Genetic control of suppressor lymphocyte function in myasthenia gravis: relationship of impaired suppressor function to HLA-B8/DRW3 and cold reactive lymphocytotoxic antibodies

Brazilin augments cellular immunity in multiple low dose streptozotocin (MLD-STZ) induced type I diabetic mice

Brazilin, an active principle of Caesalprenia sappan, was examined for its immunopotentiating effects in multiple low dose streptozotocin (MLD-STZ) induced type diabetic mice. Brazilin was intraperitoneally administered for 5 consecutive days to MLD-STZ induced type I diabetic mice. Delayed type hypersensitivity, Con A-induced proliferation of splenocytes and mixed lymphocyte reaction, which had been decreased in diabetic mice, were significantly recovered by the administration of brazilin. Brazilin increased IL-2 production without affecting suppressor cell activity. Con A-induced and IL-2-induced expression of high affinity IL-2 receptors were also enhanced by brazilin. These results indicate that brazilin augments cellular immune responses, which are suppressed in the MLD-STZ induced type I diabetic mice, by increasing IL-2 production and responsiveness of immune cells to IL-2.

Ocular myasthenia: a protean disorder

Ocular myasthenia is a localized form of myasthenia clinically involving only the extraocular, levator palpebrae superioris, and/or orbicularis oculi muscles. Ocular manifestations can masquerade as a variety of ocular motility disorders, including cranial nerve and gaze palsies. A history of variable and fatiguable muscle weakness suggests this diagnosis, which may be confirmed by the edrophonium (Tensilon) test and acetylcholine receptor antibody titer. Anticholinesterases, corticosteroids and other immunosuppressive agents, and other therapeutic modalities, including thymectomy and plasmapheresis, are used in treatment. As the pathophysiology of myasthenia has been elucidated in recent years, newer treatment strategies have evolved, resulting in a much more favorable prognosis than several decades ago. This review provides historical background, pathophysiology, immuno-genetics, diagnostic testing, and treatment options for ocular myasthenia, as well as a discussion of drug-induced myasthenic syndromes.

HLA type is not indicative for the effect of thymectomy in myasthenia gravis

The frequency of HLA types in a selected group of 40 patients with myasthenia gravis in relation to the effect of thymectomy and also to gender, and thymus histology was studied. As generally described we found a significant increase in the frequency of HLA-A1, HLA-B8, HLA-DR3 and HLA-DQ2 in the total group. There were no further differences between subgroups of patients, which demonstrates that HLA type is not indicative for the effect of thymectomy in myasthenia gravis.

Defective T lymphocyte function in nonthymectomized patients with myasthenia gravis

In vitro functional properties of peripheral blood mononuclear cells were evaluated in 29 patients with myasthenia gravis and in 11 healthy controls. Spontaneous cell proliferation was higher in patients than in controls. The production of interleukin-2 and interferon-gamma and the proliferative response to different mitogens were reduced in the patients. A positive correlation was found between the production of interleukin-2 and interferon-gamma. These defects in T cell function were the most pronounced in nonthymectomized patients. Patients with severe disease had a higher percentage of cells bearing the interleukin-2 receptor and a higher spontaneous production of tumor necrosis factor alpha in cell culture than in patients with mild disease. There was no difference between patients and controls in the level of soluble interleukin-2 receptor in cell culture supernatants or in sera. The results indicate a partially suppressed T cell function in myasthenia gravis. This defect was less pronounced in patients studied after thymectomy.

Major histocompatibility complex genes influence the outcome of HIV infection. Ancestral haplotypes with C4 null alleles explain diverse HLA associations

