An analysis of in vitro B cell immune responsiveness in human lymphatic filariasis

The immunoregulatory mechanisms involved in B cell function in patients with varying clinical manifestations of bancroftian filariasis were examined by studying the ability of peripheral blood mononuclear cells (PBMC) or PBMC subpopulations from patients with elephantiasis, asymptomatic microfilaremia (MF), and acute tropical pulmonary eosinophilia (TPE) to produce polyclonal and parasite-specific antibody in vitro, both spontaneously and in response to a mitogen (PWM) and to parasite antigen. When the spontaneous or mitogen-driven polyclonal responses were examined, all groups produced significant amounts of IgM and IgG; those with TPE produced extremely high levels. However, when in vitro parasite antigen-specific responses were examined, those with MF were unable to produce filaria-specific antibody either spontaneously or in response to PWM or parasite antigen; in contrast, patients with chronic lymphatic obstruction or TPE produced large quantities. Removal of neither adherent cells nor T8+ T cells affected the parasite-specific B cell anergy seen in those with MF. This absent or severely diminished capacity to produce antibody on parasite antigenic stimulation in patients with MF is likely responsible for the low levels of parasite-specific antibody seen in this most common clinical manifestation of bancroftian filariasis. Its inability to be reversed by the removal of "suppressor elements" suggests a state of B cell unresponsiveness to the parasite.

An analysis of in vitro B cell immune responsiveness in human lymphatic filariasis

The immunoregulatory mechanisms involved in B cell function in patients with varying clinical manifestations of bancroftian filariasis were examined by studying the ability of peripheral blood mononuclear cells (PBMC) or PBMC subpopulations from patients with elephantiasis, asymptomatic microfilaremia (MF), and acute tropical pulmonary eosinophilia (TPE) to produce polyclonal and parasite-specific antibody in vitro, both spontaneously and in response to a mitogen (PWM) and to parasite antigen. When the spontaneous or mitogen-driven polyclonal responses were examined, all groups produced significant amounts of IgM and IgG; those with TPE produced extremely high levels. However, when in vitro parasite antigen-specific responses were examined, those with MF were unable to produce filaria-specific antibody either spontaneously or in response to PWM or parasite antigen; in contrast, patients with chronic lymphatic obstruction or TPE produced large quantities. Removal of neither adherent cells nor T8+ T cells affected the parasite-specific B cell anergy seen in those with MF. This absent or severely diminished capacity to produce antibody on parasite antigenic stimulation in patients with MF is likely responsible for the low levels of parasite-specific antibody seen in this most common clinical manifestation of bancroftian filariasis. Its inability to be reversed by the removal of "suppressor elements" suggests a state of B cell unresponsiveness to the parasite.

Circulating parasite antigen(s) in lymphatic filariasis: use of monoclonal antibodies to phosphocholine for immunodiagnosis

Hybridoma cell lines producing monoclonal antibodies (MAb) against a 200 kD antigen found circulating in the sera of microfilaremic patients infected with Wuchereria bancrofti were obtained by immunizing mice with a partially purified antigen preparation. A sensitive MAb (CA101)-based ELISA for measuring circulating parasite antigen was capable of detecting antigen in the sera of 93% of patients with microfilaremia, 46% of those with lymphatic obstruction, and 56% of patients with tropical pulmonary eosinophilia syndrome. Circulating antigen was absent from sera of normal controls, and "false positives" were recorded in only two of 17 patients with nonfilarial helminth infections. By ELISA and immunoblot analysis, it was shown that three of the monoclonals raised to this 200 kD antigen were directed to epitopes of phosphocholine (PC). Two MAb (CA86, CA101) were identified as having the T15 idiotype previously associated with antibodies to the PC of pneumococcal teichoic acid; one was untypeable. All three of these anti-PC MAb reacted with adult, microfilaria, and larval antigen preparations, and by immunoblotting showed multiple banding patterns that indicated the presence of PC determinants on many different antigenic molecules. On the other hand, target antigens of CA101 which were found in the circulation of infected patients were limited to three species with apparent m.w. of 200, 160, and 78 kD. The 200 kD antigen was seen more frequently than the other two antigens. Other T15 anti-PC MAb derived from mice not immunized with filarial antigen showed similar patterns of reactivity with circulating filarial antigen.

Circulating parasite antigen(s) in lymphatic filariasis: use of monoclonal antibodies to phosphocholine for immunodiagnosis

Hybridoma cell lines producing monoclonal antibodies (MAb) against a 200 kD antigen found circulating in the sera of microfilaremic patients infected with Wuchereria bancrofti were obtained by immunizing mice with a partially purified antigen preparation. A sensitive MAb (CA101)-based ELISA for measuring circulating parasite antigen was capable of detecting antigen in the sera of 93% of patients with microfilaremia, 46% of those with lymphatic obstruction, and 56% of patients with tropical pulmonary eosinophilia syndrome. Circulating antigen was absent from sera of normal controls, and "false positives" were recorded in only two of 17 patients with nonfilarial helminth infections. By ELISA and immunoblot analysis, it was shown that three of the monoclonals raised to this 200 kD antigen were directed to epitopes of phosphocholine (PC). Two MAb (CA86, CA101) were identified as having the T15 idiotype previously associated with antibodies to the PC of pneumococcal teichoic acid; one was untypeable. All three of these anti-PC MAb reacted with adult, microfilaria, and larval antigen preparations, and by immunoblotting showed multiple banding patterns that indicated the presence of PC determinants on many different antigenic molecules. On the other hand, target antigens of CA101 which were found in the circulation of infected patients were limited to three species with apparent m.w. of 200, 160, and 78 kD. The 200 kD antigen was seen more frequently than the other two antigens. Other T15 anti-PC MAb derived from mice not immunized with filarial antigen showed similar patterns of reactivity with circulating filarial antigen.

