Isolation of heterogeneous lymphocytes according to their cellular densities by multilayer centrifugation and detection of the separated fraction contaoning the immunological memory cells

Lymphocytes bursting induced by heparin, dextran sulfate and other polyanions

We found that high molecular polyanions (PAs) such as dextran sulfate and heparin burst some damaged or dead lymphocytes in lymphocyte suspension isolated from living bodies, and clarified morphologically the mechanism involved in this. PAs passed through damaged cell membranes and reached the chromatin in the nucleus. Electron micrographs suggested that they then extracted histones from the chromatin and formed complexes with them, and that freed DNA formed a gel binding with the complexes in the nucleus, and the nucleus became swollen and burst due to the gel swelling pressure. To support this conjecture, the nuclei of lymphocytes were stained with propidium iodide and exposed to light to stabilize them. The stabilized nuclei were not swollen after the addition of PAs and the lymphocytes did not burst. The lymphocyte bursting effect of PAs was attributed to their negative charges which could not destroy intact cells. At this point, PAs are different from sodium dodecyl sulfate which destroys intact cells completely.

Effects of methyl mercuric chloride and sulfhydryl inhibitors on phospholipid synthetic activity of lymphocytes

The effect of methyl mercuric chloride on the activity of phospholipid synthesis of rat lymph node lymphocytes was compared with that of sulfhydryl inhibitors. Measurement of the radioactivity of [14C]oleic acid and [14C]acetate incorporated into lecithin of cells during short-term incubation showed that all the inhibitors tested similarly reduced the incorporation. However, methyl mercuric chloride (MMC) was the strongest inhibitor, being effective at 4 microM and causing more than 80% decrease at 20 microM. Inhibition by the sulfhydryl inhibitors, at less than 40 microM, ranked as follows: N-ethylmaleimide greater than alpha-chloroacetophenone greater than hydroquinone greater than iodoacetamide. MMC also obstructed the enhancement by phytohemagglutinin of [14C]oleic acid incorporation into lecithin. MMC was effective at 2 microM, while the other agents had little or no effect at this concentration. Further investigation suggested that inhibition of phospholipid synthesis did not depend on reduced incorporation of oleic acid into the cellular membrane but on decreased turnover of the fatty acid into phospholipids after the incorporation. The viability of lymphocytes incubated with the agents was measured by trypan blue dye-exclusion test. More than 90% of the cells treated with MMC at a concentration as low as 20-40 microM died, but the SH inhibitors, including NEM which greatly inhibited the phospholipid synthesis, produced few cell deaths at these concentrations. These observations show that the SH inhibitors affect enzymes in phospholipid synthesis, whereas MMC not only inhibits the enzymes but kills cells.

Maturational impairment of thymic lymphocytes in streptozotocin-induced diabetes in rats

Streptozotocin (STZ)-induced diabetes in rats was associated with marked decreases in thymus weight and the number of thymic lymphocytes. Histologically, the cortical lymphocytes which were present near the cortico-medullary junction in the thymus seemed to be reduced selectively in the STZ-induced diabetes. Rosette-forming cells, which bind to guinea pig erythrocytes in the presence of fetal calf serum, were also significantly decreased. Insulin treatment allayed these intrathymic changes. Preincubation of thymic lymphocytes from diabetic rats with thymosin fraction 5 significantly enhanced the percentage of rosette-forming cells to near the control level. These results suggest that a maturational impairment of thymus cortical lymphocytes may be caused in STZ-induced diabetes with hypoinsulinemia and it may be intimately related to reductions in thymus weight and the number of thymic lymphocytes.

T cell subsets in the tonsil in relation to age analyzed with monoclonal antibodies (anti-leu antibodies) and fluorescence activated cell sorter (FACS)

The ratio of the cells reacting to anti-leu 1, 3a and 4 antibodies is as low as that of T cells in the tonsil to those in the peripheral blood. The number of the tonsillar cells reacting to anti-leu 2a and 7 antibodies is still smaller. Fluorescence intensity of tonsillar lymphocytes reacting to leu (1, 2a, 3a, and 4) antibodies is lower than that of peripheral blood lymphocytes. Adult tonsillar lymphocytes have higher ratios of the cells reacting to anti-leu 1, 2a, 3a, 4 and 7 antibodies than child tonsillar lymphocytes and fluorescence intensity of the cells reacting to these anti-leu antibodies tended to be higher in adult tonsillar lymphocytes. These findings suggest less cytotoxic/suppressor T and NK/K function cells in the tonsil than in the peripheral blood. From these, it is conceivable that the tonsillar lymphocyte constitution becomes closer to that of peripheral blood as the child grows up. Further, immature T cells are present in the tonsil, though in a small number. This tendency is stronger in children than in adults.

