The primary immunodeficiencies (1)

Immunologic dysfunction in the pathogenesis of periodontal diseases

Despite significant progress in our understanding of the pathogenesis and etiology of periodontal diseases, the nature and contribution of the immune system to this disorder remains unclear. Several studies provide evidence for either a protective or destructive rôle. These conflicting findings are difficult to reconcile, since most interpretations tend to argue for a static contributory rôle (i.e., either protective or destructive) of the immune system. Current theories on the rôle of the immune response do not address these conflicting findings as well as the contradictory observation of a detectable immune response in the face of persistent infection in these patients. In this article, we present a model, based on available data, for the contribution of the immune system to the pathogenesis of periodontal disease. This model ascribes a dynamic rôle for the immune response. As documented in other infectious diseases, it is entirely possible, for example, that a state of immunologic dysfunction may occur in the earliest stages of periodontal disease progression; this may then be followed by a period of active immune reactivity (humoral and/or cellular) that would represent either a delayed or depressed response. This model is discussed in conjunction with recent findings that several suspected periodontal pathogens are capable of producing immunosuppressive agents. Many of the apparently contradictory clinical observations concerning the host immune response to oral pathogens and its correlation (or lack of) with both the progression and severity of periodontal disease may be accounted for in this model.

Evaluation of immunity

Immunodeficiency disease is rapidly increasing in frequency. The AIDS epidemic, the increasing use of transplantation with immunosuppression, the aggressive immunotherapy, the persistent deficiencies after bone marrow transplantation--all contribute to the astronomically increasing numbers of patients with host defense failure. This review has presented my viewpoint as to the approaches which can be utilized by practitioners with varying focal points to provide diagnosis and maximize the potential for a cure today or at least to provide the beginnings of understanding from which will come the cures of tomorrow.

Selective expansion of a CD3+CD4-CD8- subpopulation in clinical groups associated with human immunodeficiency virus infection

T lymphocytes (CD3+) without expression of CD4/CD8 surface antigens have recently been described in the thymus and peripheral lymphoid organs. We have conducted a retrospective analysis of the literature, seeking quantitative variations in this T-cell subset in normal heterosexual controls, and in risk, pre-AIDS, and AIDS groups, by means of the subtraction [CD3-(CD4+CD8]) and the ratio 100 X [CD3-(CD4+CD8])/CD3. Dramatic T lymphocytopaenia in AIDS patients and the progressive decay of CD4+ lymphocytes and increase of CD8+ lymphocytes throughout the clinical spectrum of HIV infection have been confirmed. Furthermore, we hereby demonstrate the selective expansion of CD3+CD4-CD8- lymphocytes, directly related to the clinical state in different clinical groups of infected people when compared with controls (P less than 0.05). The inverse relationship between the CD3+CD4-CD8- cell subset and other mature T-cell subsets, mainly CD4+ (r = -0.49; P less than 0.01), suggests the existence of mutual regulatory interactions. These in vivo results, which are in agreement with those obtained in long-term infected cultures, cannot be explained by direct cytopathic effects of the virus on the very few infected cells. Thus, the implication of the expansion of these functional precursors on the prognosis for infected people, and the paradoxes of the immunodeficiency, such as lymphoproliferation and autoimmune features, are discussed.

Immunology for the clinical pharmacist

Major advances in the field of immunology within the past decade have led to greater understanding of the immune network. The immune system is finely balanced, with cells communicating both by direct contact and through soluble mediators. Drugs may exert their effects at different sites within the immune network. To understand fully how these drugs act and how side effects may occur, clinicians must comprehend the basic workings of the immune system.

Indications for immunotherapy

Underlying immunodeficiency should be suspected in every patient, irrespective of age, who has recurrent, persistent, severe, or unusual infections. Defects in immunity can be classified into primary or secondary disorders involving specific or nonspecific immune mechanisms. Several forms of primary and secondary immunodeficiency exist for which various immunotherapeutic modalities are available. Significant among these are immunoglobulins commercially available for intravenous infusion. Other therapies include transplantation of tissue such as bone marrow, fetal liver, and fetal thymus. Enzyme replacement therapy is being developed, as is the use of products unique to immunocompetent cells, such as thymus extract, thymosin, interleukins, and transfer factor. Forms of nonspecific immune modulators and stimulators are other possibilities, especially in the context of the immunotherapy of tumors.

