Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PHA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMedDate not supplied

Age-related refractoriness of PHA-induced lymphocyte transformation. II. 125-I-PHA binding to spleen cells from young and old mice.

Using 125-I-labelled red kidney bean phytohemagglutinin (125-I-PHA), we have found that spleen cells from old BC3F1 mice bind this plant mitogen equally well, if not better, than spleen cells from young BC3F1 mice, although PHA-induced blastogenesis of spleen cells from old mice is sharply reduced. Analyes demonstrated that there is neither significant alteration of binding affinity nor decreased total number of membrane receptor sites for PHA in senescing mouse spleen cells. The amount of PHA which was initially bound to spleen cells in serum-free medium appeared to be insufficient for a subsequent full stimulation of blastogenesis ([3-H]thymidine incorporation) in either young or old mouse spleen cells; when washed free of unbound extracellular PHA and upon clutivation in serum-containing culture medium, spleen cells rapidly released more than 90% of the bound PHA. Also, temperatures which change cell membrane morphology played a significant role in the binding and retention of PHA. However, no difference was observed between young and old mouse spleen cells in all these phenomena of PHA-cell membrane interaction.

Aging↗
PubMed1990

[Inhibition of PHA-stimulated T cell conditioned medium (PHA-TCM) on the growth of human myeloid progenitor cells (CFU-C)].

Cord blood T cells were enriched by nylon wool colomn, and effects of PHA-stimulated T cell supernatant collected from 18 h to 7 days on the proliferation of CFU-c were studied. The results showed that the supernatant collected at 18 h (PHA-TCM) could significantly inhibit the growth of CFU-c and the inhibition was PHA-TCM dose dependent, suggesting there is a CFU-c inhibitory activity in PHA-TCM. Kinetic studies demonstrated that the activity was decreased in the supernatant collected at 48 h and disappeared at 7 days. On the other hand, unstimulated T cell supernatant and PHA alone had no inhibitory effect on CFU-c growth. Indomethacin did not affect the production of the inhibitory activity and no interferon activity could be detected in PHA-TCM. These suggested that the inhibition was mediated by a non-interferon, non-prostaglandin suppressor. Further studies revealed that the suppressor was a protein stable at 56 degrees C and lost in pH 2 and pH 11 for 3 h, its molecular weight was large than 10,000 dolton.

Adult↗
PubMed1986

Different pathways of human T-cell activation revealed by PHA-P and PHA-M.

Antigen-specific T-cell activation is mediated via the CD3-Ti (antigen receptor) complex, and monoclonal antibodies to both CD3 and Ti cause a rapid rise in intracellular Ca2+. This calcium mobilization is not inhibited by monoclonal antibodies to CD2. The rise in calcium mobilization induced by purified PHA (PHA-P) does not occur in a cell line which lacks CD2 expression, and can be blocked in other T cells by anti-CD2 antibodies. A combination of monoclonal antibodies to different epitopes of CD2 causes calcium mobilization and mitogenesis. Reagent grade PHA (PHA-M) induces calcium moblization in cells that lack CD2, and its effects in other T cells cannot be blocked by anti-CD2 antibodies. The effects of PHA-P and PHA-M are thus mediated predominantly through different activation pathways.

Antibodies, Monoclonal↗
PubMed1989

[Effect of PHA-T cell conditioned medium (PHA-TCM) on leukemic cells].

Cord blood T cells, purified by nylon wool column, were incubated with PHA for 18 hours, and the supernatant were harvested as PHA-TCM. The results demonstrated that PHA-TCM could significantly inhibit the growth of U937 cells and reduce their 3H-TdR incorporation and spontaneous colony formation. After 3-6 days of treatment with PHA-TCM in culture, part of U937 cells became macrophage-like, latex-phagocytic, and capable of reducing NBT dye. On the contrary, HL-60 cells did not respond to PHA-TCM inhibition, indicating the selective effect of PHA-TCM.

Cell Differentiation↗
PubMed1985

Neuroanatomical tracing by use of Phaseolus vulgaris-leucoagglutinin (PHA-L): electron microscopy of PHA-L-filled neuronal somata, dendrites, axons and axon terminals.

Following iontophoretic application of the plant lectin Phaseolus vulgaris-leucoagglutinin (PHA-L) to brain areas of rats, and subsequent immunohistochemistry, reaction product can be observed with the light microscope to fill neurons completely, including their somata, dendrites, dendritic appendages and axons. Moreover, axons often show profuse collateralization and indications of termination, including numerous en passant and terminal varicosities. The present report describes a protocol for combining light microscopic examination of PHA-L-stained neurons and electron microscopy of details of their processes, including the axonal varicosities. The results support the hypothesis that axonal varicosities are the light microscopic representations of synaptic axon terminals seen in electron microscopic preparations.

Agglutinins↗
PubMed1986

Peripheral blood lymphocyte response to exogenous interleukin 2 by PHA-prestimulated and non-PHA-prestimulated cells in patients with cancer.

