Heterogeneity of lymphocyte subpopulations in severe combined immunodeficiency. Evidence against a stem cell defect

Thirty years of primary immunodeficiencies in Turkey

Turkey, with its population of some 75 million, has a high rate of consanguineous marriages. Because the majority of the primary immunodeficiencies (PIDs) are inherited as autosomal recessive (AR) forms, the high consanguinity rate leads to a high prevalence of PID diseases in Turkey. The first pediatric immunology division was established in 1972, since then over 10 other immunology divisions have been established in different cities. Approximately 4,000 patients with possible PID are referred to these centers annually. The percentages of some of the major immunodeficiency groups and individual disease numbers among these patients differ somewhat in comparison with Western countries, likely because the relative incidences of PIDs with AR inheritance and of rare diseases are higher. These characteristics of the patient population, and our determination of differences in disease presentation and unusual features, have led us to undertake studies in collaboration with various centers in Western countries. These collaborations have contributed to the identification of the genes responsible for some rare immunodeficiencies, to the resolution of the genetic heterogeneity underlying conventional phenotypes, and to the description of new clinical phenotypes.

Human severe combined immunodeficiency: genetic, phenotypic, and functional diversity in one hundred eight infants

OBJECTIVE

To determine the relative frequencies of the different genetic forms of severe combined immunodeficiency (SCID) and whether there are distinctive characteristics of the particular genotypes.

STUDY DESIGN

The demographic, genetic, and immunologic features of 108 infants with SCID who were treated consecutively at Duke University Medical Center were analyzed.

RESULTS

Eighty-nine subjects were boys and 19 were girls; there were 84 white infants, 16 black infants, and 8 Hispanic infants. Forty-nine had X-linked SCID with mutations of common cytokine receptor gamma chain (gamma c), 16 had adenosine deaminase (ADA) deficiency, 8 had Janus kinase 3 (Jak3) deficiency, 21 had unknown autosomal recessive mutations, 1 had reticular dysgenesis, 1 had cartilage hair hypoplasia, and 12 (all boys) had SCID of undetermined type. Deficiency of ADA caused the most profound lymphopenia; gamma c or Jak3 deficiency resulted in the most B cells and fewest natural killer (NK) cells; NK cells and function were highest in autosomal recessive and unknown types of SCID.

CONCLUSIONS

Different SCID genotypes are associated with distinctive lymphocyte characteristics. The presence of NK function in ADA-deficient, autosomal recessive, and unknown type SCIDs, and low NK function in a majority of gamma c and Jak3 SCIDs indicates that some molecular lesions affect T, B, and NK cells (gamma c and Jak3), others primarily T cells (ADA deficiency), and others just T and B cells.

Pathology of the pancreas in severe combined immunodeficiency and DiGeorge syndrome: acute graft-versus-host disease and unusual viral infections

Review of autopsies of 28 children with severe combined immunodeficiency (SCID) or combined immunodeficiency (CID) and three with DiGeorge syndrome showed a high incidence of acute graft-versus-host disease (GVHD) in the pancreas. Acute GVHD (seven cases: four SCID, two CID, and one DiGeorge syndrome) was characterized by lymphocytes around large to medium ducts, damage to ductal epithelium (focal necrosis, reactive nuclear changes, inspissated secretions in duct lumens), and periductal edema. Changes were judged indeterminate but suspicious for GVHD when ductal damage was slight (six cases: three SCID, two CID, and one DiGeorge syndrome). All patients with pancreatic GVHD had received allogeneic bone marrow, fetal liver or thymus transplant, or nonirradiated blood products and had evidence of GVHD in other organs. Immunoperoxidase stain for HLA-DR showed strong-to-moderate staining of duct epithelium in two of four GVHD cases for which blocks were available. This change was nonspecific; weaker staining for HLA-DR was seen in cases with nonspecific abnormalities and in viral pancreatitis. Four cases had histological evidence of viral infection: two had cytomegalovirus pancreatitis, one had patchy parenchymal necrosis caused by adenovirus, and one had giant cell pancreatitis caused by parainfluenza virus. Mild nonspecific changes, such as focal fat necrosis or acinar dilatation, were seen in seven cases. One case had unexplained marked pancreatic atrophy and fibrosis. Acute pancreatic GVHD is not uncommon in autopsies of children with congenital immune deficiencies with GVHD of other organs; however, this finding may not have strong clinical implications in this group of patients. Careful attention to pancreatic ducts is necessary for diagnosis. Unusual viral pancreatitis may also be seen in this group, as well as nonspecific abnormalities.

