Erythrophagocytosis in circulating blood of loggerhead turtlesCaretta caretta: The pitting of Heinz bodies

Abstract

In humans red blood cells live on average of 120 days. Senescent erythrocytes are removed from circulation by macrophages; this process, called erythrophagocytosis (EPC), takes place mainly in the liver but also in the bone marrow. We studied this process in loggerhead turtles Caretta caretta, inhabiting the Mediterranean Sea. Leukocytes of reptiles include heterophils, eosinophils, lymphocytes, basophils, thrombocytes, monocytes, and of these heterophils and monocytes represent the main phagocytic cells. The aim of this study was to investigate the blood of C. caretta specimens and to observe, in the blood smears, heterophils phagocytizing erythrocytes. The phagocytizing cells were also identified by cytochemical reactions. Furthermore some examples of tear-shaped erythrocytes (dacrocytes) were observed. A mechanism presuming a causative link between erythrophagocytosis and teardrop-erythrocyte detection have been proposed to explain this seemingly general pattern of all specimens both wild and housed.

Letter to the Editor: Heinz bodies and erythrophagocytosis in the peripheral blood of loggerhead sea turtles

“…Finally, we question the interpretation of some of the cytochemical staining results of leukocytes as shown in the second paper (Fig. , Ruggiero et al, ). Heterophils appear to be negative rather than positive for peroxidase, and the CAE‐positive cell is likely an eosinophil, rather than a heterophil.…”

“…A second paper from this laboratory, Ruggiero et al () describes erythrophagocytosis by heterophils in the peripheral blood. Erythrophagocytosis is identified by intracytoplasmic whole or fragmented erythrocytes, sometimes also with variable amounts of greenish‐basophilic material suggestive of hemosiderin (Fig.…”

Letter to the editor: Theileria in loggerhead sea turtles Caretta caretta

“…Figure 4 a,b by Di Santi et al are reported to show heterophils phagocytizing parasitized erythrocytes. The morphologic description of erythrophagia in loggerhead turtles has been recently addressed (Stacy and Harvey 2015) in response to another publication by this laboratory (Ruggiero et al 2013). As stated previously, we disagree that erythrophagia is present in the images in which it is described.…”

Ultrastructure of Theileria-infected blood cells of loggerhead turtles

“…The capacity of this parasite to cause host cell transformation is unique among eukaryotic pathogens. In fact, as textually reported by Marsolier et al (2015), BTheileria is the only Genus that transforms its mammalian host cells.^In addition, the detection of active erythrophagocytosis in circulating blood is another recognized phenomenon in response to parasitization (Jaensch and Raidal 2006;Ruggiero et al 2014). Moreover, Theileria-infected cells were detected and photographed in ideal areas in the center of microscopic fields and not in thick-smeared regions.…”