Carrier detection in X-linked agammaglobulinemia by analysis of X-chromosome inactivation

We used a recently developed strategy to analyze patterns of X-chromosome inactivation in human cell populations in order to study female members of families with X-linked agammaglobulinemia--i.e., to detect the carrier state and to test the hypothesis that the disorder results from a defect intrinsic in the development of B cells. According to this strategy, recombinant-DNA probes simultaneously detect restriction-fragment-length polymorphisms and patterns of methylation of X-chromosome genes. Random X-inactivation patterns were observed in isolated peripheral-blood granulocytes, T lymphocytes, and B lymphocytes of women who were not carriers. In contrast, one of the two X chromosomes was preferentially active in the peripheral B cells, but not the T cells or granulocytes, of three carriers of the disorder. This observation strongly supports the hypothesis that X-linked agammaglobulinemia results from an intrinsic defect in B-cell development. Moreover, the analysis described here can be used for direct identification of carriers in families with this disease.

The arrangement of immunoglobulin and T cell receptor genes in human lymphoproliferative disorders

Immunoglobulin and T cell antigen receptor genes in their germ-line form are organized as discontinuous DNA elements that are joined by recombinations during lymphocyte development. The analysis of immunoglobulin gene structure and arrangement has been of great value in the study of human lymphoid neoplasms. The analysis of rearranged immunoglobulin and T cell receptor genes has been of value in defining the lineage (T or B cell) of neoplasms that were of controversial origin previously, determining the clonality of abnormal lymphocyte proliferations, diagnosing and monitoring the therapy of lymphoid malignancies, determining the state of maturation and the causes for failure of maturation of cells of the B cell series, and providing major insights into the cause of malignant transformation of B and T lymphoid cells. Thus, the application of this molecular genetic approach has great potential for complementing conventional marker analysis, cytogenetics, and histopathology, thus broadening the scientific basis for the classification, diagnosis, and monitoring of the therapy of lymphoid neoplasia.

Defects in cell-mediated immunity

Defects in cell-mediated immunity result in remarkable susceptibility to opportunistic infection in contrast to the recurrent pyogenic infections observed in children with defects in antibody-mediated immunity. The major congenital defects in T lymphocytes are presented.

Susceptibility to infections in children with selective IgA- and IgA-IgG subclass deficiency

This study included 36 children with IgA-deficiency, increased susceptibility to infections and/or other disorders. Recurrent, usually bacterial infections were noticed in 23 out of 26 patients (88%) with complete and in 7 out of 10 patients (70%) with partial IgA-deficiency. All patients with severe infections had complete IgA-deficiency. Complete IgA-deficiency was also present in the six children who had autoimmune disorders associated with recurrent infections. In 22 out of the 36 patients studied the serum could be analysed for concomitant IgG subclass deficiencies: one patient had marked decrease of IgG2. In a second patient IgG4 was not detectable. Two patients had combined IgG2-IgG4-deficiency. In a girl with severe acute and chronic infections and relapsing idiopathic thrombocytopenic purpura, IgA-IgG2-IgG4-deficiency was found to be the prodromal stage of common variable immunodeficiency with panhypogammaglobulinaemia.

Humoral immunodeficiency

Humoral (or antibody) immunodeficiency syndromes may occur as apparent congenital or acquired abnormalities, with deficiencies in all or in only some classes of immunoglobulins. Most patients are recognized because of recurrent infections with high-grade extracellular encapsulated bacterial pathogens, but some with selective IgA deficiency or with transient hypogammaglobulinemia of infancy may have few or no infections. Although general population statistics are not available, most defects are thought to be rare; humoral immunodeficiency is more prevalent than cellular immunodeficiency, possibly due to early death from the latter defects. Disorders affecting B-cell function may be inherited as X-linked recessive or as autosomal traits. Although considerable information exists about such defects at a functional and cellular level, the primary biologic errors are as yet unknown for all of them. Apparent abnormalities of B-cell maturation and/or intrinsic B-cell malfunction are seen in a majority of these defects. The heterogeneity of B-cell morphology and function in large pedigrees of patients with X-linked agammaglobulinemia makes it unlikely that the defect is due to a distinct gene rearrangement abnormality at a specific stage of B-cell maturation. Early recognition of B-cell deficiency and institution of adequate immunoglobulin replacement therapy can prevent extensive damage to the lungs and other life-threatening problems from infection and allow a relatively normal childhood and adult life.