Pathology of the liver in severe combined immunodeficiency and DiGeorge syndrome

Review of liver biopsy or autopsy material from 33 patients with severe combined immunodeficiency or combined immunodeficiency and four patients with DiGeorge syndrome revealed a wide range of hepatic pathology. The most common abnormality was graft-versus-host disease (16 patients), followed by viral infection (4 patients had adenovirus hepatitis, 3 had cytomegalovirus hepatitis). Centrilobular fibrosis with or without veno-occlusive disease was seen in five patients. Three patients had nonspecific hepatitis, four had changes attributed to total parenteral nutrition, and two had lymphoproliferative disorders involving the liver. Both patients with lymphoproliferative disorders had received transplants. Two patients had resolving necrosis probably secondary to non-A, non-B hepatitis. One had atypical mycobacterial infection. Hemosiderosis was a common nonspecific abnormality, seen in nine patients. All patients with hepatic graft-versus-host disease had received transplants or nonirradiated blood products. Hepatic graft-versus-host disease varied in severity from hepatic necrosis with destruction of both large and small bile ducts in a transfusion-associated case to subtle damage to interlobular bile ducts. Even minimal bile duct changes correlated with the clinical impression of graft-versus-host disease in these patients. Late chronic graft-versus-host disease was not seen in any patient, although acute graft-versus-host disease sometimes occurred late after transplant.

Genetics of human X-linked immunodeficiency diseases

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Humoral immunodeficiency in T-cell chronic lymphocytic leukemia. An immunologic assessment

The humoral antibody immunodeficiency in two patients with T-cell chronic lymphocytic leukemia (T-CLL) appeared to be the result of immunoregulatory abnormalities in the leukemic T-cell populations. Both patients had CD4+ CD45R+ "virgin" or suppressor-inducer T-CLL, but Patient 1 had hypogammaglobulinemia and Patient 2, immunoglobulin (Ig) M hypergammaglobulinemia. Although, CD25+ interleukin-2 (IL-2) receptors were present on leukemic T-cells of both patient, OKT9+ (CD71) transferrin receptors and OKT10 (CD38) activation antigens were found only on Patient 2's cells. Highly elevated amounts of IL-2 was secreted from phytohemagglutinin-stimulated and concanavalin A-stimulated T-cells in both patients. In Patient 1 with hypogammaglobulinemia, immune defects involve T-cells, first an intense suppressor activity on B-cell-induced IgM and IgG synthesis and, second, deficient production of B-cell growth factor (BCGF) and B-cell differentiation factor (BCDF). In Patient 2, highly elevated BCGF and IgM-specific BCDF was secreted by T-cells, a mechanism leading to IgM hypergammaglobulinemia in this patient. These studies stress the importance of BCGF and BCDF activity of leukemic T-cells in humoral antibody immunodeficiency disorders in T-CLL cases.

X-linked severe combined immunodeficiency. Diagnosis in males with sporadic severe combined immunodeficiency and clarification of clinical findings

Over 80% of infants with severe combined immunodeficiency (SCID) of unknown genetic etiology are males, yet less than a third of these affected males have a family history of X-linked disease. To help identify new mutations of the X-linked SCID gene and to provide genetic counseling, X chromosome inactivation patterns in T cells from 16 women who had sons with sporadic SCID were examined. Between 9 and 35 human/hamster hybrids that selectively retained the active human X chromosome were produced from the T cells of each woman and analyzed with an X-linked restriction fragment length polymorphism for which the woman in question was heterozygous. Exclusive use of a single X as the active X was seen in the T cell hybrids from 7 of the 16 women, identifying these women as carriers of X-linked SCID. Studies on additional family members confirmed the mutant nature of the inactive X and revealed the source of the new mutation in three families. To determine whether there were any laboratory characteristics that might differentiate the boys whose mothers were identified as carriers of X-linked SCID from those whose mothers were not, the clinical records of both groups were compared to each other and to a group of 14 boys with a family history of X-linked SCID. The most consistent finding in the 21 patients with X-linked SCID was an elevated proportion of B cells. These data demonstrate the high incidence of spontaneous mutation for the X-linked SCID gene and help clarify the characteristic presenting features of this disorder.

