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SummaryAntibody production by normal mouse spleen cells in vitro requires the presence of both adherent and nonadherent cell populations. The data presented here demonstrate that by the addition of alpha-tocopherol (vitamin E) to the medium nonadherent spleen cells can be stimulated to respond to sheep red blood cells in the relative absence of adherent cells. In addition, alpha-tocopherol will enhance in vitro immune responses by populations of spleen cells containing both adherent and nonadherent cells.

SummaryThe ATPase activity in spleens of mice immunized with sheep erythrocytes was examined. A maximal increase in ATPase activity was found at the time when peak numbers of specific antibody forming cells were evident in the mouse spleen, 4–5 days after immunization. A relationship was observed between antigen dose and the peak response of both antibody PFCs and ATPase activity. The Mg2+-ATPase activity was specifically enhanced, while no increase in Na+K+-ATPase activity was demonstrable. These results suggest that a relationship exists between Mg2+-ATPase activity and antibody formation in mouse spleens.

SummaryUnder certain conditions C3H mice implanted with lymphosarcoma 6-C3HED were protected either by injection of ZBC spleen tissue alone or by A-methopterin treatment alone. A more successful treatment consisted of a single subcutaneous injection of ZBC spleen tissue with daily doses of A-methopterin. Mice which had received tumor implantations 24, 48 or 96 hours preceding therapy were treated with this combination. Some were not protected, but in others tumors either failed to become palpable, or having become palpable appeared to have regressed completely.

ConclusionThe experiments discussed above serve to illustrate the fact that decreases in numbers of nodules can occur following irradiation of mice either a) to the whole body, or b) with the tail shielded. The phenomenon is as yet unexplained, and there is little evidence to indicate the nature of concomitant events at the cellular level.These findings might conceivably be related to the “abortive rise” in numbers of cells in bone marrow and peripheral blood, seen following whole-body irradiation of mammals(5). The abortive rise is thought to be an expression of cellular radiation damage. As such, it might be related to the decrease found with endogenous nodules, but not to that found with tail shielding, in which case the nodules arise principally from cells in the shielded tail.A second effect, which suggests itself as being relevant because of its resemblance to the slow growth found in endogenous nodules, is the “small colony formation” reported by Sinclair(6) for cultures of heavily irradiated mamma...

SummaryA new modification of the organ culture technic has been described utilizing glass beakers, Teflon® rings and lens paper. It is relatively simple and easily adapted to large-scale use. Mouse spleen fragments cultivated by this method demonstrated early loss of follicular pattern, degeneration of lymphocytes and proliferation of reticulum cells. After 2 weeks of cultivation new lymphoid follicles formed and by 4 weeks follicular pattern was well established, with appearance of lymphocytes in all stages of development. In addition, plasma cells, megakaryocytes and reticulum cells were present and at the periphery, which was partially surrounded by a fibrous capsule, there were present numerous macrophages containing hemoglobin pigment.

SummaryThe intravenous injection of PWM to mice produced in vivo changes in the spleen similar to those produced by intravenous injection of PHA. These changes were a marked increase in the weight of the spleen, along with an increase in the number of nucleated cells, lymphoblasts, and mitotic figures. In addition, PWM also produced a marked increase in the total number of plasma cells. However, these cells did not appear in the peripheral blood, and the effect of PWM on it was limited to a transient leukopenia.The technical assistance of Mrs. Barbara Kartzinel is gratefully acknowledged.

Summary and conclusions1. Continuing previous studies, employing improved bio-assay methods, the protective effect of cell-free saline extracts made from spleens of normal mice against X-ray-induced mortality in this species has been demonstrated. 2. Extracts made from the spleens of donor animals exposed to an X-ray dose which killed 55% of the donor animals in 14 days failed to show a protective effect, which was in agreement with previous observations. 3. A certain amount of parallelism between the protective effect of various extracts made from normal mouse spleens and the failure to protect of those made from irradiated mouse spleens was found in studies of the total protein and NPN content of such extracts. 4. It appears that within a wide range of concentration of total protein and NPN content such protection can be achieved. 5. However, reduction of average content of total protein and NPN below one-half of lowest average value for normal spleens, ascertained in samples made from spleens of irradi...

SummaryFollowing experiments which suggested that apparent stimulation of mouse spleen cells by fetal calf serum (FCS) was masking specific blastogenic effects in the mixed leukocyte culture (MLC), cultures of CBA and BALB/c spleen cells were set up in RPMI-1640 medium, containing FCS at 5, 4, 3, 2, 1 and 0%. On termininating the cultures on day 4, the ratio of 3H-thymidine incorporation between the mixed and the separate cultures was found to be considerably higher in absence of FCS than in the presence of FCS at any of the concentrations indicated. A series of timed cultures, without any FCS, showed a ratio between the incorporation of 3H-thymidine in the mixed cultures and the sum of incorporation in cultures of separate cells which reached a maximum level of 11-15, on day 5 or 6. In tests with cells of other sources, it was found that thymus cells could serve as a source of allogeneic antigen, but could not incorporate thymidine, and that bone marrow cells could be stimulated, but to a lower degree th...

SummaryThe kinetics of the hemolytic antibody response in mice to a single injection of sheep erythrocytes were determined by quantitating the number of hemolytic foci which appeared in an agar-erythrocyte over-lay on thin sections of mouse spleen. After immunization, the number of foci rose to a peak and then declined gradually to levels which persisted through 113 days. At 210 days after immunization, foci activity had merged with control levels. On the other hand, the plaque-forming cell method of Jerne showed an increase in the number of plaque-forming cells until a peak was reached with a subsequent rapid decline to control levels 70-80 days after immunization. It is concluded that the frozen section technique is a sensitive method for the discrimination and enumeration of cells containing specific antibody in tissues.

SummaryThe in vitro response to PHA by mouse spleen cells is diminished by treatment of animals with complete Freund adjuvant (0.25 ml ip) or azocasein (daily sc injection of 0.3 ml of 10% solution). The altered response appears, in part, due to prior in vivo activation of PHA-responsive cells by azocasein or CFA. Azocasein has some mitogenic activity when incubated with normal cells in vitro.

SummaryAn in vitro system for quantitatively measuring hemolysin production by mouse spleen cells is described. The synthesis of hemolysin was shown to be de novo and the rate of appearance was linear with respect to culture time. Known immunosuppressive chemicals were tested using this system and were found to be effective at inhibiting antibody production whereas nonimmunosuppressive drugs were noneffective. These findings suggested that this system would be suitable for rapidly screening chemicals for immunosuppressive activity and may be of aid in determining their mode of action at a cellular level.

SummaryRat thymus cells were used as target cells in Jerne agar plaque technique to detect and enumerate antibody-forming cells of mouse stimulated with this antigen. 51Cr-labeled rat thymus cells were also used in these experiments to carry out plaque assay autoradiographically. The techniques demonstrated complement-dependent cytolytic plaques caused by antibodies released from immune mouse spleen cells and could be used to investigate kinetics of antibody-forming cells.