Several alleles at multiple HLA loci have been found to be associated with infection with human immunodeficiency virus (HIV): HLA A1; B8, B35; Cw7, Cw4; DR1, DR3 and DQ1, are associated with particular disease manifestations and/or disease progression. Furthermore, in a pilot study we have shown an increase in the frequency of C4 null alleles and suggested that all the reported HLA alleles could reflect association with a limited number of ancestral haplotypes (AHs). On this occasion, we studied 122 Caucasoid patients classified according to Centers for Disease Control (CDC) criteria. The control group consisted of 67 seronegative homosexual or bisexual males at risk of developing HIV infection. C4 null alleles were unequivocally present in 58% of patients in CDC IV compared with 33% of the seronegative subjects (chi 2 = 5.65, p less than 0.05). Furthermore, C4 null alleles could be excluded in only 8% and 16% of CDC III and IV, respectively, but in 30% of the seronegative subjects. An increased frequency of three AHs largely accounted for the increases in C4 null and HLA alleles. To examine the role of specific AHs we undertook a longitudinal analysis of a subgroup of 26 patients who seroconverted under observation. Seventeen of these patients were followed for 32 to 63 months. All seven patients with the 8.1 AH (A1, CW7, B8, BfS, C4AQ0, C4B1, DR3, DQ2) developed low CD4 lymphocyte counts (less than 450 x 10(6)/l) compared with only 2 of 10 patients without this haplotype (p less than 0.002). All three deaths occurred in patients with the 8.1 AH. The acquired immunodeficiency syndrome developed in three further cases with either 8.1- or B35-bearing (35.x) haplotypes. Sequential CD4/8 ratios showed an early and progressive decline in individuals with 8.1 or 35.x. Since the 8.1 and 35.x AHs contain deletions of the central major histocompatibility complex (MHC) genes, we suggest that the genes affecting HIV infection and progression are within the central MHC region.

The relationship between HLA-DR3 and T-cell regulation of immunoglobulin production in primary sclerosing cholangitis

Immunoglobulin production in vitro, its control by concanavalin A-activated suppressor T-cells, and the relationship between abnormalities in nonantigen-specific suppression and histocompatibility antigens have been studied in 20 patients with primary sclerosing cholangitis (PSC). Suppression of IgG, IgM, and IgA synthesis was impaired in 12 patients with PSC alone, but was normal in 8 with PSC and associated ulcerative colitis (UC). The HLA antigens B8 and DR3 were increased in frequency in both groups of patients, but an association between DR3, and to a lesser extent B8, and defective suppressor T-cell function was only observed in the patients with PSC alone. These results not only provide further evidence of an association between HLA DR3 and impaired nonantigen-specific suppression but also indicate the genetic complexity of this association and its specificity, being found in this study in only one subgroup of patients with PSC.

Myasthenia gravis associated with multiple sclerosis. Epidemiological survey and immunological findings

Patient registers on myasthenia gravis (94 patients) and multiple sclerosis (991 patients) from a population of 1.5 million were reviewed to find patients with both diseases. Seven potential candidates were found, but both diagnoses were confirmed in 2 women only. The first patient had also iritis, the second patient had, besides MG and MS, bronchial asthma and polyarthritis. Both neurological diseases had a relatively mild clinical course. Thymectomy relieved MG symptoms in both patients. Cerebrospinal fluid studies during the follow-up indicated immunoactivation within the central nervous system. Changes in cellular immunity were also noted. The HLA types were different. The combination of these two diseases appears to be more common than expected.

An immunogenetic study of suppressor cell activity in autoimmune chronic active hepatitis

Some patients with autoimmune chronic active hepatitis as well as their disease-free first degree relatives show decreased suppressor cell activity of peripheral blood T lymphocytes. Studies were therefore undertaken in families ascertained by the presence of a single chronic active hepatitis patient to determine if this abnormality of immune regulation represents a genetic phenotype simply controlled by a gene or genes at a putative disease susceptibility locus and, further, if this locus showed linkage to either the HLA or the immunoglobulin constant region loci. In addition to determining circulating autoantibody status and genotyping for HLA and immunoglobulin allotypes, suppressor T cells were evaluated by surface markers and by determining their ability to suppress IgG secretion in vitro. The results suggest that immunoregulatory dysfunction in autoimmune chronic active hepatitis is a familial abnormality, but that this abnormality occurs independent of circulating autoantibody status and of the segregation of genes for HLA or immunoglobulin allotypes.