Severe T lymphocyte immunodeficiency associated with hypogammaglobulinemia: defective lymphokine secretion but enhanced autologous mixed lymphocyte reaction

The multiparameter immunologic study of T cells of a patient with acquired hypogammaglobulinemia was investigated, since he had a normal B-cell number and function. His peripheral blood lymphocytes were found to contain predominant CD4+ CD45R+ T cells with a clear deficiency of CD4+ CDw29+ as well as CD8+ T cells. His T cells proliferated in response to phytohemagglutinin (PHA) and pokeweed mitogen (PWM), but no immunoglobulin was secreted in PWM-induced patient's T-cell and normal B-cell differentiations. His T cells were also found to possess concanavalin A (Con A)-induced suppressor function when cocultured with normal T cells, as well as IgG-, IgA-, and IgM-specific suppressor function on PWM-induced normal T- and B-cell differentiations. The patient's T cells were found to secrete elevated amounts of interleukin-2 but failed to secrete two important B-cell stimulating factors, B-cell growth factor and B-cell differentiation factor, in response to PHA. An investigation of immunoregulatory T-cell function in the autologous mixed lymphocyte reaction (AMLR) and allogeneic mixed lymphocyte reaction (MLR) indicated that the patient's T cells produced an enhanced AMLR but were deficient in MLR. These results suggest that the abnormalities we have identified in this patient with hypogammaglobulinemia reflect an intrinsic defect of T cells in the humoral immune response to produce three major immunoglobulins.

Management of a novel immune deficiency with IL-2 therapy

The present study describes a female child, who had a primary defect in the ability of her T-cells to secrete interleukin-2. Numbers of B- and T-cells were normal, but their functions were severely deficient. The patient had decreased immunoglobulins and poor ability to mount antibody responses. Phytohemagglutinin (PHA) and antigen-driven lymphoproliferative responses were diminished and were correctable in vitro with exogenous IL-2. Upon stimulation with PHA the patient's lymphocytes expressed IL-2 receptors normally, but were grossly deficient in endogenous IL-2 production. The patient was diagnosed as having a form of severe combined immunodeficiency disease at 6 months of age. Two attempts at immune reconstitution by haploidentical bone marrow transplantation failed to result in sustained engraftment. At age 18 months, treatment was initiated with rIL-2 10,000 units/kg i.v. daily and gradually increased to 30,000 units/kg. A marked improvement was noted, clinically as well as in T-cell immune functions. The child has been maintained on rIL-2 treatment at home for the past year without significant adverse effects, and she is currently receiving 30,000 units/kg of rIL-2 three times a week. This case illustrates that IL-2 is a potentially useful therapeutic modality which can be safely administered for prolonged periods to children with primary immunodeficiency diseases.

Nonrandom X chromosome inactivation in B cells from carriers of X chromosome-linked severe combined immunodeficiency

X chromosome-linked severe combined immunodeficiency (XSCID) is characterized by markedly reduced numbers of T cells, the absence of proliferative responses to mitogens, and hypogammaglobulinemia but normal or elevated numbers of B cells. To determine if the failure of the B cells to produce immunoglobulin might be due to expression of the XSCID gene defect in B-lineage cells as well as T cells, we analyzed patterns of X chromosome inactivation in B cells from nine obligate carriers of this disorder. A series of somatic cell hybrids that selectively retained the active X chromosome was produced from Epstein-Barr virus-stimulated B cells from each woman. To distinguish between the two X chromosomes, the hybrids from each woman were analyzed using an X-linked restriction fragment length polymorphism for which the woman in question was heterozygous. In all obligate carriers of XSCID, the B-cell hybrids demonstrated preferential use of a single X chromosome, the nonmutant X, as the active X. To determine if the small number of B-cell hybrids that contained the mutant X were derived from an immature subset of B cells, lymphocytes from three carriers were separated into surface IgM positive and surface IgM negative B cells prior to exposure to Epstein-Barr virus and production of B-cell hybrids. The results demonstrated normal random X chromosome inactivation in B-cell hybrids derived from the less mature surface IgM positive B cells. In contrast, the pattern of X chromosome inactivation in the surface IgM negative B cells, which had undergone further replication and differentiation, was significantly nonrandom in all three experiments [logarithm of odds (lod) score greater than 3.0]. These results suggest that the XSCID gene product has a direct effect on B cells as well as T cells and is required during B-cell maturation.

