Natural cell-mediated cytotoxicity in rats. III. Effects of immunopharmacologic treatments on natural reactivity and on reactivity augmented by polyinosinic-polycytidylic acid
✍ Scribed by J. Ronald Oehler; Ronald B. Herberman
- Publisher
- John Wiley and Sons
- Year
- 1978
- Tongue
- French
- Weight
- 804 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0020-7136
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Treatment of rats with high doses of hydrocortisone, X‐irradiation, or cyclophosphamide had a suppressive effect on natural cytotoxicity in vivo. However, when rats were given poly I:C ^3^ after any of these agents, the levels of NK activity were similar to those in normal rats which had been given poly I:C alone. To explain these findings, we have postulated that a population of pre‐NK cells, resistant to hydrocortisone, cyclophosphamide and X‐irradiation was induced by poly I:C to become cytotoxic NK cells. Treatment of rats with silica, in doses that had no effect on proliferative responses of host lymphocytes to Con A in vitro, sharply diminished NK activity. With this agent, the boosting effect of poly I:C, although still detectable, was diminished. Since there is little if any indication that NK cells are phagocytic, these data suggest that phagocytes may play a role in maintaining high levels of NK activity in vivo and, further, may be involved in the mechanism by which natural cytotoxicity is boosted by poly I:C. Adult thymectomized rats had easily detectable levels of natural reactivity and the response to poly I:C was unimpaired, indicating a lack of thymic dependence for boosting as well as for spontaneous levels of NK activity.