# Research Advances in the Immunomodulatory Functions of CD100/SEMA4D and Their Roles in Viral Infectious Diseases

## TL;DR

This review explores CD100/SEMA4D's role in immune regulation and its impact on viral diseases, summarizing its molecular features and clinical potential.

## Contribution

The paper provides a systematic review of CD100's immunomodulatory functions and its relevance in viral infections.

## Key findings

- CD100 is expressed on various immune cells and exists in both membrane-bound and soluble forms.
- It plays a critical role in regulating immune responses during viral infections.
- Its expression is modulated by immune cell activation states.

## Abstract

CD100/SEMA4D, a member of the Semaphorin family, is a transmembrane glycoprotein that regulates neurogenesis, immune modulation, and angiogenesis, with its immunoregulatory roles having attracted considerable attention. It is dynamically expressed on the surface of diverse immune cells—including T cells, B cells, dendritic cells (DCs), and natural killer (NK) cells—with expression levels modulated by cellular activation states. CD100 exists in two functional forms: membrane-bound CD100 (mCD100) and soluble CD100 (sCD100) generated via proteolytic cleavage. Recent studies have highlighted its critical involvement in viral infectious diseases. This review systematically summarizes the molecular characteristics, expression patterns, and regulatory functions of CD100 on different immune cells, and discusses its role in viral infectious diseases and its clinical application potential.