### CD84 Gene Overview

**Gene Symbol**: CD84  
**Chromosomal Location**: Located on chromosome 1 (1q23.3).  
**Gene Type**: Protein-coding gene.

The **CD84** gene encodes a homophilic adhesion molecule and is part of the signaling lymphocyte activation molecule (SLAM) family. This gene plays a significant role in immune responses by modulating the activation and differentiation of various immune cells, including T-cells, B-cells, and natural killer (NK) cells. It is particularly involved in regulating both innate and adaptive immune responses through intercellular interactions.

### 1. Associated Genes
The CD84 gene is often associated with the following genes:

- **SLAMF1** (signaling lymphocyte activation molecule family member 1): Part of the same family, influencing immune cell interactions.
- **SH2D1A** (SH2 domain containing 1A): An adapter protein that interacts with SLAM family receptors to modulate immune responses.
- **SH2D1B** (SH2 domain containing 1B): Similar function to SH2D1A, involved in signaling pathways.
- **IRF8** (interferon regulatory factor 8): A transcription factor for immune system regulation, whose stability is influenced by CD84.
- **FES** (FES proto-oncogene): Involved in the signaling pathways related to immune responses.
- **PTPN6** (protein tyrosine phosphatase, non-receptor type 6): Also known as SHP-1, involved in immune regulation.

### 2. Aging or Age-Related Diseases Associations
While direct associations of CD84 with aging or age-related diseases may not be extensively characterized, there are several indirect implications:

- **Immune senescence**: The functionality of immune cells declines with age, affecting T-cell and B-cell interactions in germinal centers where CD84 is significant. Changes in signaling through CD84 may contribute to reduced immune responses in older adults.
- **Autoimmunity**: Given CD84's role in B-cell tolerance and the prevention of autoimmunity, dysregulation or mutation in this gene could contribute to age-related autoimmune diseases.
- **Cancer and CD84**: Altered CD84 expression may also influence the immunological environment in tumors, which could be more prevalent or altered in older populations.

### 3. Drug and Drug Classes Interactions
Currently, there are no specific drugs directly targeting CD84. However, it is implicated in several immune modulation therapies. Possible classes include:

- **Immunomodulators**: Agents that can enhance or inhibit immune responses might interact indirectly with pathways involving CD84, such as treatments for autoimmune diseases or cancer immunotherapy.
- **Cytokine therapy**: Drugs affecting tumor necrosis factor (TNF) or interleukins may have downstream effects on CD84 pathways.

### 4. Pathways and Biological Processes
CD84 is known to be involved in various biological processes, including:

- **Immune response**: Modulates signaling pathways in immune cells (T-cells, B-cells, NK cells).
- **Cell adhesion**: Homophilic interactions with itself contribute to the adhesion of immune cells.
- **Cytokine production**: Enhances secretion of various cytokines, including interferon-gamma (IFNG), following cell-cell interactions.
- **Proliferation of immune cells**: Supports the proliferative responses of T-cells upon activation.
- **Germinal center formation**: Critical for optimal T follicular helper function and sustaining B-cell responses.
- **Cytokine signaling**: In macrophages, influences LPS-induced cytokine production and MAPK/NF-kB signaling pathways.
- **Macroautophagy**: Positively regulates macroautophagy processes in primary dendritic cells through stabilization of IRF8.

Overall, the CD84 gene plays a crucial role in mediating immune responses and is integral to intercellular signaling in various immune cells, making it an important hub for research in immunology, particularly in the context of diseases and conditions associated with aging.