Familial Burkitt's lymphoma. Association with altered lymphocyte subsets in family members

Two sisters in a white American family died of Burkitt's lymphoma at ages 11 and 22 years, after dramatic but transient responses to chemotherapy. Studies of peripheral blood from two healthy brothers and the mother showed an increased percentage of polyclonal B cells (13 to 28 percent; normal, less than 10 percent), and a decreased helper:suppressor T cell ratio (1.0 to 1.5; normal, 1.5 to 2.5). The mother and one brother also had a low fraction of total circulating T cells (24 to 45 percent; normal, 60 to 75 percent). An inherited disturbance of the lymphocytes in family members may have predisposed the sisters to Burkitt's lymphoma; no environmental carcinogens were identified.

Immunodeficiency: immunoregulation and immunogenetics

During the past decade, our knowledge of normal immunologic development and function as well as disorders that lead to immunodeficiency has expanded rapidly as a result of the interplay between studies of the immune system in animals and studies of patients with immunodeficiency diseases or with malignancies of the cells of the lymphoid system. The study of immunodeficiency diseases has been particularly valuable in defining the critical stages in the differentiation of stem cells into mature lymphoid effector cells and the roles played by different subpopulations of cells in regulating the immune response. Our understanding of the immunodeficiency diseases has been facilitated by a number of important advances: (a) The identification of distinct surface determinants on lymphoid cells has led to improved procedures for the isolation of defined lymphoid cell subpopulations; (b) the demonstration that both T- and B-cell populations encompass subpopulations of lymphocytes with different and at times opposing functions; (c) the development of in vitro techniques to assess the functional behavior of isolated lymphoid subpopulations; and (d) the isolation and characterization of genes encoding immunoglobulin molecules and the antigen-specific T-cell receptor, thus defining at a molecular level the mechanisms leading to antibody diversity and to the organization of a recognition unit on T lymphocytes. These advances have not only been important for our understanding of the pathogenesis of immunodeficiency in patients with congenital and acquired immunodeficiency disorders, but have also provided the scientific basis for more rational approaches to the diagnosis and therapy of these disorders. This report will review (a) the defects in cellular maturation, cellular interaction, and cellular biosynthesis that have been observed in patients with immunodeficiency diseases; (b) the immunoglobulin gene rearrangements that are involved in the generation of antibody diversity; (c) the structure and genetic basis for the generation of antigen-specific T-cell receptors; and (d) potential future applications of molecular genetic approaches to the definition of the pathogenesis and to the treatment of immunodeficiency diseases.

Echovirus polymyositis in patients with hypogammaglobulinemia. Failure of high-dose intravenous gammaglobulin therapy and review of the literature

A 29-year-old man with X-linked hypogammaglobulinemia was treated with prednisone and methotrexate for polymyositis. Subsequently, it was established that disseminated echovirus 11 infection was causing the polymyositis. Treatment with large doses of intravenous gammaglobulin did not result in improvement. Viral cultures of blood, urine, and cerebrospinal fluid gave positive results throughout treatment and at postmortem examination. Multiple cultures of other tissues, including muscle, also gave positive results at postmortem examination. Severity of infection and treatment with prednisone and methotrexate prior to referral, diagnosis, and gammaglobulin treatment may explain the lack of response. A review of 23 cases of echovirus infection in patients with hypogammaglobulinemia revealed that the infection in these patients may cause meningoencephalitis or a polymyositis-like syndrome or both. Treatment with immunosuppressive agents, the standard therapy for polymyositis, is contraindicated, and intravenous or intraventricular gammaglobulin or both may be helpful.

