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T J Linna

Publications and source records attributed to T J Linna.

At least 19 recordsLinked to original sources
PubMed1999

Four-year follow-up of mycophenolate mofetil for graft rescue in liver allograft recipients.

BACKGROUND: Mycophenolate mofetil (MMF) has been shown to have promise in short-term liver transplantation graft rescue studies. The purpose of this study was to evaluate the long-term efficacy and safety of MMF in liver transplant patients who had failed cyclosporine (CsA)-based conventional immunosuppression. METHODS: Nineteen orthotopic liver allograft recipients were converted from azathioprine to MMF in combination with CsA and prednisone in this prospective, open-labeled, single-center, graft rescue, pilot study. Six patients were taken off CsA when MMF was initiated. A 4-year patient follow-up is reported here. Patients were considered to have failed CsA-based immunosuppression either for refractory rejection, chronic rejection, or severe CsA neurologic toxicity. RESULTS: Twelve patients had complete histologic resolution, two had partial resolution, and three had worsening of their rejection. Thirteen patients had a complete biochemical response; one had a partial response and four had worsening of their rejection. Two patients had no histologic and one no biochemical follow-up. Of the six patients treated with MMF and prednisone alone, four had complete resolution of rejection without recurrence. The majority of adverse reactions were gastrointestinal [nausea and/or vomiting (n=5); diarrhea (n=8); gastritis, duodenitis, or esophagitis (n=4); and ulcers (n=2)] or bone marrow suppressive [leukopenia (n=9), anemia (n=6), and thrombocytopenia (n=5)]. CONCLUSIONS: MMF seems to be an effective alternative immunosuppressive in patients failing CsA-based conventional therapy. MMF may be of particular benefit in patients who do not tolerate CsA or tacrolimus. The long-term safety profile is similar to that of other immunosuppressives.

Adult↗
PubMed1997

The regulation of pHi in osteoclasts is dependent on the culture substrate and on the stage of the resorption cycle.

The present study was performed to clarify the role of vacuolar H+-ATPase in the regulation of the intracellular pH (pHi) in osteoclasts. Bafilomycin A1 or amiloride were added to rat osteoclast cultures to block the H+-ATPases and Na+/H+-exchangers, respectively. Addition of 10(-8) M bafilomycin A1 to osteoclasts cultured on bone induced a rapid decrease of the pHi, while addition of amiloride had only a minor effect. The response to bafilomycin A1 appeared simultaneously with resorption activity and was abolished when resorption was inhibited by calcitonin. Osteoclasts on bone recovered from acid loading caused by propionate in the presence of amiloride, while bafilomycin A1 inhibited this recovery almost completely. The pHi of osteoclasts cultured on glass responded to the addition of amiloride, but was not effected by even high concentrations of bafilomycin A1. In contrast, as little as 10(-10) M bafilomycin A1 caused accumulation of large vesicles in the cytoplasm.

Amiloride↗
PubMed1989

Systemic interleukin I administration suppresses arachidonic acid-induced ear oedema in the mouse.

Recombinant human interleukin 1 beta (IL-1 beta), given intraperitoneally to mice as a single injection, significantly suppressed the development of arachidonic acid (AA)-induced ear oedema. This effect was noted 2 h after administration and for at least 5 days afterwards. IL-1 beta was effective in the dose range of 250 ng-20 micrograms/mouse. Injection of IL-1 beta per se resulted in erythema of the ears, and thus, IL-1 beta has the capacity not only to induce and augment but also to suppress inflammatory responses. Indomethacin administered as subcutaneously-implanted pellets did not influence the IL-1 beta induced-ear erythema, but suppressed to some extent the effect of IL-1 beta on the AA-induced ear oedema.

Animals↗
PubMed1989

Enhancement of natural killer cell activity by Nocardia opaca fractions.