Transient T-cell abnormality in a selective IgM-immunodeficient patient with Brucella infection

We describe here one 9-year-old female patient with an unusual form of selective IgM and CD4+ (OKT4+) helper/inducer T-cell immunodeficiency associated with Brucella infection. During the acute phase of Brucella infection, the percentage of infection. During the acute phase of Brucella infection, the percentage of peripheral blood lymphocytes (PBL) displaying OKT3+, OKT11+, and OKT4A+ phenotypes was decreased, and that of the OKT8+ cell was increased. These phenotypic T-cell abnormalities disappeared after antibiotic therapy in a 5-week period. However, the marked deficiency of CD4+ T cells and the IgM deficiency present during the acute phase of illness remained after recovery from illness. In vitro immunoglobulin production experiments during the acute phase of illness demonstrated that the patient's T cells lacked the capacity to provide helper/inducer function for normal B-cell differentiation to secrete IgM. The patient's T cells were also shown to possess IgM-specific suppressor cell activity on normal B- and T-cell differentiations. Thus impaired T-cell function was shown to be responsible for IgM-deficient antibody production. Defective interleukin 2 receptor expression and production by the patient's PBL in response to mitogenic stimulation also were present, indicating a severe defect in the patient's T-cell function.

Natural killer cell function and interferon generation in patients with primary immunodeficiencies

Patients with primary immunodeficiency disorders were evaluated for three aspects of natural defense: natural killer (NK) cells which lyse HSV-infected fibroblasts [NK(HSV-FS)], NK cells which lyse K562 tumor targets [NK(K562)], and interferon-alpha generation. In addition, capacity to make interferon upon challenge with other commonly used inducers was also evaluated. Most patients with severe combined immunodeficiency disease (SCID) and deficits of both T- and B-cell function demonstrated normal NK function with one or both targets. Six of eight SCID patients generated interferon-alpha at or below the lower limit of normal while only two made clearly normal levels. Six of 10 patients with Wiskott-Aldrich syndrome (WAS) had normal NK(K562) and five of 10 generated normal levels of interferon-alpha but all had severely deficient NK(HSV-FS). Patients with Bruton's agammaglobulinemia demonstrated normal NK and interferon generation, as did patients with common variable immunodeficiency, even when subdivided into patients with T-cell proliferative deficiencies and those with only hypogammaglobulinemia. Natural defense parameters may help categorize patients with SCID and WAS and help define these heterogeneous diseases.

Severe combined immunodeficiency with natural killer-cell predominance: abrogation of graft-versus-host disease and immunologic reconstitution with HLA-identical bone marrow cells

A 3 1/2-month-old infant with severe combined immunodeficiency was found to have an unusual blood lymphocyte phenotype. Thirty percent of her cells formed rosettes with sheep erythrocytes, but only 7.9% reacted with the pan T monoclonal antibody OKT3, and 5% reacted with an antibody (OKT4)-recognizing T-helper cells. Surprisingly 19.4% of her cells reacted with an antibody (OKT8)-recognizing T-suppressor cells and 94% reacted with OKT10 . Few reacted with other monoclonal antibodies detecting cellular activation antigens. Despite absence of T or B cell function, her monocyte-depleted blood lymphocytes caused a high degree of specific lysis of 51Cr-labeled K562 erythromyeloid cells in a natural killer-cell assay. Most of her lymphocytes were large and had azurophilic granules and a monocytoid nucleus. Because she had received a nonirradiated, unrelated red-cell transfusion 3 days earlier, 4.8 X 10(9) nucleated bone-marrow cells from her HLA-identical brother were given shortly after admission. Two days later a graft-versus-host reaction began but subsided completely within 3 days. On day 15 posttransplantation, a profuse secretory diarrhea began, accompanied by a rise in her serum IgE from 4 to 3000 IU. With engraftment, the number of T10+ cells and natural killer-cell function fell to normal, and full immunologic reconstitution was achieved.