[Biermer's disease and selective IgA deficiency. Apropos of a case]

The authors report a case of pernicious anaemia in a 41-year old white man; this case has particular features: rise in mean corpuscular volume, neurological manifestation 8 and 2 years respectively before diagnosis, association with selective IgA deficiency. Relations between pernicious anaemia and immunoglobulin deficiency are discussed.

Hypogammaglobulinemia with hyper-IgM, severe T-cell defect, and abnormal recirculation of OKT4 lymphocytes in a girl with chronic lymphadenopathy

We describe here one 8-year-old girl with an unusual form of immunodeficiency, characterized by hypogammaglobulinemia with hyper-IgM, severe T-cell defect, and chronic lymphadenopathy. Patient's B cells failed to produce IgG or IgA in vitro following stimulation with either pokeweed mitogen or Epstein-Barr virus, suggesting an intrinsic B-cell defect. Abnormal T-cell function was demonstrated by impaired in vivo delayed type hypersensitivity, reduction of mitogen-induced proliferation and interleukin 2 production, reduction of interferon-gamma production, and marked decrease of circulating OKT4+ cells. The latter cells were found in normal proportion in the patient's lymph node tissue. This finding suggests that the decrease of OKT4+ cells in peripheral blood was due to the abnormal recirculation of these cells. The identity of this syndrome with the infantile form of the acquired immunodeficiency syndrome was apparently ruled out by the failure to demonstrate HTLV-III-related sequences in patient's lymphocytes or virus-specific serum antibodies.

Mapping of the X-linked agammaglobulinemia locus by use of restriction fragment-length polymorphism

A molecular linkage analysis in 11 families with X-linked agammaglobulinemia (XLA) localized the XLA gene to the proximal part of the long arm of the human X chromosome. Significant linkage was detected between XLA and loci defined by two polymorphic DNA probes called 19-2 for the DXS3 locus and S21 for the DXS17 locus. Both localize to the region Xq21.3-Xq22. Most likely recombination distances (theta) and associated logarithm of the odds (lod) scores for the XLA-DXS3 and XLA-DXS17 pairs were theta = 0.04 morgans (lod, 3.65) and theta = 0 (lod, 2.17), respectively. Tight linkage between XLA and the locus DXS43 defined by the X short arm probe D2 (localized to Xp22-Xp21) was strongly excluded and we obtained no evidence for significant linkage between XLA and any other X short arm probe. The probe pair 19-2 and S21 should be informative for molecular linkage-based analysis of XLA segregation in the majority of families afflicted with this disorder.

Phenotypically immature IgG-bearing B cells in patients with hypogammaglobulinemia

We investigated the prevalence of phenotypically immature IgG B cells (i.e., coexpressing surface IgG and IgM) in the peripheral blood of 12 patients with hypogammaglobulinemia and in normal individuals. Patients had ataxia-telangiectasia (N = 1), hyper-IgM combined immunodeficiency (N = 1), or common variable immunodeficiency (CVI). IgG/IgM-positive B cells were evaluated by two-color immunofluorescence using fluorescein- or rhodamine-conjugated goat antiserum; to minimize artifacts due to in vivo cytophilic binding of autologous IgG, cell-bound cytophilic Ig were eluted at pH 4 and Fc receptors were blocked by heat-aggregated rabbit IgG before fluorescent staining. All patients, except two with late-onset CVI, had markedly increased proportions of double-stained IgG B cells (56 to 100% of IgG-bearing B cells) in comparison with normal individuals (11 to 33%).

Relationship between an enhancer element in the human antithrombin III gene and an immunoglobulin light-chain gene enhancer

Enhancers, cis-acting transcriptional control elements have been described in both viral and cellular genes. They influence transcription in a quantitative fashion, act over relatively large distances (several kilobases, kb) and behave independently of their position and orientation. Enhancers have been described in immunoglobulin, chymotrypsin and insulin genes. They bear little homology with each other except for an 8-base pair (bp) 'consensus' core element, GTGGAAATTTG (refs 10, 11), but even this element is sometimes non-homologous. I have searched for such elements in the human antithrombin III (AT-III) gene. AT-III is an important coagulation protein which inactivates thrombin. It is produced by the liver and, to a lesser extent, by the kidney. Here, I report that the 5' flanking region of the AT-III gene encodes a segment homologous with the enhancer containing the joining-constant kappa (J kappa-C kappa) intron of immunoglobulin kappa-chain genes. This extensive homology suggests the existence of regulatory factors that recognize common DNA sequences in lymphoid tissues and in those which express AT-III.

