Makio Iwashima, PhD

Associate Professor

Ph.D., Stanford University

Major Research Interests: Cell biology of T cell subsets

T lymphocytes play critical roles in immune responses against infections and tumors. The majority of T lymphocytes are called effector cells. They function in the first line of host defense by producing cytokines, inducing antibody formation, and directly killing infected or transformed cells. Many effector T cells die after completing their responses against antigens, but a group of effector cells remain in the periphery and survive for a long period of time as "memory" T cells. These memory T cells play a critical role in the maintenance of immunological memory and are key for effective vaccination. The loss of memory T cells contributes to the impairment of the immune responses in aged populations.

Another small group of T cells, called regulatory T cells, plays a significant role in suppressing unwanted immune responses against self-antigens. Decreased numbers of regulatory T cells, or impairment of their function, leads to autoimmune disorders such as Type I diabetes or inflammatory bowel disease. Conversely, increased numbers of regulatory T cells may contribute to chronic infectious diseases or growth of tumors.

Our main research interest is to elucidate the molecular and cellular characteristics of memory and regulatory T cells. The main questions that we address are: 
(1) How do memory T cells survive in vivo for a long time? 
(2) How is the balance between regulatory and effector T cells controlled?
(3) How do regulatory T cells control immune responses?

We have developed procedures to isolate and expand these minor fractions of T cells and we are examining them in detail by proteomic, genomic, and imaging analysis. Successful completion of these studies will potentially lead to treatment for autoimmune disorders, enhancement of immune response against tumors, and development of vaccine effective for immunocompromised individuals