Three molecules derived from Nocardia opaca bacteria, NDCM, NWSMP, and PG, have been shown to express immunomodulating properties. The present study was aimed at assessing the effects of these derivatives on natural killer (NK) activity. Two experimental protocols were adopted, consisting of incubating whole or Percoll fractionated NK cells in vitro with those substances, and the other in which the derivatives were administered in vivo to mice and the activity assessed later. Incubation of spleen cells in vitro with NWSMP or its precursor NDCM promoted NK activity. This effect could be observed after only 2 h of incubation and continued until day 2. Percoll fractions 1-3, which contain most of the NK activity, were enhanced to a similar extent. Band 4, which is usually devoid of such activity, remained unresponsive even after contact with the N. opaca derivatives. PG was practically ineffective upon all the subsets. The results of experiments in vivo correlated with those obtained in vitro in that NWSMP and NDCM, but not PG, promoted NK activity. Bands 1-3 were similarly enhanced, the effect was observed after short treatment times, and could be partially cancelled by the concomitant administration of anti-interferon antibodies (anti-IFN Ab). All these findings suggest that the promoting effects of N. opaca derivatives are mediated through alpha/beta IFN. In contrast to the results observed on spleen NK cells, NK cells from the peritoneum displayed susceptibility mainly to PG, and much less to NWSMP or NDCM. The administration of PG to mice in vivo had a particularly marked promoting effect upon the cytotoxic activity of peritoneal cells. One logical explanation for the difference observed between PG and NWSMP or NDCM may be related to the specific IFN inducing properties of these compounds as well as to the different responsiveness of the NK cells present in the spleen and peritoneal cavity.

Animals↗
PubMed1988

Unfractionated spleen cells but not natural killer (NK) cells from RFM donors prevent the progression of host-versus-graft disease in murine RFM/(T6 x RFM)F1 chimeras.

Host-versus-graft (HVG) syndrome is the fatal allogenic disease which develops in susceptible strains of inbred mice following their perinatal inoculation with related F1 hybrid spleen cells. Deaths are caused by pathogenic immune complexes. It is thought that the antibody components of these complexes are produced by F1 donor B cells stimulated by the allogenic HVG reaction. To complement previous work that showed that lethal disease could be prevented if the HVG response was suppressed, the present studies tested whether or not it could also be prevented by augmenting HVG reactivity with the adoptive transfer of spleen cells syngenic with the host. The data show that unfractionated RFM spleen cells given on Days 13-14 prevented lethal disease in 86% of RFM/(T6 x RFM)F1 chimeras. Successful therapy was associated with the suppression of formation of nephropathic-immune complexes, and with the rejection of F1 donor cells or their gradual replacement by host cells. RFM spleen cells enriched for NK activity by a new improved method not only failed to prevent HVG disease but appeared to exacerbate it. This was also true of spleen cells that had been activated in vitro for 3 days with IL-2, a procedure that greatly enhanced their cytolytic activity against YAC-1 targets. It is suggested that therapy with NK cells failed, even after IL-2 activation, because they had no effect on proliferating and antibody-forming F1 donor cells that had engrafted in large numbers in the lymph nodes of the RFM hosts.

Animals↗
PubMed1986

Identification of the human T-lymphocyte protein-tyrosine kinase by peptide-specific antibodies.

We have recently cloned a cDNA from the human T-cell leukemia, JURKAT, having homology with the src-like family of protein-tyrosine kinases. We have made rabbit polyclonal antibodies against the synthetic peptide CKERPEDRPTFDYLRSVLEDFFTATEGQYQPQP (cys-33-pro) deduced from the carboxy-terminal amino acid sequence predicted by the JURKAT cDNA. In this report, we demonstrate that these antibodies immunoprecipitate the protein-tyrosine kinase activity from solubilized membrane extracts from JURKAT T-leukemia cells and from human peripheral blood T-lymphocytes from normal donors. A 58 kd protein, exhibiting protein-tyrosine kinase activity, was specifically immunoprecipitated in both cases. The antibodies failed to crossreact with pp60c-src from human platelets, but did crossreact with the murine T-lymphocyte protein-tyrosine kinase, pp56T-cell.

Animals↗
PubMed1986

Human T lymphocytes express a protein-tyrosine kinase homologous to p56LSTRA.

