Immune Science

The Immune System

The immune system is the most complex and finely tuned internal ‘medicine-producing’ engine ever created. Much of its power lies in the T cell repertoire. We are born with millions of unique T cells known as clones which together comprise our T cell repertoire. These immune cells survey our tissues for cancer or infectious agents. When a T cell clone identifies a cancer antigen or a virus infected cell, the T cell is activated to become a potent immune medicine. Harnessing the power of the T cell repertoire is the next frontier in biotechnology and immunology.

Immune Science

The field of immune science seeks to produce T cells that can more effectively target cancer and other hard-to-treat diseases that can evade the normal immune system.

The Role of T Cells

T cells (also called T lymphocytes) are a major component of the adaptive immune system. Our bodies have many millions of different T cells. Each T cell will develop its own T cell receptor (TCR) that is specific for a particular antigen (tiny piece of pathogen or virus that is displayed on a cell’s surface). T cells constantly scan other cells for an antigen match. Their roles include directly killing infected host cells, activating other immune cells, and regulating the immune response.

The T Cell Repertoire

When activated, the T cell repertoire creates potent medicines. This happens every day as our bodies defend against disease-causing antigens. Harnessing this power requires a deep understanding of the codes that activate them, and that code is determined by the immune synapse.

Synapse photo 1 5x — T cell engaging an antigen presenting cell

The Immune Synapse

The immune synapse is the interaction between the T cell and the antigen presenting cell which dictates the activation of the T cell. In other words, the immune synapse is the immune code that tells a T cell to become toxic and to kill the infected tissue. Understanding the immune synapse is akin to understanding computer codes. Together, the peptide sequence and the T cell receptor (TCR) sequence are the key to the immune code, but the TCR-peptide interaction is transient and antigen presentation varies by the immune genetics of the individual, displayed in the context of an individual’s major histocompatibility complex (MHC) I and II.

The Role of MHCs

The major histocompatibility complex (MHC) is responsible for the coding of proteins that the immune system uses to identify cells and tissues in the body as “self” or “other”. MHC molecules "talk" to T cells that patrol the body for foreign invaders or dangerously mutated cells. The MHC acts as a window into our cells. It presents snippets of information (peptides) on the state of the cell – allowing the immune system to check for infection, cancer, and other maladies. Cells that do not pass the self/other test are eliminated.

MHC molecules comprise two individual parts that present short epitopes (short peptides) to cells of the immune system. There are two main classes of MHC molecule – Class I and Class II.

Class I MHC 

Found on all nucleated cells in the body and on platelets.
Interacts with CD8+ T cells, interacting directly with CD8 as a co-receptor. Presentation of intracellular epitopes allows T cells to check for intracellular bacteria, viral infection and cancerous mutations. MHC I present epitopes of 8-10 amino acids to T cells, and serve as a global “alarm” system for the cells in the body.

Class II MHC 

Typically found on antigen presenting cells (APC) such as macrophages, dendritic cells, and B lymphocytes. These MHC molecules interact with CD4 on CD4+ T helper cells.
Presentation functions as a specific line of communication between immune cells and the global immune system.
Presentation is a requirement for initiating and sustaining adaptive immune responses against foreign invaders such as fungi and extracellular bacteria.