sirolimus and Severe-Combined-Immunodeficiency

The golden standard for functional evaluation of immunodeficiencies is the incorporation of [(3)H]-thymidine in a proliferation assay stimulated with mitogens. Recently developed whole blood proliferation assays have the advantage of parallel lymphocyte lineage analysis and in addition provide a non-radioactive alternative. Here we evaluate the Flow-cytometric Assay for Specific Cell-mediated Immune-response in Activated whole blood (FASCIA) in a comparison with [(3)H]-thymidine incorporation in four patients with severe combined immunodeficiency. The threshold for the minimum number of lymphocytes required for reliable responses in FASCIA is determined together with reference values from 100 healthy donors when stimulated with mitogens as well as antigen specific stimuli. Finally, responses against PWM and SEA+SEB stimuli are conducted with clinically relevant immunomodulatory compounds. We conclude that FASCIA is a rapid, stable and sensitive functional whole blood assay that requires small amounts of whole blood that can be used for reliable assessment of lymphocyte reactivity in patients.

Topics: B-Lymphocytes; Cell Proliferation; Dexamethasone; Enterotoxins; Flow Cytometry; Humans; Immunosuppressive Agents; Interferon-gamma; Interleukin-17; Lymphocyte Activation; Lymphocyte Count; Pokeweed Mitogens; Reproducibility of Results; Severe Combined Immunodeficiency; Sirolimus; T-Lymphocytes; Tacrolimus

The first successful demonstration that effective T cell depletion can enable immune reconstitution without causing graft versus host disease (GVHD) was achieved in 1980 using lectin-separated hematopoietic stem cells. In leukemia patients undergoing supralethal radio- and chemotherapy, T cell-depleted transplants are vigorously rejected by residual host T cells; this barrier was first overcome in 1993 by the use of megadose stem cell transplants. This clinical observation can be explained, in part, by the demonstration that cells within the CD34 compartments, as well as their immediate early myeloid progeny, are endowed with veto activity. Engraftment of mismatched hematopoietic stem cells following reduced intensity conditioning, still represents a major challenge. Progress has been made recently by using anti-3rd party veto CTLs and T regulatory cells.

Topics: Animals; Antigens, CD34; CD4 Antigens; Hematopoietic Stem Cell Transplantation; Hematopoietic Stem Cells; HLA Antigens; Humans; Immune Tolerance; Interleukin-2 Receptor alpha Subunit; Leukemia; Lymphocyte Depletion; Mice; Severe Combined Immunodeficiency; Sirolimus; T-Lymphocytes, Cytotoxic; T-Lymphocytes, Regulatory