Immunoglobulin superfamily

Immunoglobulins are circulating plasma proteins manufactured mainly by B-cells (plasma cells). Proteins that have an immunoglobulin like domain in them (two $\beta$ pleated sheets joined by a disulfide bond) are classed as being part of the immunoglobulin superfamily. The endothelium expresses members of the immunoglobulin superfamily to act as receptors for integrins expressed on leucocytes.

The five members of the immunoglobulin superfamily are ICAM-1/2/3, VCAM-1 and PECAM-1. The two most important members appear to be ICAM-1 and VCAM-1.