Gangliosides of murine T lymphocyte subpopulations

Gangliosides from murine T lymphoblasts were analyzed by high-performance thin-layer chromatography followed by in situ neuraminidase treatment and immunostaining of the resulting asialogangliosides and compared with those from thymocytes and cloned T lymphocytes with defined functions. The ganglioside IVNeuGc/Ac-GgOse5Cer (GalNAc-GM1b), a marker for T lymphoblasts [Müthing, J., Egge, H., Kniep, B., & Mühlradt, P. F. (1987) Eur. J. Biochem. 163, 407-416], was found only in small amounts as the N-acetylated species in gangliosides from thymocytes and a cytolytic T cell clone. Two helper clones expressed this ganglioside like T blasts. The structures of the two major disialogangliosides from T blasts, IVNeuAc,IIINeuAc-GgOse4Cer (GD1 alpha type) with C24:0/24:1 and C16:0 fatty acids, were elucidated by neuraminidase treatment and immunostaining and by fast atom bombardment mass spectrometry. Gangliosides of this type were detected in thymocytes only in minor amounts, whereas GM1b-type gangliosides prevailed in cells from this organ. Analysis of the T lymphoblast gangliosides from six genetically unrelated mouse strains showed that terminally sialylated GgOse4Cer (GM1b), IVNeuAc-GgOse5Cer (GalNAc-GM1b), and IVNeuAc,IIINeuAc-GgOse4Cer (GD1 alpha) were conserved structures in all strains examined. We conclude that maturation or stimulation of T cells may be correlated with elongation of a common GM1b-type precursor structure resulting in GalNAc-GM1b or GD1 alpha-type gangliosides.     

Random recirculation of small T lymphocytes from thoracic duct lymph in the mouse

The migration of ⁵¹Cr-labeled nylon-wool separated mouse thoracic duct T cells has been followed in order to determine whether there is a circulation of small (nondividing) T cells through the small intestine. Approximately 6% of the injected dose of T-TDL localized in the small intestine (minus Peyer's patches). Experiments revealed that this gut-localizing cell population consisted almost entirely, if not exclusively, of lymphoblasts present in mouse T-TDL. When lymphoblasts and small lymphocytes from mouse T-TDL were separated by velocity sedimentation, and the migration of separated fractions was studied, we found large cells (66% blasts) migrated well to the gut but poorly to the lymph nodes, whereas small cells (2% blasts) showed minimal migration to the gut but localized randomly in lymph nodes and spleen. The in vivo distribution of small cells from T-TDL was similar to that of T-PLN. Furthermore, the recirculatory patterns of both ⁵¹Cr-labeled T-TDL and T-PLN were found to be identical as accessed by their rate of recovery in the thoracic duct lymph of recipient mice. These results support the notion that the vast majority of T-TDL and T-PLN are part of a common pool of recirculating T cells which recirculate randomly through lymph nodes and spleen and not the small intestine.     

Differentiation of human T and B peripheral blood lymphocytes by high-resolution cell image analysis

Automated cell image analysis of light and electron microscopic pictures was used for differentiation of nonlabeled lymphocytes in blood smears and in smears of purified lymphocyte suspensions. The percentages of T and B lymphocytes were determined by a two-step rosette assay with sheep red blood cells (T cells) and an immunofluorescence assay with FITC-labeled antihuman globulin (B cells). Images from 1,400 Feulgen-stained and 12,000 Pappenheim-stained cells were analyzed. Various classification methods allowed two lymphocyte subpopulations to be discriminated at the light and electron microscopic levels on the basis of different visual and subvisual morphologic features. As found by immunologic methods, morphologically determined subpopulations corresponded to T and non-T cells, with no further differentiation of non-T cells into B or null cells possible. The results allow the conclusion that there are morphologic differences between human T and non-T cells, with the differences distinguishable from individual variations as well as from alterations induced by sample preparation.     

Cyclic AMP phosphodiesterase activity of murine T and B lymphocytes.

Recent evidence suggests that adenosine 3′,5′-monophosphate (cyclic AMP) may play a role in lymphocyte responses. The nature of this role is yet unclear since it has been reported that increases in intracellular cyclic AMP can both inhibit and enhance immune functions. In an attempt to determine how lymphocyte cyclic AMP metabolism is regulated we have measured cyclic nucleotide phosphodiesterase in populations of murine T and B lymphocytes. Results indicate that the enzyme activity in B cells was over fourfold higher than that found in thymocytes. Further analyses by preparative polyacrylamide gel electrophoresis revealed that these cell populations contained different multiple forms of the enzyme.     

Activation of murine B lymphocytes by suramin

Suramin stimulated DNA synthesis in spleen cell cultures of all inbred strains of mice tested, including, for example, CBA, DBA/2, C57BL/6, and the lipopolysaccharide (LPS)-nonresponsive strain C3H/HeJ. The cells responding to the drugs were removed by passage through nylon wool columns, but they were not eliminated by in vivo treatment of the mice with anti-Thy 1.2 antibody. Spleen cells of homozygous nude mice (C57BL/6 or BALB/c background) were as reactive as those of their heterozygous littermates. Collectively the data show that suramin is a B-cell mitogen in the mouse.     

