Mechanisms of TIndependent Antibody Responses

The most important TI antigens are polysaccharides, gly-colipids, and nucleic acids, all of which induce specific antibody production in T cell-deficient animals. These antigens cannot be processed and presented in association with MHC molecules, and therefore they cannot be recognized by CD4+ helper T cells. Most TI antigens are multivalent, being composed of repeated identical anti-genic epitopes. Such multivalent antigens may induce maximal cross-linking of the BCR complex on specific B cells, leading to activation without a requirement for cognate T cell help. In addition, many polysaccharides activate the complement system by the alternative pathway, generating C3d, which binds to the antigen and is recognized by CR2, thus augmenting B cell activation (see Fig. 11-5 and Chapter 7). Membrane proteins at a high density on a microbial surface may be functionally multivalent and may function in a T-independent as well as in a T-dependent manner. As mentioned earlier, TI responses may also be facilitated by additional signals derived from microbial products that activate TLRs on B cells.

TABLE 11-2 Properties of Thymus-Dependent and Thymus-Independent Antigens

Was this article helpful?

0 0
How To Bolster Your Immune System

How To Bolster Your Immune System

All Natural Immune Boosters Proven To Fight Infection, Disease And More. Discover A Natural, Safe Effective Way To Boost Your Immune System Using Ingredients From Your Kitchen Cupboard. The only common sense, no holds barred guide to hit the market today no gimmicks, no pills, just old fashioned common sense remedies to cure colds, influenza, viral infections and more.

Get My Free Audio Book


Post a comment