different stages of the cell cycle.

Adolescent↗
PubMed1983

Purine and pyrimidine metabolism in human T lymphocytes. Regulation of deoxyribonucleotide metabolism.

Purine and pyrimidine deoxyribonucleoside metabolism was studied in G1 and S phase human thymocytes and compared with that of the more mature T lymphocytes from peripheral blood. Both thymocyte populations have much higher intracellular deoxyribonucleoside triphosphate (dNTP) pools than peripheral blood T lymphocytes. The smallest dNTP pool in S phase thymocytes is dCTP (5.7 pmol/10(6) cells) and the largest is dTTP (48 pmol/10(6) cells), whereas in G1 thymocytes, dATP and dGTP comprise the smallest pools. While both G1 and S phase thymocytes have active deoxyribonucleoside salvage pathways, only S phase thymocytes have significant ribonucleotide reduction activity. We have studied ribonucleotide reduction and deoxyribonucleoside salvage in S phase thymocytes in the presence of extracellular deoxyribonucleosides. Based on these studies, we propose a model for the interaction of deoxyribonucleoside salvage and ribonucleotide reduction in S phase thymocytes. According to this model, extracellular deoxycytidine at micromolar concentrations is efficiently salvaged by deoxycytidine kinase. However, due to feedback inhibition of deoxycytidine kinase by dCTP, the maximal level of dCTP which can be achieved is limited. The salvage of both deoxyadenosine and deoxyguanosine (up to 10(-4) M) is completely inhibited in the presence of micromolar concentrations of deoxycytidine, whereas the salvage of thymidine is unregulated resulting in large increases in dTTP levels. Moreover, significant amounts of the salvaged deoxycytidine is used for dTTP synthesis resulting in further increase of dTTP pools. The accumulated dTTP inhibits the reduction of UDP and CDP while stimulating GDP reduction and subsequently also ADP reduction. The end result of the proposed model is that S phase thymocytes in the presence of a wide range of extracellular deoxyribonucleoside concentrations synthesize their pyrimidine dNTP by the salvage pathway, whereas purine dNTPs are synthesized primarily by ribonucleotide reduction. Using the proposed model, it is possible to predict the relative intracellular dNTP pools found in fresh S phase thymocytes.

Cell Cycle↗
PubMed1983

Growth and characterization of T cell colonies from human thymus.

A semisolid microculture system was used to study T cell colonies grown from human thymocytes. Colony growth was absolutely dependent upon media conditioned by peripheral blood leukocytes (PBL) in the presence of phytohemagglutinin. Plating efficiency was further enhanced by the addition of a non-T, adherent, radiation-resistant (7500 rad) PBL subpopulation, but was not enhanced by culture supernatants of these cells. The T colony precursor cell in the thymus occurred with a frequency of 8.0 X 10(-3) and had a surface receptor for the OKT3 monoclonal antibody. Thymocyte colony cells were functionally distinct from PBL and the major thymocyte population. The colony cells proliferated in response to T cell mitogens, but only in the presence of exogenous growth factors. The cells stimulated normal PBL in mixed leukocyte culture (MLC), but did not respond to alloantigens in MLC or in assays of spontaneous cytotoxicity. This culture system should prove helpful in the study of human thymocyte differentiation.

Adolescent↗
PubMed1981

In vitro synthesis of IgG by peripheral blood lymphocytes in chronic liver disease.

In vitro IgG synthesis by peripheral blood mononuclear cells (PBM) from patients with chronic liver disease (CLD) was studied. In addition, the effect of pokeweed mitogen (PWM), polyadenylic-polyuridylic acid complexes (poly A:U) and thymosin fraction 5 on IgG synthesis was determined. Unstimulated cultures of PBM from patients with chronic active hepatitis (CAH) and alcoholic cirrhosis (AC) synthesized significantly higher quantities of IgG than the controls. Moreover, there was a direct correlation between serum IgG concentrations and the quantity of newly synthesized IgG in these unstimulated cultures. PWM, poly A:U and thymosin each stimulated increased IgG synthesis in the controls. While neither poly A:U nor thymosin enhanced IgG synthesis in patients with CLD, PWM increased IgG synthesis in CAH but not AC. These results indicate that spontaneous in vitro B cell synthesis of IgG is enhanced in CLD and may reflect antigenic stimulation in vivo.

Adult↗
PubMed1977

Ankylosing spondylitis with selective IgA deficiency and a circulating anticoagulant.

A patient with ankylosing spondylitis was found to have selective IgA deficiency and a non-heparin, immediate-acting antithrombin (antithrombin V). T cells were decreased, and serum IgG was increased. In vitro synthesis of IgG by peripheral blood lymphocytes was very high. This association of ankylosing spondylitis with the T cell and protein abnormalities is probably fortuitous but does demonstrate that severe spondylitis may evolve in the absence of IgA.

Antithrombins↗
PubMedDate not supplied

Lymphoid malignancy as a presenting sign of ataxia-telangiectasia.

Ataxia-telangiectasia (AT) is an uncommon genetic disorder characterized by cerebellar ataxia, oculocutaneous telangiectasias, progressive immunodeficiency, and a predisposition to lymphoid malignancy. The genetic defect in AT predisposes not only to malignancy but also to severe toxicity from anti-neoplastic therapies. It is important to consider the diagnosis of AT in any child with a lymphoid malignancy at a younger than expected age, or who has a pre-existing ataxia, to anticipate unusually severe toxicities from the antineoplastic therapy, to avoid confusing the development of ataxia with toxicity from therapy, and to provide appropriate genetic counseling. We describe two children at a young age with a lymphoid malignancy diagnosed before the diagnosis of AT. One patient had severe toxicity from his chemotherapy, requiring truncation of the planned course of treatment. The other child was able to tolerate his entire planned course of therapy, but ataxia that was initially interpreted as toxicity from chemotherapy rather than as a sign of his AT developed. Lymphoid malignancy may be the presenting sign of AT. Making this diagnosis may influence therapy of the malignancy. The neurologic manifestations of the disease can be misinterpreted as toxicities of the chemotherapy, and diagnosis of AT allows appropriate genetic counseling for the family.

Ataxia Telangiectasia↗