An analysis of autoimmunity through studies of DNA antibody idiotypes

The existence of idiotypic networks, first postulated over 12 years ago, is now widely recognised. Idiotypic analyses of autoantibodies have been reported among both hybridoma-derived and naturally occurring immunoglobulins. In this review the many studies of idiotypes detected on anti-DNA antibodies, notably one designated 16/6, are analysed to see what clues they offer to our understanding of autoimmunity. The links between infection and autoimmunity are emphasised by this analysis. It is also obvious that idiotypes first identified an autoantibodies are not confined to these immunoglobulins. Thus, the 16/6 idiotype originally described on a hybridoma-derived monoclonal anti-DNA antibody has also been identified on naturally occurring antibodies binding the Klebsiella polysaccharide K30.

Nicotine induces T-suppressor cells: modulation by the nicotinic antagonist D-tubocurarine and myasthenic serum

To further unravel the basic immunoregulatory defect present in myasthenia gravis, we undertook to study nicotinic acetylcholine receptor (AchR) activity on human peripheral blood leukocytes. A biphasic suppressive effect of nicotine was observed on lymphocyte proliferative responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen with peaks at 10(-9) and 10(-5) M. Using a coculture approach, T cells preincubated with nicotine for 24 hr showed enhanced suppressor cell activity. This was partially blocked by serum from myasthenic patients and by the nicotinic antagonist d-tubocurarine. These studies suggest that suppressor T lymphocytes bear functional nicotinic AchR, which may be modulated by myasthenic serum, with possible relevance to the pathogenesis of myasthenia gravis.

Association of HLA DR1 with high D-penicillamine binding to monocytes in females

Binding of D-Penicillamine (D-Pen) to human monocytes was examined by flow cytometry with fluorescent D-Pen conjugate. Cells from HLA DR1-positive healthy females bound significantly more D-Pen than cells from DR1-negative healthy females (P = 0.015), and DR1 was associated with the highest binding among HLA DR antigens. In contrast, DR4 was associated with the lowest binding in healthy females. A difference in D-Pen binding between healthy females who were DR1-positive, DR4-negative and those who were DR1-negative, DR4-positive was statistically significant (P = 0.026). Neither healthy females nor healthy males showed significant associations of D-Pen binding with HLA A, B, or C antigens, nor did healthy males show an association between strength of D-Pen binding and any DR antigens.

Rearrangement of 21-hydroxylase genes in disease-associated MHC supratypes

Human cDNA probes for 21-hydroxylase (21-OH) and for complement component C4 are used on restriction digests of the members of several families with interesting supratypes. The presence of two Taq I fragments of 3.7 kb and 3.2 kb in size with a 21-OH probe is confirmed in most individuals who show no evidence of C4 deletions or 21-OH deficiency. Most individuals also show a doublet of weakly hybridizing bands at approximately 2.5 kb, the smaller of which is part of the 21 A gene. The arrangement of the 21-OH genes on disease-associated supratypes was examined, and it is shown that copies of the same supratype from unrelated individuals are usually identical. Evidence is provided for deletions of 21A on the B8, C4AQ0, C4B1, BfS, DR3 and B18, C4A3, C4BQ0, BfF1, DR3 supratypes and a duplication of 21A on the B14, C4A2, C4B1/B2, BfS supratype. Gene rearrangements may be relevant to diseases such as juvenile onset diabetes mellitus.

HLA A1-B8-DR3 and suppressor cell function in first-degree relatives of patients with autoimmune chronic active hepatitis

The relationship between suppressor T cell function and the inheritance of the A1, B8, DR3 haplotype was studied in 17 healthy, first-degree relatives of patients with autoimmune chronic active hepatitis. A marked defect in suppressor cell function was found significantly more often in A1, B8, DR3-positive relatives (5 of 7) compared with those who were A1, B8, DR3-negative (1 of 10; P = 0.017). Less marked abnormalities were also found in the A1, B8, DR3-negative relatives compared with A1, B8, DR3-negative control subjects. The results indicate that the defects in suppressor cell function in patients with untreated chronic active hepatitis result from the inheritance of genetic factors linked to the major histocompatibility complex and other gene loci and are not secondary to hepatic inflammation.