Central nervous system echovirus infection in Bruton's X-linked hypogammaglobulinemia

A patient with Bruton's X-linked hypogammaglobulinemia, who developed the typical syndrome associated with systemic echovirus 3 infection whilst on routine intramuscular gammaglobulin replacement therapy, is described. Following regular infusions of specific antibody-containing plasma from his spouse, he has shown sustained clinical improvement over a period of two years, and is, therefore, one of the very rare cases with this syndrome to survive for more than a few months.

Severe combined immunodeficiency: treatment by bone marrow transplantation in 15 infants using HLA-haploidentical donors

In 15 infants with severe combined immunodeficiency (SCID), immunological reconstitution was attempted by bone marrow transplantation (BMT) from HLA-haplo-identical parents. To prevent graft versus host disease (GvHD), marrow grafts were depleted of contaminating T-lymphocytes using lectin agglutination and rosette formation with sheep red blood cells. Thirteen patients received transplants without undergoing prior cytoreductive conditioning. Eleven of these developed donor-dependent T-cell functions, two failed to do this. One of these two as well as two further patients received cytoreductive treatment prior to repeat and to first transplants and in two, complete lymphohemopoietic reconstitution was observed. Of the 15 patients who received transplants, 11 are currently alive. Two recently treated patients remain in the hospital, nine are at home with stable T-cell functions. Normal humoral immune functions have developed upto now in three patients. In the others, gamma globulins are regularly substituted. Complications of acute or chronic GvHD were not observed with the exception of one case who developed transient GvHD of the skin. These results suggest that in a majority of patients with SCID, T-cell functions can develop without GvHD following haploidentical, T-cell-depleted BMT. Exceptional patients require preconditioning to allow donor cell engraftment, an approach that also appears to facilitate reconstitution of humoral immune functions.

Thymic non-lymphoid cells

In formulating this summary of our simon-pure knowledge of the structure/function relationships in the thymus, we decided that the time may have come to introduce a suitable dose of cynicism to balance the sometimes hopeless optimism of the past. Are the non-lymphoid cells of the thymus necessary for thymic function? Probably, but not to the extent or uniqueness that some authors including ourselves have previously claimed; T cells can probably differentiate in other tissues but may acquire their preference for MHC class II in the thymus. Mouse thymic lymphoid cell traffic and surface phenotype has recently been summarized pictorally by Scollay and Shortman [95]. Briefly stated, within the thymus, cells are hatched, matched and then dispatched. Minimally, the non-lymphoid cells act either as scenically varied obstacles along the way, nurseries for newborn T cells, or as tombstones for life's disenfranchized, effete and autoaggressive thymocytes. Hassall's corpuscles are morphological structures unique to the thymus, which are most useful to medical students for identification of this tissue. Their function remains one of life's great mysteries. Morphologically, they are suitable companions to the more recently described strange multicellular complexes of lymphocytes and epithelial cells which might be functionally important. The thymus of the much studied inbred, environmentally mollycoddled, laboratory mouse has been often and majestically described. It is probably typical for that of man and most mammals. It may, however, be unrepresentative of the thymus of stressed and parasitized wild animals. Diseases of the thymus generally can be categorized as not having enough thymus, having a neoplastic thymus or having a thymus which does not work properly. The bottom line in our knowledge of thymic nonlymphoid cells is that if you are born without them, you get sick and die; unless, of course, you are a nude mouse in Omaha, in which case you just freeze to death.