We have used oligonucleotide probes, based on a portion of the p60v-src autophosphorylation sequence, Glu-Asp-Asn-Glu-Tyr-Thr, to identify and characterize a cDNA from the human T-leukemia cell line, JURKAT. The JURKAT cDNA (designated ptk-JURKAT) was homologous to but distinct from the src, yes and fgr oncogenes, which encode protein-tyrosine kinases (ATP:protein phosphotransferase, EC 2.7.1.37). The ptk-JURKAT cDNA hybridized with a 2.2 kb RNA transcript from JURKAT cells and the human T-cell lymphoma line, MOLT-4, but failed to identify any transcript in two human B-cell lymphoma lines or a human erythroid-myeloid leukemia line, K562. Recently the nucleotide sequence has been established for the murine lymphocyte protein tyrosine kinase, p56LSTRA. The ptk-JURKAT cDNA appears to encode the human homolog of p56LSTRA.

Amino Acid Sequence↗
PubMed1986

Suppression of cytolytic T-cell activity by staphylococcal enterotoxin B-induced suppressor cells: role of interleukin 2.

We have previously shown that staphylococcal enterotoxin B (SEB) is a potent inducer of suppressor T cells which function to inhibit antibody production in vitro. In the present paper we extend these studies and show that the SEB-induced suppressor cells also inhibit the development of cytotoxic lymphocytes in mixed-lymphocyte reaction (MLR) cultures. Since further analysis also showed that the level of interleukin 2 (IL-2) in cultures of SEB-primed cells was significantly reduced, experiments were carried out to determine the role of IL-2 in the inhibition of cytotoxic cell activity. Attempts to neutralize the suppression by supplementing MLR cocultures with delectinated supernatants from concanavalin A (Con A)-stimulated rat splenocytes were not successful. In addition, MLR cocultures supplemented on Day 0 with 50 units of affinity-purified IL-2 were also suppressed. Further analysis showed that the IL-2 activity in the supplemented MLR cocultures containing suppressor cells were significantly reduced by Day 3. However, repeated supplementation of the MLR cocultures with exogenous IL-2 was successful in achieving (and maintaining) "normal" levels of IL-2. The cytotoxic cell activity in these MLR cocultures remained suppressed. These results suggest that the inhibition of cytotoxic cell activity by SEB-induced suppressor cells is independent of IL-2 levels in the MLR coculture.

Animals↗
PubMed1985

High tyrosine-specific protein kinase activity in normal human peripheral blood lymphocytes.

Tyrosine-specific protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) activity was measured in normal human nonadherent peripheral blood lymphocytes using synthetic peptide substrates having sequence homologies with either pp60src or c-myc. A high level of tyrosine-specific protein kinase activity was found associated with the cell particulate fraction (100 000 X g pellet). High-pressure liquid chromatography and phosphoamino acid analysis of the synthetic peptide substrates substantiated the phosphorylation of tyrosine residues by the particulate fraction enzyme. The human enzyme was also capable of phosphorylating a synthetic random polymer of 80% glutamic acid and 20% tyrosine. Enzyme activity was half-maximal with 22 microM Mg X ATP and had apparent Km values for the synthetic peptides from 1.9 to 7.1 mM. The enzyme preferred Mg2+ to Mn2+ for optimal activity and was stimulated 2-5-fold by low levels (0.05%) of some ionic as well as non-ionic detergents including deoxycholate, Nonidet P-40 and Triton X-100. The enzyme activity was not stimulated by N6;O2'-dibutyryl cyclic AMP (100 microM), N6;O2'-dibutyryl cyclic GMP (100 microM), Ca2+ (200 microM), insulin (1 microgram/ml) or homogeneous human T-cell growth factor (3 micrograms/ml) under the conditions used. Alkaline-resistant phosphorylation of particulate proteins in vitro revealed protein bands with Mr 59 000 and 54 000 suggesting that there are endogenous substrates for the human lymphocyte tyrosine protein kinase.

Blood Proteins↗
PubMed1985

Decreased natural killer-type activity of spleen cells against immature thymocytes in autoimmune strains of mice.