Severe combined immunodeficiency disease: a pathological analysis of 26 cases

Autopsy material and clinical information were analyzed in 25 cases of untreated or unsuccessfully treated severe combined immunodeficiency disease and one case successfully treated by bone marrow grafting. Two cases were adenosine deaminase deficient and one was nucleoside phosphorylase deficient. The histological appearance of the thymus fell into four clearly recognizable patterns: simple dysplasia, dysplasia with corticomedullary differentiation, dysplasia with pseudoglandular appearance, and atrophic pattern. Three cases lacked lymph nodes and belonged to the category of thymic dysplasia with pseudoglandular appearance. From the data, the following conclusions can be made: (i) The thymic atrophic pattern is a phase in a dynamic process of which the end result is simple dysplasia or dysplasia with corticomedullary differentiation. (ii) The pseudoglandular pattern represents a disease process of early intrauterine onset. (iii) At least a proportion of the cases represent a T-cell defect rather than a lymphoid stem-cell defect. (iv) The lymphoid germinal centers are not the source of plasma cells. (v) The graft-versus-host reaction probably causes lymphoid cells depletion in lymph nodes and spleen.

Immunodeficiency diseases: head and neck manifestations

Infections of the upper respiratory tract are common to both the immunodeficient and the normal child during their development. The most common head and neck manifestations of immunodeficiency disease are recurrent suppurative otitis media, tonsillitis, sinusitis, rhinitis, and nasopharyngitis. Often the head and neck specialist is confronted with a child with one or more of these problems and must institute the appropriate therapy or decide on an avenue for further investigation. This paper outlines the major immunodeficiency state, discusses the immune defects thought to be responsible for the spectrum of clinical findings, and suggests a systematic approach to the evaluation of these difficult diseases. The recognition of immunodeficient individuals is an important step in their treatment so that adjunctive immunological therapy can be provided.

T system immunodeficiencies in infancy and childhood

Some problems concerning the diseases due to deficiencies of the T immune system in infancy and childhood are reviewed. The relationships between SCID and Nezelof syndrome and the pathogenesis of this group of diseases are particularly discussed.

Heterogeneity of b lymphocyte differentiation in severe combined immunodeficiency disease

Pokeweed mitogen-induced B lymphocyte differentiation in vitro into antibody secreting plaque-forming cells (PFC) was investigated in nine patients with severe combined immunodeficiency having variable proportions of circulating B lymphocytes. When cultured by themselves, the peripheral blood mononuclear cells did not respond to stimulation with pokeweed mitogen in any patient. In the presence of irradiated allogeneic T cells as helpers, however, PFC responses were elicited in lymphocyte cultures from peripheral blood and/or bone marrow in some patients. In one of these patients, results of allogeneic co-culture experiments were suggestive of genetically restricted suppressor cells. In a single patient with deficiency of the enzyme adenosine deaminase, PFC were generated in bone marrow lymphocyte cultures only when they were supplemented with exogenous adenosine deaminase and allogeneic helper cells. A parallel study of T lymphocyte differentiation in vitro performed in fractionated bone marrow cells was suggestive of arrested differentiation at different steps along the differentiation pathway. In two patients with evidence of functional B cell precursors, deficiencies of helper T cell function could be attributed to differentiation defects at the level of the stem cells in one and the thymus in the other. The findings reported here further substantiate the heterogeneity of the severe combined immunodeficiency disease syndromes.

Subpopulations of human T lymphocytes. XV. T lymphocytes with receptors for IgA (T alpha), a distinct subpopulation of T lymphocytes. Studies in patients with primary immunodeficiency disorders

A receptor for IgA was observed on a subset of T cells (T alpha) that is distinct from other T lymphocyte subsets, T mu or T gamma cells. IgA receptor on T alpha cells is blocked by IgA from human serum through its cytophilic attachment. Neither T mu nor T gamma cells, following an in vitro interaction with insoluble immune complexes during the process of purification and further incubation at 37 degrees C, changed their phenotypes to T alpha cells. However, some T gamma cells demonstrated transition to T mu cells. The numbers and proportion of T alpha cells in patients with selective IgA deficiency were either normal, increased or decreased. The significance of T alpha cell analysis in thirty-one patients with primary immunodeficiency disorders including those with selective IgA deficiency is discussed.

