ICOS deficiency

The ICOS-deficient patients have recurrent bacterial infections of the respiratory and digestive tracts characteristic of humoral immunodeficiency. They lack other complicating features of CVID such as splenomegaly, autoimmune phenomena, or sarcoid-like granulomas and do not present with clinical signs of overt T cell immunodeficiency. ICOS deficient patients develop an adult-onset immunodeficiency characterised by low number of B cells, lack of memory cells and low serum Ig.