Myasthenia gravis and HLA antigens in American blacks and other races

The association of HLA B8 and DR3 with generalised adult onset myasthenia gravis (GMG) in European Caucasoids is now well established. Studies of the HLA association with myasthenia gravis (MG) in other races might help to determine the location of a critical disease locus. Some previous studies in Japanese, Thais, Asian Indians and Filipinos have been reported. In this study HLA A, B, C and DR typing on 28 American blacks with either GMG or ocular myasthenia gravis (OMG) is reported. A significant increase in both HLA A1 and B8 was detected but there was an increase in DR5 rather than DR3. A review of the HLA antigen frequencies in other races and in D-penicillamine (D-Pen) induced MG suggests that prior claims implicating immune response genes marked by DR3 require review. It seems unlikely that any particular HLA allele is involved directly. Other possibly relevant combinations of alleles or supratypes are suggested. These may provide the basis for future studies of the immunogenetic basis for MG.

T-cell subsets regulating anti-acetylcholine-receptor-antibody formation in myasthenia gravis and characterization of suppressor T-cell factors involved

The in vitro generation of anti-acetylcholine-receptor (AChR)-antibody-forming cells from B cells of myasthenia gravis (MG) patients occurred only in the presence of OKT4+ cells. Anti-AChR-antibody formation by lymphocytes from MG patients was suppressed by normal T cells, and the requirement of both OKT4+ and OKT8+ cells was suggested for this suppression. Culture supernatant from normal T cells stimulated with excess doses of AChR antigen, but not T cells from patients, suppressed anti-AChR-antibody formation by lymphocytes from patients. The fraction of the culture supernatant with molecular weight of 45,000 to 67,000 seemed to contain an AChR-antigen-specific and antigen-binding suppressor factor with some allogeneic barrier, while the fraction with a molecular weight of 10,000 to 28,000 contained the antigen-nonspecific factor.

Autoimmunity in spontaneous myasthenia gravis in dogs

Spontaneous canine myasthenia gravis (MG) mimics the human disease in almost every respect. Both dogs reported here exhibited the autoantibodies characteristic of MG, i.e., anti-acetylcholine receptor (anti-AChR) and antistriational (AStr). Fluctuations in the anti-AChR titer during spontaneous remission and recurrence of MG in one dog provide support for the concept of a symptomatic threshold titer above which anti-AChR must rise before disease signs develop. The increase in the anti-AChR titer and recurrence of disease signs followed vaccination and an infection. Interestingly AStr also reappeared in this dog and serum IgG concentration increased. AStr in the second dog was associated with the presence of a thymoma and had a staining pattern characteristic of human MG.

Complement allotyping in SLE: association with C4A null

Immunogenetic factors are important in systemic lupus erythematosus (SLE) and deficiency of a number of complement components is often associated with a lupus-like illness. The complement components Bf, C2 and C4 are encoded within the human major histocompatibility complex (MHC) and are polymorphic. A study of HLA and Bf and C4 polymorphism in 43 patients with SLE was undertaken firstly, to determine whether partial deficiency of C2 and C4 may predispose to disease and secondly, because it may allow the better definition of important supratypes associated with the disease and which may include the relevant disease gene(s). An increased frequency of C4A null alleles has been shown in SLE, with a minimal estimated C4A null gene frequency of 0.32 versus 0.20, but no case of partial C2 deficiency was identified. These results may indicate a direct role for partial C4 deficiency or that C4A null may be a marker for an important supratype which includes the relevant disease gene(s).

Abnormal immunoregulation in patients with insulin dependent diabetes mellitus and their healthy first degree relatives

Autoantibodies, cell-mediated autoimmunity, and impaired suppressor T cell function, suggesting abnormal immunoregulation, have been implicated in the pathogenesis of juvenile-onset insulin dependent diabetes mellitus (IDDM). To examine one of the parameters of immunoregulation, and to explore its relationship to the disease, we tested suppressor cell function in IDDM patients, their clinically healthy relatives, and in normal unrelated controls. 9/15 IDDM had impaired suppressor cell function compared to 1/8 age-matched healthy sibs (p less than 0.04) and to 0/9 unrelated controls (p less than 0.005). There was no correlation between abnormal suppressor cell function and the patient's age, sex, preprandial blood glucose levels, age at the time of diagnosis, or duration of the disease. However, there was a trend for a higher proportion of HLA Dr3 positive diabetics to have abnormal suppressor cell function compared to DR3 negative patients. Impaired suppressor cell function was also found in 5/23 clinically healthy first degree relatives; 4/5 were related to a diabetic who demonstrated abnormal suppressor cell function. These findings raise the possibility that underlying familial, probably genetically determined abnormalities in immunoregulation, acting in concert with other environmental or genetic factors, may contribute to disease susceptibility in IDDM.