Recently we have reported that normal natural killer (NK)-enriched murine spleen cells have the capacity to lyse immature thymocytes of syngeneic or allogeneic origin. The studies presented in this paper show a different pattern of NK-type cytolysis and thymocyte sensitivity in mice which later in life develop autoimmune disease. Such mice appeared to have reduced effector NK capacity and thymocytes from these mice seemed to have reduced sensitivity as targets. This may allow presence and persistence of autoreactive T cell subpopulations which would normally be eliminated.

Animals↗
PubMed1985

Natural killer-type lysis of thymocytes from young mice by normal spleen cells in vitro.

Normal spleen cells from 6- to 10-week-old mice, enriched for natural killer (NK) cells on a discontinuous polyvinylpyrrolidone-silica (Percoll) gradient, lyse thymocytes of young mice (less than or equal to 19 days old) in a short-term 51Cr release assay. The highest NK-type activity was found in band 3 (density less than or equal to 1.077 g/ml) of a four-step gradient. In some experiments band 2 (density less than or equal to 1.070 g/ml) also showed NK activity. Activity was not unequivocably detectable in cells before separation or in bands 1 and 4. These results also show that the thymocyte sensitivity is dependent on the age of the target cell. Sensitivity of very young thymocytes (less than or equal to 7 days old) was higher than that of thymus cells from 8- to 19-day-old donors. Moreover, it seemed that syngeneic target thymocytes were lysed more effectively than allogeneic. Thus, an NK-type cell population may have the ability to lyse immature thymic target cells at an early stage of their differentiation. This could be of importance as a physiological mechanism for controlling the T cell repertoire and its reactivity.

Aging↗
PubMed1984

Enrichment of mouse splenic natural killer cells using discontinuous polyvinylpyrrolidone silica (Percoll) gradients.

A simple and rapid method is reported here for enriching murine spleen cells with natural killer (NK) function as assessed by short-term cytolysis assay of 51Cr-labelled YAC-1 lymphoma target cells. The established method used for the enrichment of NK reactive cells, including large granular lymphocytes (LGL) from human and rat peripheral blood lymphocytes, does not substantially enrich for mouse splenic NK cell activity. A reproducible procedure for enriching mouse splenic NK cells has been developed using a four- or five-step discontinuous Percoll gradient in the density range of 1.062 g/ml (top) to 1.092 g/ml (bottom) and osmolarity (310-340 mOsm/kg) nearer to that of mouse blood and tissue. A four- to 25-fold (usually about nine-fold) increase in NK cell activity, consisting of 50-100% of the recovered lytic unit activity, is found in which are the cells forming band 3, approximately 10% of the recovered cell number. This cell population with enriched NK cell activity has a characteristic density less than or equal to 1.077 g/ml, but more than 1.070 g/ml when centrifuged under appropriate conditions. Similar enrichment was obtained with a four-step gradient at an uniform osmolarity of 320 mOsm/kg throughout. Although the lymphocytes in band 3 show relatively little heterogeneity in appearance, only a minor population of the cells contain granules.

Animals↗
PubMed1983

Extremely high levels of natural killer cells in angioimmunoblastic lymphadenopathy.

Analysis of peripheral blood leukocytes from a patient with angioimmunoblastic lymphadenopathy using monoclonal antibodies and the fluorescence-activated cell sorter showed an unusually high proportion of cells that were OKT10+OKM1+63D3-. Since a large proportion of the large granular lymphocytes associated with natural killing in humans bears this surface phenotype, both blood and lymph node cells were subsequently tested for cell-mediated cytotoxicity in natural killer (NK)-cell assays. Following chemotherapy, both cells bearing the NK surface phenotype and the NK cytotoxicity disappeared and a population of cells, bearing none of the typical lymphocyte or monocyte markers, became dominant. At this point the patient was diagnosed as having immunoblastic sarcoma and shortly thereafter succumbed to his disease. In the few cases where extremely high levels of NK activity have been reported, the tumor cells themselves have been responsible for cell-mediated cytotoxicity. In this case, the final tumor population had no NK activity. Thus either a subpopulation of cytotoxic tumor cells was destroyed by chemotherapy or the patient had expanded numbers of NK cells reacting against his tumor prior to therapy.

Antibodies, Monoclonal↗