Ultrastructure of Cytotoxic Cells in Frogs |
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| Authors: | C. T. Smith M. Ghoneum and E. L. Cooper |
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| Affiliation: | Department of Anatomy, School of Medicine, University of California, Los Angeles, CA 90024;Charles R. Drew Postgraduate Medical School, Los Angeles, California 90059, U.S.A. |
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| Abstract: | Our previous work gave evidence that leopard frogs ( Rana pipiens ) possess inducible killer (IK) cells (CTL-like) and spontaneous killer (SK) cells (NK-like) that can destroy allogeneic RBC. To further characterize these cytotoxic cells we have examined their ultrastructural morphology and effector cell-target cell membrane contacts. We also studied the sensitivity of these two effector cells to low temperature (4°C). Our results showed that SK effector cells are lymphocytes (10 μm) which contain numerous vacuoles and osmiophilic granules, while IK effectors are another lymphocyte population (up to 12 μm) with a small amount of cytoplasm and few mitochondria. Both IK- and SK-mediated lytic responses were suppressed significantly by low temperature. These observations allow us to propose that frog SK and IK cells may be homologous to mammalian NK and CTL. |
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