Primary immunoglobulin deficiency and haematological disorders

Nine patients with immunoglobulin deficiency and various haematological disorders are presented. In all patients, recurrent infections had antedated the onset of the haematological disorder but, in most, the possibility of primary immunodeficiency had not been considered until after the haematological diagnosis had been established. The recognition of immunodeficiency is important since such patients may require steroids, immunosuppressive therapy or splenectomy. Gammaglobulin would appear to be the appropriate therapy in this situation. Infections were reduced in all 6 patients so treated.

Disease associations with complotypes, supratypes and haplotypes

We have used the term supratype to describe combinations of alleles and have examined associations with disease. In RA and insulin-dependent diabetes one or more supratypes appear to be important but their functional significance remains obscure. In MG and SLE the HLA supratype may contain loci involved in immunoregulation, complement synthesis and hormone metabolism. MG induced by D-Pen is associated with Bw35/DR1 rather than A1, B8, DR3. In contrast there is no evidence of a supratype in AS. We have proposed a model for the pathogenesis of sacroiliitis and AS and have postulated two non-linked genes which act stepwise upon HLA-B27. There are cogent reasons for examining the functional effects of known loci within the MHC and particularly those involved in the expression of complement components.

HLA antigens and acetylcholine receptor antibodies in penicillamine induced myasthenia gravis

Antibodies to the acetylcholine receptor and HLA antigens have been studied in patients with myasthenia gravis occurring in association with penicillamine treatment. The properties of the antiacetylcholine receptor in these patients differed from those in patients with idiopathic myasthenia gravis in terms of specificity and affinity. These patients had an increased prevalence of HLA Bw35 and DR1 compared to controls and a decreased frequency of B8 and DR3 compared to patients with idiopathic myasthenia gravis. Likewise, they had a decreased frequency of DR4 compared to patients with rheumatoid arthritis. These data provide supportive evidence for a role for penicillamine in the induction of myasthenia gravis in genetically predisposed individuals.

Immune regulation in myasthenia gravis: evidence for an increased suppressor T-cell population

The production of anti-acetylcholine receptor antibodies in myasthenia gravis represents a persistent and unexplained break in self-tolerance. The studies reported here demonstrate an altered regulatory T-cell population with an increase in the percentage of circulating T-suppressor cells as defined by two independently developed murine monoclonal antibody markers. Leu 2a- and OKT8a-positive cells were significantly increased within the T-cell population in myasthenia gravis (25.0 +/- 6.4% versus 20.7 +/- 2.9% and 34.9 +/- 7.0% versus 26.0 +/- 3.2%, respectively) compared to an age- and sex-equivalent group. In addition, the circulating total T-cell population was reduced in myasthenia gravis. Patients with symptomatically uncontrolled disease (with or without immunosuppression) demonstrated significantly altered ratios of helper to suppressor T-cells, while patients whose myasthenia symptoms were controlled did not differ from normal subjects.

Defective mitogenic responses in myasthenia gravis and multiple sclerosis

Using in vitro lymphocyte proliferation induced by the phytomitogen concanavalin A (Con A), we investigated immune function and regulation in patients with myasthenia gravis (MG) and multiple sclerosis (MS). Unfractionated peripheral blood mononuclear cells of normal individuals responded to a wide range of ConA concentrations; the T cell fraction responded to a lesser degree and only to high concentrations. These findings suggest the presence of two receptors for ConA, one of high affinity present on a non-T cell accessory cell and the other of low affinity present on T cells. Contrasting defects in the level of response of unfractionated lymphocytes and T cells were found in patients with MG and MS. The peak response of T cells in the MG patients was 22.6 +/- 9.6 X 10(3) cpm (mean +/- SEM) compared with 54.6 +/- 6.5 X 10(3) for controls (p less than 0.05), while the response of unfractionated lymphocytes did not differ from that in controls. For MS patients, the unfractionated lymphocyte response was diminished: 56.3 +/-2.8 X 10(3) cpm versus 70.5 +/- 4.5 X 10(3) for controls (p less than 0.05), while the T cell response was normal. These results indicate a defect in the direct T cell response in MG; in contract, in MS the response requiring T cell-accessory cell interaction is abnormal.