Immune status in Crohn's disease. 4. In vitro antibody dependent cell mediated cytotoxicity in peripheral blood

In Crohn's disease (CD) a potential etiopathogenetic role of the antibody dependent cell mediated cytotoxicity (ADCC) has been discussed. By means of a 51Cr release assay with an established human lymphoblastoid cell line as target, the in vitro ADCC activity was studied in the peripheral blood of 34 patients with CD. 11 patients with inflammatory bowel disease other than CD or ulcerative colitis (group D) and 45 sex and age matched healthy people served as controls. In unseparated mononuclear cell suspensions, we found a significantly lower ADCC activity in CD patients and in group D than in normals. Depletion of both phagocytic and plastic adherent cells, i.e. macrophages, resulted in complete normalisation of the ADCC activity in all patients of group D and also two-thirds of the CD patients. However, the remaining one third CD patients still exhibited ADCC activity below 1 standard deviation of normal. Most of these latter CD patients had highly active disease. Thus, this study showes that the general ADCC per se is normal in CD, except for a decrease in patients with high activity of disease. However, the normal general ADCC activity per se is significantly suppressed by phagocytic, plastic adherent cells. In this regard similar results were found in group D.

Immunoreconstitution by peripheral blood leukocytes in adenosine deaminase-deficient severe combined immunodeficiency

Transplantation of histocompatible allogeneic peripheral blood leukocytes resulted in successful reconstitution of an adenosine deaminase (ADA)-deficient, severe combined immune-deficient patient. Erythrocyte transfusions before the transplant were associated with a rise of serum immunoglobulin concentration to normal without improvement in T cell function. The patient received 5 x 10(7) peripheral blood mononuclear leukocytes/kg obtained from the histocompatible father by leukopheresis. 3 wk after the transplant the lymphocyte count, proportion of E rosetting lymphocytes, and the ADA content of the patient's mononuclear leukocytes became normal while the phytohemagglutinin-stimulated blastogenic responses improved and became normal 52 d after the transplant. Antibody response to diphtheria immunization and response to naturally acquired herpes simplex infection were normal while isohemagglutinins progressively increased. Immunization with a neoantigen, bacteriophage phiX 174, resulted in a small but definite antibody response but no amplification of the response after secondary immunization. A positive reaction to a skin test for Candida albicans developed. Erythrocyte deoxy ATP (dATP) concentration decreased during the course of erythrocyte transfusions. 9 mo after the transplant, the erythrocyte dATP was elevated to twice pretransfusion levels while mononuclear leukocyte dATP varied from normal to elevated during the first 4 mo of the posttransplant period, but remained normal during the last 8 mo. The improvement in immune function persisted during the 12-mo posttransplant observation period while the mononuclear leukocyte ADA concentration stabilized at approximately 0.25 of normal, which is similar to the enzyme activity of the donor cells. This in vivo study supports the hypothesis that lymphoid precursor cells are present in peripheral blood which may partially reconstitute an immune-deficient recipient.

Abnormal lymphocyte capping in a patient with severe combined immunodeficiency disease

Despite the presence of normal numbers and distribution of T and B lymphocutes and normal levels of serum immunoglobulins, a five-month-old infant failed to show any evidence of T-cell or B-cell immunity. In trying to identify a specific membrane abnormality as a potential cause of the immunologic dysfunction, we examined the lateral mobility of the cell-surface receptor for concanavalin A. In contrast to normal cells, in which the receptor is distributed uniformly over the cell surface, the patient's lymphocytes showed an unusually high accumulation of concanavalin A receptors in surface caps. This capping abnormality appeared in both T and B lymphocytes and was exaggerated by colchicine, an inhibitor of microtubule assembly. These findings support the theory that plasma-membrane-cytoskeleton interactions have a role in the expression of specific immunity; the findings also identify new areas that should be considered in trying to understand the primary immunodeficiency diseases.

