1. Immunology Chapter 3, Lecture 2 Richard L. Myers, Ph.D. Department of Biology Southwest Missouri State Temple Hall 227 Telephone: 417-836-5307 Email: rlm967f@mail.smsu.edu

2. Lymphocytes Lymphocytes are the most important cells of the immune system Other white cells play accessory roles –engulfing and destroying microorganisms –presenting antigens –secreting cytokines

3. Lymphoid cells Found in blood, lymph, tissue and organs Broadly subdivided into B, T and null cells Virgin, naïve or unprimed cells are resting Antigen causes them to enter the cell cycle These cells enlarge into lymphoblasts Become either effector or memory cells Different groups possess a cluster of differentiation or CD

4. Lymphocyte

5. Isolation of mononuclear cells

9. Lymphoblast proliferation Upon antigen interaction, lymphoblasts differentiate into: –effector cells to eliminate antigen B cells (plasma cells) and T C and T H cells –memory cells responsible for life-long immunity

10. B lymphocyte Possess sIg, the receptor (BCR) for antigen An important B cell marker is CD45 (B220) Most B cells express class II MHC Antigen presentation causes clonal selection Differentiation process produces plasma and memory cells Plasma cell secretes a particular class of antibody

11. Sir F. Macfarlane Burnet Burnet was Director of the Walter and Eliza Hall Institute of Medical Research, Melbourne 1944-66 and in 1960 was awarded the Nobel Prize for physiology or medicine with Medawar.

15. T lymphocyte Maturation occurs in the thymus T cells possess receptors for antigen (TCR) TCR must see antigen associated with an MHC gene product Only sees antigen displayed on self cells Thy-1 is the earliest marker of a T cell Other important markers are CD4 and CD8

16. T lymphocytes (continued) CD4 T cells recognize antigen associated with class II MHC molecules CD8 T cells recognize antigen associated with class I MHC molecules CD4 T cells function as T helper cells CD8 T cells function as T cytotoxic cells A suppressor T cell has been proposed

17. Null cells Do not have T or B cell surface molecules No antigen binding receptors Do not have immunologic memory or specificity Some are called natural killer cells (NK) Important in tumor immunity Some involved in ADCC

18. Assignment Continue reading Chapter 3, Cells and Organs of the Immune System Review questions 12 and 13 (pg 83)