In most populations, the antithetical LW antigens, LWa and LWb are present as very high and very low frequency, respectively.
[2] The LW glycoprotein has recently been renamed ICAM-4 due to its similarity to intercellular adhesion molecule, although exactly which integrins bind to ICAM-4 is subject to controversy.
[1][2][3] Despite the functional aspects of ICAM-4, its apparent absence in LW(a-b-) and Rhnull phenotypes does not appear to lead to any obvious pathological effects.
[1][2] Auto anti-LW is not uncommon as an autoantibody but usually presents with transient suppression of the LW antigen in genetically LW+ individuals, and so appears to be an alloantibody.
True alloanti-LW is a very rare occurrence, with only two known examples of alloanti-LWab, produced by patients with an LW(a-b-) phenotype.