Interactions between B lymphocyte subpopulations. Augmentation of the responses of resting B lymphocytes by activated B lymphocytes

Mouse B lymphocytes were fractionated from normal T lymphocyte-depleted spleen cell populations using discontinuous percoll gradients and were stimulated with rabbit F(ab')2 anti-mouse mu-specific antibodies (anti-mu) plus the supernatant of Con A-stimulated rat spleen cells (SN) as a source of lymphokines. The responses of small (mean volume 120 mu 3), dense (greater than 1.087 specific gravity), resting (least spontaneous thymidine incorporation) B lymphocytes were augmented by irradiated (4000 rad), larger (mean volume greater than 170 mu 3), less dense (less than 1.081 specific gravity), activated (greater spontaneous thymidine incorporation) B lymphocytes. Proliferation was augmented 2- to 4-fold and polyclonal antibody-forming cell responses three- to sixfold. Maximal augmentation of the responses of 5 X 10(4) resting B cells was obtained with 10(4) activated B cells. Augmenting activity was specific for activated B lymphocytes in that responses were not augmented by irradiated thymocytes, T lymphoblasts, macrophages, or additional supernatant. B lymphocytes activated in vitro by LPS or anti-mu also had augmenting activity. Augmentation of responses was maximal only when activated B lymphocytes were added simultaneously with anti-mu. The interaction between activated and resting B lymphocytes did not appear to be genetically restricted. Interestingly, the augmenting activity of activated B cells could be reconstituted by a combination of supernatant and cell membranes from these cells but not by either alone, suggesting that two components are required, one soluble and the other membrane-bound. Thus, a functional interaction has been demonstrated between B lymphocyte subpopulations which differ in their state of activation, and this interaction appears to involve a novel mechanism of action.     

IgM complex receptors on subpopulations of murine lymphocytes.

Murine lymphocytes from spleen, lymph node, and thymus were examined for IgM complex receptors. Lymphocytes from all three organs were found to bind SRBC sensitized with IgM from various sources including: primary anti-SRBC serum, murine and rabbit anti-Escherichia coli LPS sera, and a murine IgM myeloma (MOPC 104E). Rosette formation by lymphocytes with IgM-sensitized SRBC was inhibited by soluble antigen-IgM complexes but not by IgM or antigen alone. Rosette formation was also inhibited by human IgM (Fc)5mu but not by Fab mu. Antiserum and complement treatment of the cells and subsequent recovery of the viable cells by trypsinization, filtration, and washing revealed the IgM rosette-forming cell (RFC) in the thymus to be a T cell. Spleen on the other hand was found to contain both B and T cells capable of binding IgM sensitized SRBC. Removal of both B and T cells from spleen cell suspensions eliminated all IgM RFC. The IgM complex receptor was found to be trypsin insensitive. Anti-Ig column fractionation enriched IgM RFC in spleen and lymph node suspensions passed through the columns, whereas cells bearing surface Ig, IgG complex receptors, and C3 receptors were retained in the columns.     

Different expression patterns of TRP genes in murine B and T lymphocytes

A prolonged increase in the intracellular calcium concentration ([Ca2+]i) is essential for lymphocyte activation that includes cell proliferation and differentiation. This increase in [Ca2+]i results from Ca2+ release from the intracellular store and the subsequent Ca2+ influx from the extracellular environment via calcium channels located on the plasma membrane. Although transient receptor potential (TRP) channels have been reported to play important roles in the [Ca2+]i increase in lymphocytes, the function of these channels in lymphocyte activation remains unknown. Here, we report the comprehensive expression profile of TRP channel gene families including TRPC, TRPV, and TRPM in the murine immune system. RT-PCR analysis revealed different expression patterns of the TRP channel genes in B and T lymphocytes isolated from the spleen. Therefore, our results provide an appropriate reference of TRP gene expression in murine lymphocytes.     

Functional properties of T and B cells isolated by affinity chromatography from rat thoracic duct lymph.

Rat thoracic duct lymphocytes (TDL) were separated into two fractions by passing the cells through a column of rabbit anti-rat F (ab′)₂ antibody coupled to Sephadex G-200. Cells with readily detectable surface immunoglobulin (Ig) were retained on the gel, whereas those without surface Ig were recovered in the effluent. Adherent cells were retrieved by eluting the column with rat Ig. Both dividing and nondividing lymphocytes were separated by this procedure. The adherent and non-adherent fractions contained functionally active lymphocytes as judged by a thymidine incorporation technique and the immunological performance of the cells after transfer to normal recipients. Antibody forming cells and B memory cells were concentrated in the adherent fraction. The non-adherent fraction contained antigen-sensitive T cells which initiate graft versus host reaction and specifically sensitized lymphocytes of the kind which transfer resistance to L. monocytogenes.     