Studies on the cell-mediated immune response of tonsillar lymphocytes with regard to the clinical course and patient's age

There was no statistically significant difference in the intensity of the cell-mediated immune response of tonsillar T cells among different pathological conditions of the tonsils nor among different age groups. The tonsillar cell population of the adult was smaller than that of the child. Tonsillar cells were separated into 3 fractions with different specific gravities. In tonsillar cells from adults, fraction III consisting mainly of small lymphocytes with a high specific gravity occupied a larger portion than in those from children. Fraction I consisting of cells with a low specific gravity had a greater number of cells in the swollen tonsils of children than in the tonsils of adults. However, the absolute numbers of the cells in fraction III in adults and in children were nearly the same. The proportion of T cells in fraction III was higher than in fraction I. Hence, the proportion of T cells in adults' tonsils is higher than in children's tonsils. The cells composing fraction I include some cells that have undergone blastoid transformation in response to various stimuli and some lymphoid cells that are ontogenetically immature T cells, besides mature T cells. The cells composing fraction III include fully mature T cells and the total cell population of fraction III does not differ significantly with age. It seems likely that the child's tonsil contains a larger number of cells under antigenic stimulation or in preparation for immune response than does the adult's tonsil.

A rapid method for measuring the phospholipid synthetic activity of incubated lymphocytes

A rapid and simple method for estimating the phospholipid synthetic activity of incubated lymphocytes by a Florisil column technique following the uptake of 14C-oleic acid was established. Stimulation of phospholipid synthesis by PHA and inhibitions caused by Tween 20 or Tween 80 and heating were evaluated easily with this method.

Studies on the capacity of human tonsillar lymphocyte subpopulations to produce interferon

Tonsillar lymphocytes produced classical interferon (Type I) in response to NDV infection and produced immune interferon (Type II) in response to PHA, PPD or histo-incompatible antigens. Lymphocytes having higher specific gravity and having a greater proliferative response to mitogens or antigens produced more interferon than lymphocytes having lower specific gravity. There was no difference between heavy and light small tonsillar lymphocytes in regard to their sensitivity to the protective effects of interferon. As for the interferon produced in association with a cellular immune response, the peak of interferon production tended to appear earlier than the peak of 3H-TdR incorporation. It is suggested that tonsillar lymphocytes play an important role in human host defense against virus infections.

Enrichment in spontaneous and complement dependent rosette forming cell populations using Ficoll-Hypaque gradient centrifugation

Peripheral blood human T (TL) and B (BL) lymphocytes were separated by continuous Ficoll-Hypaque (FH) gradients. BL were found at the 1050 density interfase (70.5% EAC rosettes) with no TL (0% EAC rosettes); while at the 1068 density interfase there was an enrichment of TL (68% E rosettes) with very few BL (8.5% EAC rosettes).

Studies on difference in cellular immune-response between the human tonsil and blood lymphocytes

Tonsillar and blood lymphocytes in a viable state were separated from tuberculin-sensitive tonsillectomized patients. The difference in the response to various cellular immunological stimulation between both lymphocyte groups was studied. Tonsillar lymphocytes without adherent cells could not respond well to PPD, while blood lymphocytes responded far better than tonsillar lymphocytes did to PPD when adherent cells were absent. PHA and PWM stimulated tonsillar and blood lymphocytes irrespective of the presence of adherent cells. However, in case of PWM stimulation, 3H-TdR incorporation was more remarkable in tonsillar lymphocytes than in blood lymphocytes. Furthermore, the lymphocytes which react to homologous cells also existed in the tonsils as in blood. These results suggest that there might be lymphocyte-subpopulations showing a difference of functional roles or of maturing-process between tonsil and blood lymphocytes.

Changes in the stimulatory capability of mouse small thymocytes to give a proliferation of allogenic spleen cells during differentiation

Our previous studies on surface antigenic properties of murine small thymocyte subpopulations raised the hypothesis that some of the least dense cells, which possibly were precursor T cells, differentiated into the most dense cells which have the properties of mature T cells. Thus, the stimulatory capacity of the least dense was compared with that of the most dense by one-way mixed leukocyte culture. A marked difference in capacity between both subpopulations was found, i.e., the capacity of the least dense was the strongest of all subclasses, whereas that of the most dense was the weakest. It was concluded from discussions on this difference that the finding supported the hypothesis.