Antibody binds soluble antigen.
Each T lymphocyte is classified by the expression of the T cell co-receptor molecules, CD4 or CD8. Each antigen receptor complex communicates with a group of signaling molecules that alert the cell when the receptor binds antigen. These signaling molecules transduce signals by a tyrosine phosphorylation cascade that results in changes in gene expression, such as upregulation of cytokine genes. Binds the T cell coreceptor, CD8 2. Expressed on all cell types 3.