Thymic aplasia with possible graft-versus-host disease

Cutaneous histiocytosis syndromes

Cutaneous histiocytosis may take two principal forms. It is either a benign proliferative process or a relentless, progressive process with a poor prognosis. In histiocytic medullary reticulosis, histiocytes demonstrate nuclear atypia and the outcome is uniformly fatal. Benign cephalic histiocytosis X causes lesions similar to those of histiocytosis X, but Langerhans' cells are absent. In congenital self-healing histiocytosis X, the Letterer-Siwe-like cutaneous infiltrate contains Langerhans' cells, but the lesions heal spontaneously without treatment. The nodular cutaneous lesions of juvenile xanthogranuloma appear in infancy and resolve without treatment; however, the higher percentage (10%) of associated ocular lesions may lead to glaucoma and blindness. In histiocytosis X, the cutaneous lesions show a marked proliferation of Langerhans' cells, with prognosis dependent on the patient's age and the extent of organ dysfunction. Patients who survive the acute form of the disease may develop diabetes insipidus, growth retardation, pulmonary fibrosis, and biliary cirrhosis. A subtle immunologic defect has been identified in patients with histiocytosis X, yet the pathogenesis of the disease is still speculative. Familial disease occurring in early infancy should be differentiated from complete or partial immunodeficiency syndromes. Guidelines for evaluating patients with cutaneous histiocytosis are reviewed.

XX T cells and XY B cells in two patients with severe combined immune deficiency

Immunologic evaluation of two unrelated male infants with clinical and laboratory evidence of severe combined immunodeficiency (SCID) revealed T cells with a mature phenotype in the peripheral circulation of both patients although both had biopsy evidence of thymic alymphoplasia. Both had a normal number of T cells with a cytotoxic/suppressor surface marker (OKT8) but very few T helper cells (OKT4). Lymphocyte stimulation with the mitogens PHA, Con A, and pokeweed or with allogeneic cells resulted in no proliferation. However, addition of T cell growth factor, plus the phorbol ester TPA, to lymphocytes cultured with the T cell mitogen PHA did result in some proliferation of T cells. In both cases these T cells demonstrated an XX female karyotype and were probably of maternal origin. In contrast, proliferating B cells stimulated with Epstein-Barr virus demonstrated a normal XY male karyotype. The possibility that severe combined immune deficiency in these patients was the result of graft-versus-host disease induced by maternal lymphocytes is discussed.

The MHC in human bone marrow allotransplantation

In this chapter, we have considered the theoretical and practical background of bone marrow transplantation. The immune response and its regulation by genes within the major histocompatibility complex, particularly of the I region of the mouse and of the HLA-D/DR region in man, is of central importance in both graft acceptance (rejection) and graft-versus-host disease. Methods which are available for typing alleles at the HLA-A, -C, -B, -DR and complotype (BF, C2, C4A, C4B) loci, have been considered in detail. The extent to which recombination affects specific alleles on haplotypes within families is discussed, as is the occurrence of linkage disequilibrium and extended haplotypes in populations of unrelated individuals. Because the HLA-DR and complotype region in man is thought to be critical for the success of bone marrow transplantation, methods for typing of HLA-D by both the HTC and PLT approaches have been examined. Although HLA-D/DR assignments are easily made in normal subjects, they are ambiguous in about 50 per cent of candidates for bone marrow transplantation, including, particularly, patients with aplastic anaemia, leukaemia, and severe combined immunodeficiency. In this setting, it is particularly important to obtain additional information by modification of HLA-D typing procedures and through complotype and GLO allele determinations in all family members. Finally, we can hope that there will be an increased possibility of using non-family donors through methods for removing cytotoxic T cells from donor marrow and through the identification, in the general population, of individuals who are genotypically similar or identical to the recipient. In this regard, the recognition that some 30 per cent of chromosome 6 in caucasians (50 per cent of individuals) bear extended haplotypes, which include a relatively fixed set of alleles particularly in the HLA-B, -DR, complotype and GLO regions, offers considerable promise.

Graft-versus-host reaction following blood product transfusion

The observation of graft-versus-host (GVH) reaction after platelet transfusion in a patient with Hodgkin's disease led us to analyze 38 reported cases in the literature, to outline prognostic factors and to characterize patients at risk. Overall mortality was 68 percent. It was higher among children (76 percent) than among adults (62 percent), and among patients with Hodgkin's disease and immune deficiency syndromes (88 percent) than among those with leukemias (23 percent, p less than 0.005). Following blood transfusions from normal donors, mortality was higher (88 percent) than after transfusions from donors with chronic myelocytic leukemia (25 percent, p less than 0.05). Minimal lymphocyte doses necessary to cause GVH reaction are in excess of 10(7)/kg. Adults seem more resistant to homografts than do children, and the host's cellular immune status is of major prognostic importance. Lymphocytes from donors with chronic myelocytic leukemia may be deficient, and after a threshold dose, the number of lymphocytes transfused does not correlate with clinical outcome. Effective prophylactic measures do exist for this complication but satisfactory therapy does not.

The spectrum of the DiGeorge syndrome

Clinical and autopsy data on 25 patients with DiGeorge syndrome and its variants are presented. Congenital heart disease was the most common presenting complaint; 15 patients came to medical attention in the first 48 hours of life because of cyanosis, cardiac murmurs, or tachycardia and tachypnea. Two unusual anomalies, interrupted aortic arch or truncus arteriosus, were seen in 17 patients. Clinically documented hypocalcemia associated with seizures was seen in ten patients, with a median age at onset of eight days. Fifteen of our 25 patients died at less than one month of age. Most of the patients surviving the first month of life developed purulent rhinitis, maculopapular rashes, failure to thrive, and developmental delay. Sixteen patients had major congenital anomalies not localized to the anterior neck and thorax; these anomalies included arhinencephaly, cleft lip, palate, or uvula, diaphragmatic abnormalities, hydronephrosis, malrotation of the gut and imperforate anus. The 24 autopsied cases constitute 0.7% of the 3,469 sequential postmortem studies done in the period 1950--1975 at The Children's Orthopedic Hospital and Medical Center.