Miller’s seminal studies on the role of thymus in immunity

Abstract

SummaryThe thymus is one of the two primary lymphoid organs. It is responsible for the provision of T lymphocytes to the entire body, and provides a unique microenvironment in which T cell precursors (thymocytes) undergo development, differentiation and clonal expansion. This review article summarizes the seminal work of the Australian scientist Francis Albert Pierre Miller concerning the description for the first time of the crucial role of the thymus for normal development of the immune system.

Malnutrition alters the rates of apoptosis in splenocytes and thymocyte subpopulations of rats

“…Glucocorticoids utilize the Bcl-2 modulated pathway of apoptosis. This pathway is also used when cells are deprived of sera or essential nutrients [9]. Knowledge of this pathway led to the supposition that the endogenously produced glucocorticoids, perhaps acting in synergy with nutritional deficiencies, would initiate this death pathway, causing accelerated death among cells with low levels of Bcl-2 expression [31].…”

“…Increased understanding of the organization of the immune system and the factors that regulate immune function have demonstrated a remarkable and close concordance between host nutritional status and immunity [3]. Because the thymus is responsible for the provision of T lymphocytes to the entire body and provides a unique microenvironment in which T cell precursors (thymocytes) undergo development, differentiation and clonal expansion [9], information regarding the physiology of the thymus is essential to understand more clearly the immunodeficiency seen in malnourished individuals [8].…”

“…The thymus is a primary lymphoid organ in which bone marrow-derived T cell precursors undergo differentiation, leading ultimately to the migration of positively selected thymocytes to peripheral lymphoid organs [9]. This process involves the sequential expression of various proteins and rearrangements of the T cell receptor (TCR) genes.…”

The Thymus: A Forgotten, But Very Important Organ

“…The overall size of the thymus in adults is much smaller than in children, whereas the amount of nonfunctional tissue is much higher. This is accompanied by the loss of the organized architecture and increased fat cell deposition in this organ [17]. There are several possible explanations for this involution, such as the scarcity of T-cell precursors from bone marrow, the effects of circulating hormones and cytokines, or the loss of thymic architecture with age [18].…”

“…The result of this activation is the secretion of antibodies and mitosis of T-cells, resulting in increasing quantities of T-cells recognizing the antigen. This is an immediate response to a pathogen [17]. When the pathogen is eliminated, the activated cells undergo apoptosis, and only a few survive as memory immune cells.…”