Suppressor cell activity and beta-cell function in insulin-dependent diabetics

Immunological mechanisms may play a role in the pathogenesis of insulin-dependent diabetes mellitus (IDDM), and suppressor cell activity (SCA) has been found depressed at diagnosis. The aim of the present study was to elucidate whether patients with preserved beta-cell function display a different SCA than other patients. Sixteen patients without and 12 patients with beta-cell function after averagely 9 years' duration of IDDM were examined. The suppressive effect of lymphocytes was investigated after incubation with concanavalin A followed by inactivation. Suppression was measured as the ability of the lymphocytes to inhibit 3H-thymidine incorporation in concanavalin A stimulated normal donor lymphocytes. The main findings were: (1) No significant differences in SCA between patients with and without beta-cell function, and one of these patient groups had SCA significantly different from normal controls. (2) A correlation between SCA and administered dose of insulin among patients without beta-cell function. It is concluded that the actual SCA several years after diagnosis is not connected with the beta-cell function in patients with IDDM.

Monoclonal antibody analysis of blood T-cell subsets in myasthenia gravis

Analysis of peripheral blood T -cell subsets and B-cells in patients with myasthenia gravis was performed using monoclonal antibodies and antibody against surface immunoglobulins (SIg) in an immunofluorescent technique. We found a modest but significant decrease in percentages of OKT3- and OKT8-positive cells (thought to represent total T-cells and T-suppressor/cytotoxic cells, respectively) in myasthenics as a group. The percentage of OKT3-positive cells was significantly decrease in patients with late-onset disease (greater than 35 years old), while the percentage of OKT8-positive cells was significantly reduced in those with early-onset myasthenia (greater than 35 years old). Both thymectomized and nonthymectomized patients exhibited a decreased percentage of OKT3-positive cells. No significant difference was found between the percentages of SIg-positive cells in myasthenics and controls. Our results suggest that only modest imbalances of circulating immunoregulatory lymphocytes occur in myasthenia gravis; however, it is conceivable that the small differences observed in this study may reflect pathogenetically important reductions in a functionally distinct lymphocyte subpopulation.

A "spontaneous" cold-reactive IgM antibody with anti HLA-B8 specificity in a patient with multiple sclerosis

A case of a 35-year-old female with multiple sclerosis is reported who developed without apparent prior sensitization a lymphocytotoxic antibody with anti-HLA-B8 specificity. The antibody persisted for several years with the same titer. The cytotoxic activity of the patient's serum was contained within the IgM fraction. The antibody reacted optimally at low temperature, exclusively against lymphocytes homozygous for HLA-B8. In B8-heterozygous cells, cytotoxic reactions were obtained only following enzymatic pretreatment. The antibody's binding avidity was weak; for its complete absorption, many times more B8-positive lymphocytes or platelets were needed than for a "normal" anti-B8 antibody of the same titer. In HLA redistribution and blocking experiments, it was demonstrated that the antigenic determinant recognized by this antibody is carried by the B8 molecule. It is unclear whether "spontaneously" occurring cold-reactive IgM antibodies with HLA specificity are induced by viral agents or whether they reflect "spontaneous" clonal lymphocyte proliferation.

HLA-and Gm-linked genes affecting the degradation rate of antigens (sheep red blood cells) endocytized by macrophages

Phagocytosis and catabolism of sheep red blood cells by human peripheral blood phagocytes were studied in 100 normal caucasoid subjects (44 males and 56 females). Both phenomena are highly reproducible, and their indices seem to be biological constants. There is no correlation between these two indices and the indices do not have a correlation with ABO or Rh markers. Further, the phagocytic index has no correlation with HLA and GM markers. However, a low speed of degradation is significantly correlated (p = 0.001) with the HLA-DR3 antigen, and most of the low degraders are significantly correlated (p = 0.006) with both DR3 and Gm 3,23,11 (probably Gm homozygous). Thus the gradient of antigen degradation could be related to an interaction between MHC and Gm immunoglobulin genes, as is found in the mouse [Biozzi's high (H) and low (L) responder strains.

