Recent insights in the development and functions of insect hemocytes

Donna Huber on September 15, 2025

Figure 1. Cellular defense responses, humoral effector molecules and regulators of hemocyte functions in insects. In the center of the figure is a stylized image of an insect hemocyte. The arrow to the left points to the four major cellular defenses that are mediated by hemocytes. The arrow to the right points to five of the most important humoral effector molecules hemocytes produce. The upper arrow points to key receptors with functions in regulating hemocyte-mediated cellular defenses, while the lower arrow points to cytokines that regulate hemocyte functions or communication between hemocytes and other tissues. Small case statements below some headings provide brief explanations of terms while additional details are presented in the main text.
Figure 1. Cellular defense responses, humoral effector molecules and regulators of hemocyte functions in insects.

Hemocytes mediate defense responses that are collectively referred to as cellular immunity. Here I highlight recent progress in the study of hemocyte ontogeny and function. Studies conducted primarily in D. melanogaster, mosquitoes and Lepidoptera identify a number of transcription factors and signaling pathways that regulate hemocyte differentiation and proliferation. Recent single cell RNA sequencing studies identify genes that distinguish transitional states in different hemocyte populations and changes that occur during immune responses. Several new studies expand understanding of the functions of sessile hemocytes. Recent results also enhance understanding of the signaling pathways that regulate hemocyte functions.

Michael R Strand. Curr Opin Insect Sci. 2025 Sep 15:101434. doi: 10.1016/j.cois.2025.101434.