 The bare lymphocyte syndrome, type II (BLS II) is a rare recessive genetic condition in which a group of genes called major histocompatibility complex class II (MHC class II) are not expressed.The result is that the immune system is severely compromised and cannot effectively fight infection.Clinically, this is similar to severe combined immunodeficiency (SCID), in which lymphocyte precursor cells are improperly formed.