Active Hematopoietic Hubs in Drosophila Adults Generate Hemocytes and Contribute to Immune Response

Summary

Blood cell development in Drosophila shares significant similarities with vertebrate. The conservation ranges from biphasic mode of hematopoiesis to signaling molecules crucial for progenitor cell formation, maintenance, and differentiation. Primitive hematopoiesis in Drosophila ensues in embryonic head mesoderm, whereas definitive hematopoiesis happens in larval hematopoietic organ, the lymph gland. This organ, with the onset of pupation, ruptures to release hemocytes into circulation. It is believed that the adult lacks a hematopoietic organ and survives on the contribution of both embryonic and larval hematopoiesis. However, our studies revealed a surge of blood cell development in the dorsal abdominal hemocyte clusters of adult fly. These active hematopoietic hubs are capable of blood cell specification and can respond to bacterial challenges. The presence of progenitors and differentiated hemocytes embedded in a functional network of Laminin A and Pericardin within this hematopoietic hub projects it as a simple version of the vertebrate bone marrow.

Graphical Abstract

Highlights

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  An active hematopoietic hub exists in the abdomen of adult Drosophila

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  Progenitors within the hub can give rise to plasmatocytes and crystal cells

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  Resident plasmatocytes show immune responses and proliferate upon infection

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  Progenitors residing in the hub originate from the posterior lobes of lymph gland

Abstract

Definitive hematopoiesis in Drosophila was thought to occur only in the larval hematopoietic organ, which ruptures upon pupation. Ghosh et al. now demonstrate the presence of active hematopoietic sites in the abdomen of adult flies, which can give rise to new blood cells and can respond to immune challenges.