Implantation of Cultured Thymic Fragments in Patients With Acquired Immunodeficiency Syndrome

• Cultured thymic fragments were implanted in one patient with acquired immunodeficiency syndrome (AIDS)-related complex (ARC) and in eight AIDS patients with opportunistic infections (Ols, four patients), Kaposi’s sarcoma (KS, two patients), or both (two patients). Thereafter, objective clinical improvement was noted in one patient with 01, and a stable symptom-free condition was observed in the ARC patient and in two other patients with Ols. However, the ARC patient and two of the three patients with Ols developed infections three to six months after implantation. A fourth case of 01 and the patients with KS showed progression of the disease. Peripheral blood investigations for counts of total leukocytes, lymphocytes, and T-lymphocyte subsets as well as for lymphocyte stimulation with mitogens showed no changes interpretable as an improvement of the cellular immune deficiency status. We conclude that cultured thymic fragments have no distinct in vivo effect on the course of AIDS, except for a temporary clinical improvement or a period of stable condition in some patients with Ols

The thymus in "bare lymphocyte" syndrome : Significance of expression of major histocompatibility complex antigens on thymic epithelial cells in intrathymic T-cell maturation

Thymic biopsies from two patients with combined immunodeficiency and defective expression of HLA class I and class II antigens on blood mononuclear cells (“bare lymphocyte” syndrome) were investigated. This made possible an evaluation of the significance of HLA antigen expression in a detailed (immuno)histologic study. Both thymuses showed a normal lobular architecture with distinct cortex-medulla areas, well-differentiated epithelium, including ultrastructurally defined subtypes, and Hassall's corpuscles. Normal numbers of lymphoid cells were present and normal T-cell phenotype was found. Using anti-HLA-A,B,C antisera, confluent staining of the medulla (stroma and lymphocytes) was observed. One of the thymuses was found to be negative for HLA class II antigen expression: the other revealed only HLA-DR positivity of nonlymphoid cells in the medulla. These cells were not of epithelial nature as judged from double staining with anti-keratin antibody. There was no expression of HLA-DC/DS. These observations differ from findings in the normal thymus, wherein epithelial cells in the cortex carry HLA class I and class II antigens, and epithelial cells in the medulla express HLA class I, and for a minor part class II antigens. The results indicate a normal sequential acquisition of T-cell differentiation antigens in the thymus of both cases. It is suggested that the expression of HLA class I and class II antigens on epithelial cells in the normal thymus cortex does not play a significant role in the sequential acquisition of differentiation antigens on T lymphocytes