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An 8-month-old white female infant with Pneumocystis carinii pneumonia had a normal blastogenic response to mitogens but no response to a variety of antigens, as well as a poor response to allogeneic cells in one-way mixed lymphocyte culture assays. The patient's mononuclear cells had defective class I (HLA-A, -B, -C) and absent class II (HLA-D) antigen expression on their surface, thus establishing the diagnosis of HLA-deficient severe combined immune deficiency (bare lymphocyte syndrome). Family HLA typing, in vitro stimulation of patient mononuclear cells, and sequence-specific oligonucleotide probe hybridization allowed the patients HLA phenotype to be determined. An unrelated bone marrow donor whose phenotype matched at all but a single A locus was found. The patient was conditioned with busulfan and cyclophosphamide, followed by infusion of T-cell-depleted bone marrow cells. The patient has been infection free with a successful marrow graft documented by HLA typing and chromosomal analysis. Sequence-specific oligonucleotide probe hybridization allows determination of the HLA phenotype in patients with HLA-deficient severe combined immune deficiency which, in turn, makes marrow transplantation an option for the reconstitution of these patients' immune system.

Three human fetuses were treated by stem cell transplantation from fetal liver. Two of them had severe immunodeficiency disease and the third one had thalassemia major. All three in utero transplants were followed by engraftment. No adverse effect was seen. The three patients are now born: the first one is cured, the two other ones are still under investigation. This procedure, for the first time used in humans, is therefore shown to be an effective and safe therapy of inherited diseases, during early fetal development.

The treatment of choice for certain immunodeficiency syndromes and hematological disorders is bone marrow transplantation (BMT). The success of BMT is influenced by the degree of HLA compatibility between recipient and donor. However, aberrant expression of HLA sometimes makes it difficult, if not impossible, to determine the patient's HLA type by standard serological and cellular techniques. We describe here the application of new molecular biological techniques to perform high resolution HLA typing independent of HLA expression. A patient with HLA-deficient severe combined deficiency was HLA typed using in vitro amplification of the HLA genes and sequence-specific oligonucleotide probe hybridization (SSOPH). Two major advances provided by this technology are:detection of HLA polymorphism at the level of single amino acid differences; and elimination of a requirement for HLA expression. Although the patient's lymphocytes lacked class II HLA proteins, polymorphism associated with DR7,w53;DQw2;DRw11a (a split of DR5), w52b (a split of DRw52);DQw7 were identified. The patient's class I expression was partially defective, and typing was accomplished by a combination of serological (HLA-A and -C) and SSOPH analysis (HLA-B). Complete patient haplotypes were predicted after typing of family members [A2;B35(w6); Cw4; DRw11a(w52b);DQw7 and A2;B13(w4); Cw6;DR7(w53); DQw2]. Potential unrelated donors were typed and a donor was selected for BMT.