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Biomedical subjects

E H Field

Publications and source records attributed to E H Field.

36 records · Page 2Linked to original sources
PubMed1992

Altered IFN-gamma and IL-4 pattern lymphokine secretion in mice partially depleted of CD4 T cells by anti-CD4 monoclonal antibody.

Complete elimination of CD4 cells by in vivo treatment with anti-CD4 mAb may result in B cell polyclonal activation. Additionally, mice treated with doses of anti-CD4 that eliminate half the CD4 cells produced higher anti-SRBC antibody responses than controls. This suggests that partial CD4 depletion enhances Th2-like function. To test this hypothesis we examined Th1 and Th2 lymphokine potential in mice partially depleted of CD4 cells. We measured IL-4 and IFN-gamma secretion by stimulated unfractionated spleen cells and analyzed activated, purified CD4 cells by RNA in situ hybridization to determine the percentage of IFN-gamma- or IL-4-producing cells. Unfractionated splenocytes from partially CD4-depleted mice secreted more IL-4 and less IFN-gamma than splenocytes from control mice. In situ hybridization proved that CD4 cells from partially depleted mice contained a higher percentage of IL-4 and a lower percentage of IFN-gamma-producing cells than controls. These results indicate that treatment with a dose of mAb resulting in partial CD4 depletion may permit increased Th2-like lymphokine expression. This study also provides evidence that cells committed to Th2-like function exist in vivo in mice.

Animals↗
PubMed1992

Kinetics of anti-CD4-induced T helper cell depletion and inhibition of function. Activation of T cells by the CD3 pathway inhibits anti-CD4-mediated T cell elimination and down-regulation of cell surface CD4.

In vivo treatment with anti-CD4 antibody profoundly suppresses a number of T cell-dependent responses and is clinically useful in the treatment of certain mouse models of autoimmune disease. Treatment with anti-CD4 antibody will inactivate and can deplete CD4 T cells, but the mechanisms responsible for these effects are incompletely understood. When mouse spleen cells were exposed in vitro to both SRBC and monoclonal anti-CD4, there was 55% reduction of the anti-SRBC response. If cultures were preincubated with anti-CD4 for 48 h before in vitro challenge, the reduction was greater than 80%. When unfractionated spleen cells were cultured with anti-CD4 for 96 h, there was actual elimination of CD4 cells in these cultures since virtually all CD3+ cells were CD8+. Activation of T cells by exposure to anti-CD3 rendered them resistant to antibody-mediated CD4 depletion. This resistance to CD4 depletion was seen even in cultures that were pretreated with anti-CD4 for as long as 24 h before anti-CD3 exposure. In cultures of purified T cells, anti-CD4 did not eliminate CD4 T cells. However, culture of T cells with macrophage-rich adherent cells and anti-CD4 resulted in elimination of CD4 T cells. Thus, it appears that macrophages play a role in anti-CD4-induced T cell elimination. While anti-CD4 did not eliminate CD4 cells from a population of purified T cells, there was profound down-regulation of cell surface CD4. Activating T cells with immobilized anti-CD3 before addition of anti-CD4 prevented down-regulation of CD4. These experiments demonstrate that T cell activation by anti-CD3 renders the activated cells resistant to antibody-induced CD4 down-regulation and to antibody-induced CD4 T cell depletion. These findings may have relevance to the application of anti-CD4 therapy in human diseases that are mediated by activated Th cells.

Antigen-Antibody Reactions↗
PubMed1992

Blocking of mixed lymphocyte reaction by spleen cells from total lymphoid-irradiated mice involves interruption of the IL-2 pathway.

Treatment with total lymphoid irradiation (TLI) before organ transplantation results in high incidences of donor-specific tolerance. However, the exact mechanism of how TLI induces or maintains tolerance is not known. In many experimental systems of tolerance, lack of IL-2 plays a central role in tolerance induction, as stimulation of immunocompetent cells with Ag in an insufficient IL-2 environment results in tolerance. To examine whether tolerance induction by TLI might involve the IL-2 pathway, we examined how TLI cells affect the ability of immunocompetent cells to produce IL-2 and express IL-2R in the MLR. Responder cells from MLR cultures in which cells from TLI-treated mice were added proliferated 50 to 70% less and produced 68 to 94% less IL-2 bioactivity than responder cells from control cultures. However, coculture of TLI cells into MLR did not alter IL-2R expression on responder cells, as measured by two-color FACS analysis. We found no evidence that TLI cells deleted MLR responder cells. Interestingly, exogenous IL-2 did not restore proliferation of MLR responder cells. These results suggest that TLI may induce tolerance by interrupting the IL-2 pathway in immunocompetent cells. Moreover, that exogenous IL-2 failed to restore immunocompetence suggests that tolerance in the TLI model may be easy to induce and very stable, and provides a rationale for the higher incidences of donor-specific tolerance after TLI treatment.

Animals↗
PubMed1990

Mechanisms of total lymphoid irradiation-induced immunosuppression. II. Failure of con A-stimulated splenocytes from TLI-treated mice to express IL-2 and IL-2 receptor RNA.