Use of a human plaque-forming cell assay to study peripheral blood bursa-equivalent cell activation and excessive suppressor cell activity in humoral immunodeficiency

A plaque assay that detects human mononuclear blood cells producing immunoglobulin (Ig)M antibody to sheep erythrocytes was investigated for its usefulness in studying B-cell activation and regulation in 24 patients with humoral immunodeficiency. Cells from 3 of 15 patients with common variable agammaglobulinemia produced some plaques (range 40--160/10(6) cells; normal range 80--1240/10(6)), but those from the other 12, from all 7 with x-linked agammaglobulinemia and from the 2 with x-linked immunodeficiency with hyper-IgM failed to produce any detectable plaques. In co-cultures of patient and normal cells a very good correlation was seen between results of the plaque assay and an IgM biosynthesis assay in detecting excessive suppressor cell activity. Cells from 7 of 15 common variable agammaglobulinemics, from 3 of 7 x-linked agammaglobulinemics, and from both patients with hyper-IgM caused significant suppression of IgM biosynthesis and(or) plaque formation by normal cells. The observations in the last two groups and discordance for excess suppressor activity in identical twins with common variable agammaglobulinemia suggest that the activity develops secondarily to whatever their primary defects may be. Culturing non-T cells from common variable agammaglobulinemics exhibiting excessive suppressor cell activity with normal T cells resulted in plaque formation in four of five patients so studied; in all five the suppressor activity was found in the T-cell population. The availability of a plaque assay for the study of blood cells from immunodeficient patients provides a new probe to examine the cellular nature of such defects.

Immunoregulation in humans: control of antitetanus toxoid antibody production after booster immunization

Booster immunization of normal individuals with soluble tetanus toxoid resulted in the ability of the individuals' peripheral blood lymphocytes to synthesize immunoglobulin (Ig)G antitetanus toxoid antibody in vitro when stimulated by pokeweed mitogen. The capacity for this in vitro antitetanus toxoid antibody response developed within 14 days after booster immunization, reached a peak between days 36--50, and disappeared by day 60. The inability of pokeweed mitogen to stimulate antitetanus toxoid antibody synthesis in vitro before booster immunization was not due to excess suppression by thymus-derived (T) lymphocytes but reflected insufficient numbers of functionally specific helper T lymphocytes and bone marrow-derived (B) lymphocytes. Antigen-specific T-lymphocyte suppression and decreased B-lymphocyte function were associated with the observed reduction of in vitro synthesis of antitetanus toxoid antibody from 20--60 days post-immunization. The in vitro kinetics of antitetanus toxoid antibody synthesis paralleled the synthesis of total IgG in that stimulation by pokeweed mitogen was required and that antibody secretion into the medium initiated by day 4 and increased through day 9.

Polyclonal activation of human B lymphocytes in vitro by pokeweed mitogen: a simple technique for the simultaneous assessment of cell proliferation, generation of plasma cells, plaque-forming cells and immunoglobulin production

A simple technique has been worked out for the simultaneous assessment of cell proliferation, generation of plasma cells, plaque-forming cells and immunoglobulin production from single cultures of 1 X 10(6) human peripheral blood lymphocytes stimulated with pokeweed mitogen (PWM). Kinetic studies showed that number of cells, thymidine incorporation rate, number of plaque-forming cells against fluorescein-isothiocyanate-haptenated sheep erythrocytes and concentration of IgM and IgG in the supernatant peaked on the average between day 5 and 7 of culture. This technique is particularly suitable for the analysis of hypogammaglobulinaemias in infancy.

Severe combined immunodeficiency disease: a model of T-cell dysfunction

Studies in three patients with severe combined immunodeficiency disease (SCID) and normal adenosine deaminase demonstrated that the combined defect of both T- and B-lymphocyte function may reflect the lack of normal maturation of thymic epithelial cells. This results in the failure of initiation of T-cell differentiation and consequent failure of T-cell dependent maturation of B-lymphocytes to an antibody-secreting stage. SCID B lymphocytes were shown to be capable of generating a specific IgM-antibody response to two T-cell-dependent antigens in vitro under either of the following conditions: (a) provision of autologous T-helper cells which were induced following incubation of precursor cells on monolayers of cultured human thymic epithelium or (b) in the presence of allogeneic T-helper cells. Specific IgM anti-ovalbumin (OA) responses were also generated in the absence of provided T-helper cells when the antigen was insolubilized (Sepharose-OA). The antibody-secreting cells and their circulating precursors carried surface IgM, HLA and Ia-like determinants and proliferated in response to antigen. Identification of this form of SCID may be important when considering therapy and provides an excellent model for the study of the T-cell-dependent acquisition and expression of B-cell immunity.

