Splenic Pigmented Macrophage Aggregates in Barbel (Barbus peloponnesius, Valenciennes, 1844) from River Bregalnica — Influences of Age, Sex and Season on a Pollution Biomarker

Abstract

Macrophages are involved in innate and acquired immune responses, being key players in immunotoxicology. Changes in the quantities of pigmented macrophage aggregates (PMQ) in fish are often used as biomarkers of pollution. Most studies offer only qualitative data on PMQ changes, and effects of age, sex and season are poorly known. We present a stereological study of the relative and total volumes of PMQ in the barbel, Barbus peloponnesius spleen. Our focus is to disclose influences of age, sex and season on PMQ, and check if the there is any positive association with aging. The females had a significantly higher spleen and body weights and length. PMQ loaded with lipofuscin/ceroid and hemosiderin were dispersed throughout both spleen pulps. Seasons impacted on PMQ, despite no too markedly. Differences existed between sexes, with males having significantly higher relative volumes of PMQ: the total volumes had similar tendencies. The volumes of PMQ were positively associated with age. The new data reinforce the importance of studying influences of both intrinsic and extrinsic factors that model the quantities of PMQ so to better interpret their changes seen in biomonitoring works