Total lymphoid irradiation is a radiotherapy procedure used as an alternative immunosuppressive regimen in organ transplantation. Following TLI mature lymphocytes are depleted, and splenocytes do not proliferate to mitogens, produce IL-2, or express IL-2 receptors. We now show that mitogen stimulated splenocytes from TLI-treated mice do not secrete IL-2 protein by an IL-2 ELISA assay. Northern blot analysis and RNase protection assays reveal that TLI splenocytes do not make IL-2 RNA or IL-2 receptor RNA following mitogen stimulation. TLI splenocytes produce at least 1000 times less IL-2 RNA after Con A stimulation than normal splenocytes. TLI therapy resembles anti-CD4 therapy and CsA in that each results in an IL-2-"depleted" state.

Animals↗
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

The immunosuppressive mechanism of total lymphoid irradiation. I. The effect on IL-2 production and IL-2 receptor expression.

Total lymphoid irradiation is an effective immunosuppressive therapy used to prepare patients for organ transplantation and to treat several autoimmune diseases. We have used the mouse model to investigate the mechanism of TLI-induced immunosuppression. Mice were irradiated with 250-rad daily fractions to a total dose of 3500 rads. Splenocytes from control and TLI-treated mice were analyzed for IL-2 production, IL-2 receptor expression after mitogen stimulation, and percent L3T4 positive cells. At two weeks following the completion of TLI, IL-2 production from whole spleen populations had decreased 90% compared with controls (TLI mean IL-2 units = 25 +/- 9.0, control mean = 277 +/- 104). IL-2 receptor expression on splenocytes following Con A stimulation was decreased 80% compared with controls (TLI mean percentage of IL-2 receptor expressing cells = 16.2 +/- 4.1, control mean = 82.0 +/- 7.5). L3T4+ cells that expressed IL-2 receptor were also decreased following TLI (TLI mean = 4.4 +/- 1.4, control mean = 22.0 +/- 3.8), as were proliferative responses to Con A and PHA. Addition of recombinant mouse IL-2 did not restore IL-2 receptor expression or proliferative responses. Whole TLI-treated splenocytes did not suppress IL-2 production or proliferative responses of normal splenocytes. These immunologic abnormalities recovered over time, and by 8 weeks post TLI IL-2 production, IL-2 receptor expression, L3T4+ cell numbers and proliferative responses had returned toward normal. These results suggest that TLI therapy transiently depletes IL-2 producing, IL-2 receptor expressing, and mitogen responsive lymphocytes. The immunosuppression is not mediated through a suppressor cell and is independent of IL-2 production.

Animals↗
PubMed1988

Treatment of lupus nephritis with total lymphoid irradiation. Observations during a 12-79-month followup.

Seventeen patients with intractable lupus nephritis and nephrotic syndrome were treated with total lymphoid irradiation. Statistically significant improvement in mean renal disease and serologic activity parameters occurred within 3 months and persisted for at least 3 years. Although there was a marked reduction of T helper cell numbers and function after total lymphoid irradiation, recovery of these parameters was not associated with a return of disease activity. Risks of sterility, severe infections, and hematologic malignancy appeared to be lower than with alkylating agents.

Adolescent↗
PubMed1988

Transient rheumatoid factor positivity in acute human parvovirus B19 infection.

The relationship between parvovirus B19 infection and classic rheumatoid arthritis remains to be determined. We describe two adult patients with serologically documented acute parvovirus B19 infection who presented with sudden onset of symmetric polyarthritis, skin eruption, and rheumatoid factor positivity. Rheumatoid factor positivity and symptoms resolved within five months. We conclude that a diagnosis of B19 arthropathy should be considered in any patient with recent acute or subacute onset of symmetric polyarthralgia or polyarthritis and rheumatoid factor positivity, which would otherwise suggest a diagnosis of early rheumatoid arthritis.

Arthritis↗
PubMed1987

The gene encoding the mouse T cell differentiation antigen L3T4 is located on chromosome 6.

We have used Southern blot analysis of DNA from somatic cell hybrids to map the chromosomal location of the mouse L3T4 T cell differentiation antigen gene to chromosome 6. This finding is of interest because both L3T4 and the alternative T cell differentiation antigen Lyt-2 are homologous to kappa-immunoglobulin light chain-variable regions, and the genes encoding kappa and Lyt-2 are also located on mouse chromosome 6.

Animals↗
PubMed1987

Long-term followup of rheumatoid arthritis patients treated with total lymphoid irradiation.

Total lymphoid irradiation was administered to 32 patients with intractable rheumatoid arthritis. Twenty-four patients showed at least a 25% improvement in 3 of 4 disease activity parameters, which persisted during the followup period of up to 48 months. Eight of the 32 patients required adjunctive immunosuppressive drug therapy to maintain improvement. Four patients died after total lymphoid irradiation; the causes of death were acute myocardial infarction (1 patient), pulmonary embolism (1 patient), and rheumatoid lung disease complicated by respiratory infection (2 patients). After therapy, patients exhibited a prolonged reduction in the number and function of circulating T helper cells.