Purinogenic immunodeficiency diseases: selective toxicity of deoxyribonucleosides for T cells

Deoxyadenosine at low concentrations and in the presence of an inhibitor of adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) is markedly toxic to lymphoblast cell lines of T cell origin but does not impair growth of B cell lines. Deoxyguanosine is also more toxic for T lymphoblasts. In the presence of deoxyadenosine or deoxyguanosine, elevation of the corresponding deoxyribonucleoside triphosphate (dATP or dGTP) occurs in T cell, but not in B cell, lines. The addition of deoxycytidine or dipyridamole results in lower dATP and dGTP levels and prevents deoxyribonucleoside toxicity. These findings provide a molecular basis for the immunodeficiency observed in individuals with several inborn errors of purine metabolism.

Antibody-dependent cellular cytotoxicity in primary immunodeficiency diseases and with normal leukocyte subpopulations. Importance of the type of target

To gain insight into a possible role for antibody-dependent cell-mediated cytotoxicity in vivo, we examined the ability of leukocytes from 28 patients with primary immunodeficiency and from 20 normal controls to lyse three different types of antibody-coated targets in vitro. Mean cytotoxic indices +/-1 SD elicited by unfractionated mononuclear cells from normal controls were 28.74+/-13.26 for human HLA antibody-coated lymphocyte targets, 42.79+/-8.27 for rabbit IgG antibody-coated chicken erythrocyte targets, and 47.58+/-10.34 for human anti-CD (Ripley)-coated O+ erythrocyte targets. Significantly (P=<0.05) lower than normal mean cytotoxic indices against lymphocyte targets were seen with effector cells from 10 patients with X-linked agammaglobulinemia (3.7+/-4.33), in 10 with common variable agammaglobulinemia (16.05+/-7.74), in 3 with immunodeficiency with hyper IgM (18.41+/-4.88), and in 2 with severe combined immunodeficiency (3.94+/-0.3). Antibody-dependent cytotoxicity against chicken erythrocytes was significantly (P=<0.05) lower than normal only in the common variable agammaglobulinemic group (33.33+/-12.3) and against human erythrocytes only in the common variable (34.36+/-9.59) and hyper IgM (27.54+/-0.66) groups. Rosette and anti-F(ab')(2) depletion studies with normal leukocytes indicated that a nonadherent, nonphagocytic, non-Ig-bearing, non-C receptor-bearing, Fc receptor-bearing lymphocyte was the only effector capable of lysing HLA antiboyd-coated lymphocyte targets. Patients with infantile X-linked agammaglobulinemia and severe combined immunodeficiency appear to have a marked deficiency in this type of effector cell function.

Chemotactic defects in severe combined immunodeficiency

Cellular and humoral components of leukotaxis were studied serially in four male infants with severe combined immunodeficiency disease. Two of the four, both lacking B and T cells initially, had a significant defect in neutrophil and monocyte chemotaxis. The other two, who had a high number of immunoglobulin-bearing cells (B cells), did not have these cellular abnormalities. It contrast, defective generation of chemotactic factor following endotoxin activation was observed in all patients. The defects were corrected coincident with or soon after successful engraftment of either bone marrow or fetal tissues. The reported deficiencies may be another manifestation of the heterogeneity in SCID.

Circulating thymic-hormone activity in congenital immunodeficiency

Circulating thymic-hormone activity was assayed by measuring Thy 1-2 antigen induction on null lymphocytes from athymic mice incubated with human plasma or serum. Plasma from 19 normal children aged under 10 had inductive activity equivalent to 10-6-16-2 ng thymopoitin/ml. Plasma from 15 infants were severe combined immuno-deficiency, 2 of whom had appreciable immunoglobulin synthesis, and from 2 infants with DiGeorge syndrome had little or no inductive activity. Successful reconstitution with thymus or bone-marrow grafts and with red-cell infusions (if adenosine-deaminase deficiency is present) was followed by a rise in circulating thymic-hormone activity.