T Cells (Ch 10)
A. Characteristics of lymphocytes (B and T)
1. origin of cells
a. T cells = thymus
b. B cells = bursa equivalent tissue
2. features of lymphocytes
a. represents about 20% of circulating WBC
b. high N/C ratio
c. B and T cells appear similar microscopically
d. distinguished by cell surface markers and response to mitogens
B. T cells
1. represents about 75% of circulating lymphocytes
2. cell surface markers
3. TCR = T cell antigen receptor
4. T cell subsets
a. CD4+ cells = T helper
b. CD8+ cells = cytotoxic cells (Tc or CTL)
c. suppressor cells
d. memory cells
C. Thymic selection (positive, negative)
D. Th cell activation
E. Superantigens