Phagocytes from both vertebrate and invertebrate species use "coiling" phagocytosis

Coiling phagocytosis has been observed previously only by chance, and there has been no systematic investigation of this uptake mechanism. Therefore, a comparative electron microscopical study was performed. Different human and murine cell populations, phagocytes from various vertebrate and invertebrate species, and predatory amoebae were incubated with Borrelia burgdorferi, one of the microbes known to induce coiling phagocytosis, to study the uptake mechanisms used. In this model, coiling phagocytosis was observed with both vertebrate and invertebrate species but not with amoebae. With cells from humans and mice, this uptake mechanism was restricted to phagocytic cells of myeloid origin. The coiled membrane gaps did not give rise to phagosomes; instead, membrane fusion was followed by membrane dissipation. Thus, coiling of B. burgdorferi apparently is an alternative uptake mechanism used by metazoan phagocytes, involving special membrane processing. However, coiling phagocytosis may show different features with different microbes.