Greater Proliferative Response Research Articles

Normal and Sublethally Irradiated Stem and Granulocyte Progenitor Cell Regeneration in an in Vivo Culture System: The Cellular Response to Humoral Factors Released through the Action of Cyclophosphamide

The in vivo diffusion chamber (DC) method of marrow culture was used to determine if the injection of host mice with cyclophosphamide (CY) caused, through its cytoxic action, the release of a humoral factor(s) capable of initiating stem cell (CFU-s) and granulocyte-macrophage progenitor cell (CFU-c) proliferation. Host mice were injected with CY 1-4 days prior to 800 rad of /sup 60/Co WBI and implantation of DCs containing normal or 400 rad sublethally irradiated (SLI) marrow cells. The greatest proliferative response within CFU-s and CFU-c populations occurred in those mice injected with CY 3 days prior to implant. The marked CFU-s and CFU-c regeneration was initiated during the initial 24 hr of culture in both normal and SLI marrow cells. Thereafter growth rates were approximately the same. SLI marrow, however, showed a greater response to the humoral effects of CY injection than did normal marrow. These data provided evidence that CY induced the release of a diffusible factor(s) capable of accelerating regeneration of normal and sublethally irradiated CFU-s and CFU-c, the magnitude of which was dependent upon the time elapsed between CY injected and implantation of DCs. The marked proliferative response of the SLI stem and progenitor cells to the humoralmore » stimulation may be indicative of the heterogeneity of both CFU-s and CFU-c populations surviving sublethal radiation exposure. The target cells may have possessed a differential sensitivity to the factor(s) initiating cell proliferation.« less

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.

PROLIFERATIVE RESPONSES OF CYCLOSTOMES TO STIMULATION WITH ANTIGEN IN ADJUVANT

Studies of the proliferative responses of certain organs and tissues following injection of BSA and Freund's adjuvant in hagfishes and lamprey have been made. Using 32P incorporation into DNA as an indicator, no significant proliferation was observed in blood, intestinal mucosa, intestinal epithelium or gills of the hagfish. In the lamprey, 32P incorporation into DNA revealed increased proliferation of gills, blood, protovertebral arch hematopoietic tissue and intestine. Responses of gills and blood cells were on statistically significant levels, whereas those of intestine and protovertebral arch did not reach statistical significance. By autoradiography evidence of greater proliferative responses in the blast type cells in the blood of the stimulated than the unstimulated hagfishes has been presented. In the lamprey, autoradiography revealed increased proliferative responses of the blast type cells, lymphocytes and polymorphonuclear cells of the protovertebral arch following stimulation with antigen in adjuvant.