Aged↗
PubMed1986

Isolation and sequence of L3T4 complementary DNA clones: expression in T cells and brain.

T lymphocytes express on their surface not only a specific receptor for antigen and major histocompatibility complex proteins, but also a number of additional glycoproteins that are thought to play accessory roles in the processes of recognition and signal transduction. L3T4 is one such T-cell surface protein that is expressed on most mouse thymocytes and on mature mouse T cells that recognize class II (Ia) major histocompatibility complex proteins. Such cells are predominantly of the helper/inducer phenotype. In this study, complementary DNA clones encoding L3T4 were isolated and sequenced. The predicted protein sequence shows that L3T4 is a member of the immunoglobulin gene superfamily. It is encoded by a single gene that does not require rearrangement prior to expression. Although the protein has not previously been demonstrated on nonhematopoietic cells, two messenger RNA species specific for L3T4 are found in brain. The minor species comigrates with the L3T4 transcript in T cells, whereas the major species is 1 kilobase smaller.

Amino Acid Sequence↗
PubMed1984

Glomerular capillary wall function in human lupus nephritis.

Eighteen patients with nephrotic-range proteinuria due to lupus nephritis were evaluated with a differential solute clearance technique. Renal plasma flow was similar to that in 17 healthy volunteer controls (506 +/- 75 vs. 503 +/- 32 ml/min, P = NS), while oncotic pressure in pre- and postglomerular plasma was depressed by 9.2 and 17.3 mmHg, respectively. These findings are consistent with elevation of net ultrafiltration pressure and suggest that glomerular hypofiltration (51 +/- 9 vs. 103 +/- 8 ml/min, P less than 0.001) was due to a lowered glomerular ultrafiltration coefficient (Kf). In lupus nephritis the fractional clearance of smaller dextrans (radii less than 50 A) was depressed, while that of larger dextrans (radii greater than 50 A) was elevated. A pore model of solute transport, when applied to the dextran filtration data, revealed a subpopulation of large protein-permeable pores in lupus nephritis not present in controls. Moreover, the fraction of glomerular filtrate permeating these enlarged pores correlated directly with the respective fractional clearances of albumin (r = 0.71) and immunoglobulin G (r = 0.75) in individual patients. Immunosuppression in nine patients was associated with an increase of the filtration rate and filtration fraction. Conversely, fractional protein clearances and the area fraction of the glomerular membrane occupied by large pores decreased. We conclude that human immune glomerular inflammation is manifested by a reduction of Kf and increased glomerular porosity and that these membrane alterations are partially reversible.

Adult↗
PubMed1984

Reduced in vitro immune responses of purified human Leu-3 (helper/induced phenotype) cells after total lymphoid irradiation.

Patients treated with total lymphoid irradiation (TLI) for intractable rheumatoid arthritis showed marked decreases in the in vitro proliferative responses of peripheral blood mononuclear cells (PBM) to antigens and mitogens. To determine whether an intrinsic deficit in helper/inducer cell proliferation contributed to decreased responses, cells of the helper/inducer phenotype were purified from the PBM of treated patients by using monoclonal anti-Leu-3 antibody and a modified panning procedure. The purified Leu-3 cells obtained after TLI showed a marked reduction in [3H]thymidine incorporation in response to allogeneic lymphocytes, PHA, Con A, and several protein antigens, as compared with that of cells from the same patients obtained before TLI. In addition, the quantity of Leu-3 surface antigen on the panned cells was reduced after TLI. The results suggest that TLI induces prolonged qualitative as well as quantitative changes in circulating Leu-3 T cells. These changes may contribute to the clinical effects of TLI.

Antigens, Surface↗
PubMed1983

Sustained improvement of intractable rheumatoid arthritis after total lymphoid irradiation.

Total lymphoid irradiation (TLI) was administered to 11 patients who had intractable rheumatoid arthritis that was unresponsive to conventional medical therapy, including aspirin, multiple nonsteroidal antiinflammatory drugs, gold salts, and D-penicillamine. Total lymphoid irradiation was given as an alternative to cytotoxic drugs such as azathioprine and cyclophosphamide. After radiotherapy, 9 of the 11 patients showed a marked improvement in clinical disease activity as measured by morning stiffness, joint tenderness, joint swelling, and overall functional abilities. The mean improvement of disease activity in all patients ranged from 40-70 percent and has persisted throughout a 13-28 month followup period. This improvement permitted the mean daily steroid dose to be reduced by 54%. Complications included severe fatigue and other constitutional symptoms during radiotherapy, development of Felty's syndrome in 1 patient, and an exacerbation of rheumatoid lung disease in another. After therapy, all patients exhibited a profound T lymphocytopenia, and a reversal in their T suppressor/cytotoxic cell to helper cell ratio. The proliferative responses of peripheral blood mononuclear cells to phytohemagglutinin, concanavalin A, and allogeneic leukocytes (mixed leukocyte reaction) were markedly reduced, as was in vitro immunoglobulin synthesis after stimulation with pokeweed mitogen. Alterations in T cell numbers and function persisted during the entire followup period, except that the mixed leukocyte reaction showed a tendency to return to normal values.

Adult↗