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Natural cell-mediated immunity in the rabbit
K A Laybourn1, J C Hiserodt, J M Hunt
1Department of Pathology and Laboratory Medicine, University of Texas Health Science Center, Houston 77030.
Abstract:
Susceptibility and resistance to tumors represent the interplay of many factors. One factor felt to govern the development of tumors is natural killer and natural cytotoxic cellular activity. The constitutional resistance of rabbits to spontaneous tumor development raises questions regarding the activity of natural cell-mediated immunity in this species. We therefore examined the ability of rabbit spleen, lymph node, and peripheral blood lymphocytes to mediate natural killer cell (NK) and natural cytotoxic cell (NC) activity in vitro. Using classical approaches to the study of NK and NC activity, we found no evidence of these activities in leporine spleen, lymph node, and peripheral blood lymphocytes. Preincubation of these cells with IL-2 did not induce such activity. Antibody-dependent cell-mediated cytotoxic reactivity (ADCC), which is believed to be mediated by NK cells, was also undetectable in rabbit lymphocytes. As controls, lymphocytes from other species were capable of mediating NK, NC, and ADCC functions normally in these experiments. Finally, we were unable to identify a population of large granular lymphocytes, the cells believed to mediate NK activity in other animals. Therefore, we could not demonstrate in the rabbit either natural cell-mediated immunity or the population of cells usually associated with natural cell-mediated immunity. If such activity exists in rabbits, it is different from that seen in other animals. More likely, the basis for the natural resistance of rabbits to tumor development must be sought elsewhere.
Insights
Rabbits show natural resistance to tumors, but lack natural killer (NK) and natural cytotoxic (NC) cell activity. Researchers found no evidence of these immune functions in rabbit lymphocytes, suggesting tumor resistance may stem from other mechanisms.
Area of Science:
- Immunology
- Comparative Oncology
- Cellular Biology
Background:
- Tumor development is influenced by various factors, including natural cell-mediated immunity.
- Rabbits exhibit inherent resistance to spontaneous tumor formation.
- The role of natural killer (NK) and natural cytotoxic (NC) cell activity in this resistance is unclear.
Purpose of the Study:
- To investigate the presence and activity of NK and NC cells in rabbits.
- To determine if rabbit lymphocytes possess natural cell-mediated immunity.
- To explore the cellular basis of rabbit resistance to tumors.
Main Methods:
- In vitro assessment of rabbit spleen, lymph node, and peripheral blood lymphocytes for NK and NC activity.
- Testing the effects of interleukin-2 (IL-2) preincubation on lymphocyte activity.
- Evaluation of antibody-dependent cell-mediated cytotoxicity (ADCC) in rabbit lymphocytes.
- Morphological examination for large granular lymphocytes.
Main Results:
- No detectable NK, NC, or ADCC activity was found in rabbit lymphocytes.
- IL-2 preincubation did not induce NK or NC activity.
- Lymphocytes from control species demonstrated normal NK, NC, and ADCC functions.
- The characteristic large granular lymphocytes associated with NK activity were not identified in rabbits.
Conclusions:
- Rabbit lymphocytes do not exhibit NK, NC, or ADCC activity comparable to other species.
- The natural resistance of rabbits to tumors is unlikely to be mediated by classical NK/NC cell-dependent mechanisms.
- Alternative pathways or factors must be responsible for the tumor resistance observed in rabbits.