Lymphocyte studies in rheumatoid arthritis. V. Suppressor cell function in peripheral blood

Peripheral blood lymphocytes from 30 patients with rheumatoid arthritis and 14 controls were examined for suppressor activity by two different assays. These were the Concanavalin-A-induced and the short-lived suppressor cell assays. There was no difference in suppressor activity between patients and controls, the suppressor activity of HLA-DR3 positive patients was no less than that of non-DR3 patients. However, patients with nodules showed reduced suppression in the short-lived suppressor cell assay when compared with patients without nodules.

Lymphocytotoxins in rheumatoid arthritis: prevalence, lymphocyte specificity, and HLA-DR antigens

37% (57/155) of sera from patients with rheumatoid arthritis contain cold-reacting lymphocytotoxic antibodies. Lymphocytotoxins were predominantly of the weakly reactive type and were more likely to be present in patients who were HLA-DR4 positive. By contrast, patients who were HLA-DR3 positive were more likely to have strongly reactive lymphocytotoxins. The lymphocyte subclass reactivity of the lymphocytotoxins was: 67% versus B lymphocytes, 27% against both T and B cells, and 7% for T cells.

Myasthenia gravis. A survey

Myasthenia gravis is a chronic disease characterized by a fluctuating weakness of voluntary muscle, with a preference for the muscles innervated by cranial nerves. The pathophysiological mechanism is a loss of postsynaptic acetylcholine receptors to less than 20-30% so that the safety margin of neuromuscular transmission is lost. It is probable that the function of the remaining acetylcholine receptors is impaired by antibodies against receptor proteïn, which can be demonstrated in the serum in 80-90% of the patients, and which are highly specific for the disease. An experimental autoimmune myasthenia can be induced in many animal species by immunization with purified receptor proteïn and this disease is remarkably similar to the human myasthenia with exception of the fluctuating course. The human disease has to be considered as an autoimmune disease, although the initiating mechanism is unknown. The occurrence of tumors of the thymus in 10-15% and the presence of germinal centres in about 70% of the thymus glands removed by operation are highly suggestive of the importance of the thymus in the pathogenesis, but the definite mechanism (harbouring of an abnormal antigen in myoid cells, or/and false instruction of thymocytes with lack of suppressor cells) is essentially unknown. In most patients the disease tends ot have a favourable course from 5-10 years after onset and complete remission occur in about 20% after 10-20 years. Therapy with anticholinesterases, providing an increase in acetylcholine, is of partial benefit in most patients. Thymectomy has an excellent effect in about 30% of the patients without thymoma under the age of 40 during the first three years of the disease, and is of benefit in still another 30-40%. The use of prednisone and immuno-suppressive drugs has improved the prognosis of the 20% of the patients with severe life threatening symptoms, half of whom have a thymoma.

Comparison of antigenic sources for acetylcholine receptor antibody assays in myasthenia gravis

Antibody titers to the acetylcholine receptor (AChR) from patients with myasthenia gravis, in identical serum samples, were directly compared using denervated rat, human, and baboon muscle as the source of AChR antigen for radioimmunoassay (RIA). Calculations were standardized by using binding isotherms for each antigen source and calculating the percentage of AChR sites labeled with [125I]alpha-bungarotoxin at the concentration used in the RIA. In patients with high AChR antibody titers, the antibody concentration when human muscle was used as the antigen source measured up to tenfold higher than that with denervated rat muscle. In patients who had low antibody titers with human muscle antigen, assays using rat denervated muscle AChR frequently failed to demonstrate diagnostically abnormal titers. The data explain difference among several reported series in the percentages of patients with myasthenia gravis who had elevated serum antibody concentrations. AChR antibody concentrations with baboon muscle as the antigen source were comparable to those in which human muscle was used.