These cell surface receptors may be Broadly specific (eg, pattern-recognition receptors such as Toll-like, mannose, and scavenger receptors on dendritic and other cells) Highly specific (antibodies expressed on B cells or T-cell receptors expressed on T cells) Broadly specific receptors recognize common microbial pathogen-associated molecular patterns such as gram-negative lipopolysaccharide, gram-positive peptidoglycans, bacterial flagellin, unmethylated cytosine-guanosine dinucleotides (CpG motifs), and viral double-stranded RNA.