T cell-independent activation B cell

antigens activate b cells without t cell known t cell-independent (ti) antigens , include foreign polysaccharides , unmethylated cpg dna. named such because able induce humoral response in organisms lack t cells. b cell response these antigens rapid, though antibodies generated tend have lower affinity , less functionally versatile generated t cell-dependent activation.

as td antigens, b cells activated ti antigens need additional signals complete activation, instead of receiving them t cells, provided either recognition , binding of common microbial constituent toll-like receptors (tlrs) or extensive crosslinking of bcrs repeated epitopes on bacterial cell. b cells activated ti antigens go on proliferate outside lymphoid follicles still in slos (gcs not form), possibly undergo immunoglobulin class switching, , differentiate short-lived plasmablasts produce early, weak antibodies of class igm, populations of long-lived plasma cells.