[Heterogeneity of epitopes of the CD4 molecule in a female patient with idiopathic pulmonary fibrosis].

Heterogeneity of the CD4 antigen epitopes has been occasionally reported in healthy subjects, in patients affected by autoimmune diseases, such as Graves' disease and systemic lupus erythematosus (SLE), and recently also in HIV-infected subjects. A 63-year-old woman was admitted to the hospital because of dyspnea, autoimmune thrombocytopenia and serum antinuclear autoantibodies. The clinical course and X-ray films of the chest were consistent with idiopathic pulmonary fibrosis. The evaluation of peripheral blood lymphocyte subsets showed low CD4+ cells by use of OKT4 (Ortho Mune) monoclonal antibody (30%, normal range 35-45) and normal values of the same CD4+ subset by use of OKT4A (Ortho Mune) and Leu3a (Becton Dickinson) monoclonal antibodies (48%, normal range 45-55), which are specific for a different epitope of CD4 molecule. These differences indicate that the patient is heterozygous for the OKT4 epitope deficiency on CD4+ lymphocytes surface. The routine use of a panel of monoclonal antibodies, such as OKT4, OKT4A, Leu3a, which recognize different CD4 epitopes, is suggested in order to perform an accurate evaluation of CD4+ lymphocyte subset in patients affected by immune-mediated disorders other than Graves' disease and SLE.