The study aims were to assess the response of peripheral blood lymphocytes (PBL) of cancer patients to exogenous Interleukin 2 (IL 2) either by PHA-prestimulated or non PHA-prestimulated PBL, and to carry out preliminary experiments for a direct quantitative evaluation of endogenous IL 2 production by PBL cultures of cancer patients in order to define the actual role of IL 2 in the disease. Analysis of PBL subsets was also carried out with monoclonal antibodies in a selected group of patients. A total of 134 patients entered the study. Cancer sites were: larynx 32, breast 36, lung (NSC) 24, colorectal 17 and gynecologic 25. In the former 3 cancer sites staging showed localized or only locally advanced disease, and in the last 2 sites disseminated disease. Our results provided evidence that cancer patients exhibit a T-cell functional immunodepression, which progresses during tumor growth, so that the localized disease shows a low-grade defect, and advanced disease a high-grade defect. Our data also clearly suggested that the factor involved with a primary role in this functional immune impairment is the IL 2 deficiency. A perspective may be drawn on the therapeutic administration in vivo of IL 2 and IL 2-activated lymphokine-activated killer cells in controlled clinical trials of selected groups of cancer patients.

Cells, Cultured↗
PubMed1987

Interleukin 2 (IL 2) relationships with the cancer-related immunodeficiency: in vitro response to exogenous IL 2 by PHA-activated and non PHA-activated peripheral blood mononuclear cells from cancer patients.

The aims of the investigation were: 1) to determine if there are defects in interleukin 2 (IL 2) regulation either on phytohemagluttinin (PHA)-activated or non PHA-activated peripheral blood mononuclear cells (PBMC) in cancer patients, in order to ascertain the role of IL 2 in this disease, and 2) to carry out preliminary experiments for a direct quantitative evaluation of endogenous IL 2 production by PBMC cultures of cancer patients. An assessment of lymphocytes subsets was also performed with monoclonal antibodies in a selected group of patients. A total of 159 patients entered the study. Cancer sites were: larynx, 49; breast, 42; lung (NSC), 25; colorectal, 18; and gynecologic, 25. In the former 3 cancer sites, staging showed localized or only locally advanced disease and in the later 2 sites it showed disseminated disease. Our results provided evidence that the cancer patients exhibit a T cell functional immunodepression, which progresses during tumor growth, so that the localized disease shows a low-grade defect and advanced disease shows a high-grade defect. Our data also clearly suggested that the factor involved with a primary role in this functional immune impairment is the IL 2 deficiency. In our study we have not found a substantial difference of activity between recombinant and nonrecombinant IL 2, although the comparison of the relative activities of the two types of IL 2 is not easy to make, since they are expressed in different ways; however the recombinant one appeared to be slightly more active, probably for the higher purity. Our data also seem to support the perspective of the in vivo therapeutic administration of IL 2 in cancer patients.

Breast Neoplasms↗
PubMed1976

A rapid HLA-D matching method using PHA blasts as responding cells (preliminary data on PHA blasts HLA-D typing).

Day 3-4 PHA stimulated lymphocytes were found to respond against HLA-D without any period of latency, thus allowing a discriminative MLR reading as early as 24-48 h. The test is therefore characterized by the minute number of responding cells necessary (5 X 10(3)), a one-way reaction without additional treatment of the stimualtion normal lymphocytes (5 x 10(4)), and the rapid obtaining of data. We found the preliminary data testing its concordance with classical HLA-D typing encouraging and worthy of being tested on a larger scale. Using mitogen stimulated recipient cells stored frozen, HLA-D matching with potential donors was found to be feasible within 24-48 h. The mechanism of such a prompt response by mitogen stimulated lymphocytes is unknown but appears to be independent of the nature and dose of a given mitogen.

HLA Antigens↗
PubMed1985

Phytohemagglutinin (PHA)-resistant Chinese hamster ovary cell mutants acquire sensitivity to the lectin after fusion with liposomes containing PHA receptor glycoproteins.

Phytohemagglutinin receptor glycoproteins have been inserted into phospholipid vesicles and these have been fused with phytohemagglutinin-resistant chinese hamster ovary cells. Our results show that the fused cells acquire "neoreceptors" for the lectin phytohemagglutinin. Fluorescence activated cell sorting analyses show that approximately 40% of the cells fused with the receptor-containing vesicles. Studies with 125I-labelled lectin showed that fused cells bound three times more ligand than untreated mutant cells. Furthermore, lectin receptors were functionally inserted in the mutant cell plasma membrane. Fused cells cultured in the presence of lectin (200 micrograms ml-1) lost rapidly (8 hours or less) their ability to incorporate [3H] thymidine. Whereas mutant cells cultured for 16 hours in the presence of 50-400 micrograms ml-1 of lectin remained viable, fused cells showed a 45% decrease in 3H-labelled nucleotide incorporation. The method described here should be of general applicability for the study of lectin-dependent cytotoxicity in chinese hamster ovary cell lines.

Animals↗