Vol. 44, No. 4, 2000 previous next

THE SPONTANEOUS REGRESSION OF CONGENITAL MELANOMAS IN PIGS: THE ULTRASTRUCTURE AND ROLE OF MACROPHAGES, MAST CELLS AND PLASMA CELLS

Zibrín, M., Levkut, M., Pivko, J.*, Tomajková, E., Komorová, T., Kolodzieyski, L.

University of Veterinary Medicine
Komenského 73
041 81 Košice
The Slovak Republic		 * Research Institute of Animal Production
Hlohovská 2
942 92 Nitra
The Slovak Republic
This paper was originally presented at the international symposium organized on the occasion of the 75th anniversary of the birth of Prof. Peter Popesko, M.V.D., D.Sc., held at The University of Veterinary Medicine, Košice on 2 June 2000

Summary

Transmission electron microscopy of cutaneous congenital melanomas in 12 piglets revealed two distinct types of macrophages which differed according to their morphology and function. Melanophages are specialized macrophages that engulf, store, and degrade melanin pigment granules. The macrophages of the second type, formerly known as epithelioid cells, produce specific proteins and remove collagen fibres. Both types of macrophages participated in the removal of neoplastic material in the regressive stages of congenital melanomas. The role of macrophages in the killing of neoplastic melanoma cells is briefly discussed. We conclude that not only lymphocytes (NK and K cells - natural killers and killer cells) but also both types of macrophages play an important role in the regression of melanomas. Plasma cells - and a few mast cells - were also occasionally observed in regressive melanomas in pigs. The precise role of these cells in the regression of congenital pig melanomas remains to be elucidated.

Key words: congenital melanoma; spontaneous regression; macrophages; plasma cells; mast cells; ultrastructure; pigs

References

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Folia Veterinaria / 2000