Serologically defined subpopulations of human T lymphocytes.

Several rabbit antisera to T cells obtained from various sources (thymus, peripheral blood, brain, T-derived leukemias) were studied with the aim to obtain reagents specific for a subset of T cells. Sera were first absorbed on human tissues and B cells; thereafter these T cell-specific sera were additionally absorbed with T cells of different origin and especially with leukemic T cells, which are likely to represent a clonal expnasion of a subset of T cells with potentially unique antigenic markers. Three antigenically distinct subpopulations of T cells were delineated. The relationship of these subsets with previously defined human T cell subpopulations (T subsets with a receptor for the Fc or IgG or IgM or with a receptor for a lectin from wheat germ agglutinin) was investigated.     

Differentiation of murine B cells induced by chondroitin sulfate B

A two-step culture system was used to investigate the role of chondroitin sulfate (CS) B, which is mitogenic to B cells, in differentiation of B cells. Mouse spleen B cells were incubated for 3 days with CSB in the presence of interleukin (IL)-4 and IL-5. After washing, the cells were replated at 10(5) viable cells/well and recultured without CSB in the presence of IL-4 and IL-5. CSB dose-dependently increased IgM production, the greatest enhancement being 450%. Dextran sulfate had a similar effect, whereas other glycosaminoglycans, CSA, CSC, heparin and hyaluronic acid, were marginally effective. Treatment of B cells with CSB resulted in increases in the number of IgM-secreting cells and numbers of CD138-positive cells and CD45R/B220-negative cells. CSB-induced IgM production was inhibited by the protein kinase C (PKC) inhibitor GF109203X but not by the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin. These results demonstrated that CSB promoted differentiation of B cells in the presence of IL-4 and IL-5 and suggested that PKC but not PI3K is crucial for CSB-induced IgM production.     

Differential susceptibility of murine T and B lymphocytes to freeze-thaw and hypotonic shock

Experiments were carried out to determine if thymic-derived lymphocytes (T-cells) could be differentially damaged by hypotonic and/or freeze-thaw stress. The uptake of ³H-thymidine after stimulation of murine spleen cells with phytohemagglutinin-P (PHA-P) or bacterial endotoxin (LPS) was used as an indicator of recovery. Optimal freezing and thawing techniques showed that 100% of LPS-responsive cells could be recovered, compared to 65% of PHA-responsive cells. These differences could be increased by treatment of spleen cells with 0.17 m NH₄Cl prior to freezing and thawing. This represented a recovery of 50% of LPS-responsive cells and less than 10% of PHA-responsive cells. A similar effect could be obtained by treating NH₄Cl-treated spleen cells with distilled water prior to culture. It is hypothesized that T-cells are more susceptible to osmotic damage than B-cells due to their differences in membrane characteristics.     

Bronchopulmonary lymphocytes and their B and T subpopulations in control and experimental influenza infected mice]

Immunofluorescent studies showed that, whereas the total number of lymphocytes was still increased on the third and fourth weeks of experimental airborne influenza, the B/T cell ratio remained in the same range as in control animals. This ratio is comparable to results with mouse peripheral lymph nodes.     

Maturation of b lymphocytes in rates. III. Two subpopulations of memory B cells in the thoracic duct lymph differ by size, turnover rate, and surface immunoglobulin.

We examined the ability of large and small thoracic duct cells obtained from Lewis rats primed to DNP to restore the adoptive secondary anti-DNP response in irradiated syngeneic hosts given an excess of T helper cells. The large cells were four to five times more active on a per cell basis than were the small cells. However, the large cells constitute only 7 to 8% of the thoracic duct cells and, therefore, make a minor contribution to the restorative activity of the unfractionated cells. Pretreatment of thoracic duct cell donors with high specific activity 3H-TdR for 48 hr before cannulation markedly reduced the memory B cell activity of the large cells, but had little effect on that of small cells. In addition, the activity of the large cells diminished with time after primary immunization, but that of the small cells remained stable. Immunofluorescent staining of the large and small cells for surface IgM and IgG, and subsequent sorting on the fluorescence-activated cell sorter (FA CS), showed that surface IgM was present on large memory B cells, and that IgG was present on small memory B cells. The experimental results suggest that two subpopulations of memory B cells in the thoracic duct lymph differ by size, rate of turnover, persistence after primary immunization, and class of surface IgG.     

Human B and T lymphocytes convert leukotriene A4 into leukotriene B4

Incubation of human tonsillar B lymphocytes and peripheral blood T lymphocytes with leukotriene A4 led to the formation of leukotriene B4. The purity of these cell suspensions was more than 99%, containing less than 0.5% monocytes. Incubation of purified B or T lymphocytes with the calcium ionophore A23187 did not lead to the formation of any detectable amounts of leukotrienes. Several established cell lines of B and T lymphocytic origin were also found to convert leukotriene A4 into leukotriene B4, showing that monoclonal lymphocytic cells possess leukotriene A4 hydrolase activity.