Errors of morphogenesis and inborn errors of immunity 20 years after the discovery of DiGeorge anomaly

The heuristic concept of "inborn errors of metabolism" was introduced more then 70 years ago and by analogy has prompted the more recent introduction of the term "inborn errors of immunity". It is now well recognized that many inborn errors of immunity can be considered inborn errors of metabolism. Typically, many forms of severe combined immunodeficiency result from adenosine deaminase deficiency, i.e., an inborn error of purine metabolism. On the other hand, errors of immunity are often associated with "errors of morphogenesis", resulting from an intrinsically abnormal developmental process (malformation), a secondary or extrinsic interference with originally normal development (disruption), or an abnormal organization of cells into tissues (dysplasia). Twenty years after the original description, the DiGeorge anomaly should be considered an inborn error of morphogenesis and immunity due either to disruption or less frequently to malformation. In other immunodeficiencies, such as ataxia telangiectasia, the morphologic and immunologic errors result from a dyshistogenesis, i.e., dysplasia. Also, true malformation syndromes, such as Down's syndrome, are consistently associated with immunodeficiency.

Immunodeficiencies associated with errors in purine metabolism

The genetic deficiencies of adenosine deaminase and purine nucleoside phosphorylase lead to blocks in the purine pathway. The intracellular accumulation of deoxynucleosides and deoxynucleotides is toxic to both dividing and nondividing lymphocytes via multiple mechanisms. T-lymphocytes are uniquely sensitive to purine-mediated cytotoxicity because of a functional imbalance of phosphorylating and dephosphorylating enzymatic activities. These inborn errors or purine metabolism are rare disorders. The study of these conditions, however, has uncovered unique enzymatic properties of lymphocytes and lymphocyte subclasses. A better understanding of the mechanisms of lymphocytotoxicity in these two purine enzyme defects may lead to better modes of therapeutic manipulation of the immune system.

Acquired immune deficiency syndrome in childhood

The acquired immunodeficiency syndrome has been observed with increasing frequency in children with associated hemophilia, high-risk environmental backgrounds, and blood transfusions. AIDS should be considered in the differential diagnosis of childhood immunodeficiency, and it must be distinguished from congenital disorders. We emphasize the importance of epidemiologic, clinical, and laboratory data in diagnosis and aggressive management of infectious complications. The relationship between human retrovirus infection and AIDS remains to be precisely defined, especially with regard to cofactors that may play a role in the development of severe immunodeficiency following exposure to the agent.

Respiratory infections may reflect deficiencies in host defense mechanisms

Serious respiratory tract infections are rare in the healthy individual and most of the nuisance morbidity that occurs results from nasopharyngeal viral infections that many people get once or twice a year. The economic impact from these upper respiratory tract infections is appreciable, however, in terms of absenteeism from school or work, but unfortunately there is little that can be done to ward them off in a practical way. Pneumonia is an infrequent lifetime experience for most non-smoking adults and when it occurs, unusual circumstances may pertain--a particularly virulent microorganism is in circulation, or perhaps one has been exposed to a newly recognized germ, such as has occurred with Legionella species in the past 8 years or so. What protects us the great majority of the time is a very effective network of respiratory tract host defenses. These include many mechanical and anatomical barrier mechanisms concentrated in nose and throat; mucociliary clearance, coughing and mucosal immunoglobulins in the conducting airways and in the air-exchange region of the alveolar structures, phagocytes, opsonins, complement, surfactant and many other factors combine to clear infectious agents. The ability to mount an inflammatory response in the alveoli may represent the maximal and ultimate expression of local host defense. In some way these host defenses are combating constantly the influx of micro-organisms, usually inhaled or aspirated into the airways, that try to gain a foothold on the mucosal surface and colonize it. But many general changes in overall health such as debility, poor nutrition, metabolic derangements, bone marrow suppression and perhaps aging promote abnormal microbial colonization and undermine the body's defenses that try to cope with the situation. It is a dynamic struggle. The departure from normal respiratory health may not be obvious immediately to the patient or to the physician and repeated episodes of infection or persisting symptoms of cough, expectoration and sinus or ear infections may develop before serious assessment of the situation is taken and appropriate diagnosis gotten underway. Obvious explanations for respiratory infections may be apparent and, nowadays, side effects from antineoplastic chemotherapy or immunosuppressive therapy for a variety of diseases that create an immunocompromised host are common. In a few subjects, especially young adults who present with a cumulative history of frequent but mild infections in childhood and youth, a subtle deficiency in host defenses may exist and have been partially masked because of attentive pediatric medical care and prompt use of broad spectrum antibiotics.(ABSTRACT TRUNCATED AT 400 WORDS)