TABLE 11-2 PROPERTIES OF THYMUS-DEPENDENT AND THYMUS-INDEPENDENT ANTIGENS Tl antigens Property TD antigens Type 1 Type 2 Chemical nature Soluble protein Bacterial cell-wall Polymeric protein antigens; components (e.g.,LPS) capsular polysaccharides Humoral response Isotype switching Yes Limited Affinity maturation Yes o No Immunologic memory Yes No No Polyclonal activation No Yes(high doses) No TABLE 11-7 COMPARISON OF NAIVE AND MEMORY B CELLS Propertics Naive B cell Memory B cell Membrane markers Immunoglobulin IgM,IgD IgM,IgD(?),IgG,IgA,IgE Complement receptor Low High Anatomic location Spleen Bone marrow,lymph node,spleen Life span Short-lived May be long-lived Recirculation Yes Yes Receptor affinity Lower average affinity Higher average affinity due to affinity maturation' Adhesion molecules Low ICAM-1 High ICAM-I "Affinity maturation results from somatic mutation during proliferation of centroblasts and subsequent antigen selection of centrocytes bearing high-affinity mlg