Persistent thyroid autoimmunity after subacute thyroiditis

Subacute (de Quervain's) thyroiditis (SAT) is accompanied by temporary abnormalities in thyroid function and, in a minority of patients, by transient thyroglobulin and thyroid microsome autoantibody formation. In this report we have examined the sera of patients with SAT for the presence of multiple thyroid autoantibodies using qualitative immunoblotting (Western blotting). For this purpose we used a crude thyroid extract (2,000 g supernatant) as a source of antigen, in order to identify antibodies reacting with a wide range of potential autoantibodies. Eight of the 9 patients tested had autoantibodies which reacted with between 2-18 antigenic determinants (molecular weights 177-10 kd) present in the thyroid antigen preparation. None of the sera reacted with thyroglobulin or thyroid microsomes. The majority of these autoantibodies were directed against antigens which were absent from liver membrane preparations. Furthermore there was no diminution in the levels of these autoantibodies over a period of up to 39 months after the onset of SAT. The prolonged presence of these novel thyroid autoantibodies may explain the recent findings of subtle thyroid defects, such as altered gland iodine content, long after apparent clinical resolution of SAT. The accumulated evidence for a viral aetiology in this condition suggests that these sequelae may be due to a virally-induced autoimmune response.

Parasite-specific anergy in human filariasis. Insights after analysis of parasite antigen-driven lymphokine production

The antigen-specific immune unresponsiveness seen in bancroftian filariasis was studied by examining lymphokine production in peripheral blood mononuclear cells (PBMC) or PBMC subpopulations from 10 patients with asymptomatic microfilaremia, 13 patients with elephantiasis and 6 normal North Americans. In each group of patients, the kinetics of the lymphokine response and the response to mitogens and nonparasite antigens did not differ significantly. In marked contrast, when antigen-induced lymphokine production was examined, most patients with microfilaremia were unable to produce either interleukin 2 (IL-2) or gamma-interferon (i.e., were nonresponders), and the few who could (hyporesponders, generally with quite low microfilaremia levels) did so at levels significantly less than those of patients with elephantiasis, all of whom showed strong responses to parasite antigen. Removal of neither adherent cells or T8+ cells affected the parasite-specific anergy seen in those with microfilaremia, suggesting a state of T cell tolerance to the parasite in patients with this most common clinical manifestation of bancroftian filariasis.

Antibodies to porcine eye muscle in patients with Graves' ophthalmopathy: identification of serum immunoglobulins directed against unique determinants by immunoblotting and enzyme-linked immunosorbent assay

The immunological mechanisms involved in Graves' ophthalmopathy are not known. To explore the pathophysiology of this disorder, we used an enzyme-linked immunosorbent assay to detect antibodies that bound to the 100,000 X g sediment fraction of porcine eye muscle. Serum from patients with Graves' ophthalmopathy had enhanced immunoglobulin binding to porcine eye muscle compared to serum from control subjects (P less than 0.0001); however, several individual normal serum samples also had elevated binding activity. Incubation of serum from some Graves' patients with skeletal muscle or liver tissue resulted in reduction in immunoglobulin binding to porcine eye muscle. Thyroglobulin and TSH reduced binding only at high concentrations. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed some obvious differences in protein bands between porcine eye muscle and skeletal muscle. Serum from many normal subjects and patients with autoimmune thyroid disease formed bands with skeletal muscle protein fractions on immunoblotting, and no specific bands were found using serum from Graves' ophthalmopathy patients. Immunoblots of Graves' patients' serum after reaction with either porcine skeletal or eye muscle showed no reactivity with thyroglobulin (200K and 320K) or thyroid microsomal antigen (105K). Instead, immunoblots of eye muscle and serum from Graves' patients, with or without eye disease, showed two bands at 64K and 73K, which were shared by serum from normal subjects. In addition, several unique eye muscle determinants were detected in serum from 6 of 13 Graves' disease patients analyzed. These unique bands usually had mol wt of less than 50K, and 5 of the 6 patients whose serum reacted with these determinants had significant ophthalmopathy. Our findings support the presence of potential antigenic differences between eye muscle and skeletal muscle accounting for the immunological specificity of eye muscle as a target in Graves' ophthalmopathy.

Eosinophilia in Southeast Asian refugees: evaluation at a referral center

We determined the cause of persistent eosinophilia in 128 Indochinese refugees for whom initial comprehensive routine screening had failed to yield an explanation. Intestinal parasitism with one or multiple organisms was the cause of eosinophilia in all but six of these patients. Hookworm and Strongyloides stercoralis were among the potentially pathogenic organisms most frequently implicated (55% and 38%, respectively). There was no correlation between the age or sex of the patients and the type of infecting organism. We also confirmed the usefulness of a previously described serological test for diagnosing infection with Strongyloides stercoralis and examined the test's ability to distinguish between infected and noninfected individuals and to determine parasitological cure.

Demonstration by immunoblotting of heterogeneity in the autoantibody response directed against fat cells in Graves' disease

Guinea pig fat cell membranes (FCM) have been widely used in preference to thyroid membranes as a source of TSH receptors to investigate TSH receptor antibodies in Graves' disease, because FCM are ostensibly free of other thyroid antigens. However, by FCM immunoblotting we have found: 8 of 10 normal sera bound to determinants at 38 and 190 kDa; 17 other determinants were recognised by 60% of Graves' or Hashimoto sera and by 20% of normal sera; three determinants at 65-90 kDa were recognised by 5 of 13 Graves' but by none of the normal or Hashimoto sera; and none of the determinants recognised appeared to be related to the TSH receptor.

Loa loa infection in temporary residents of endemic regions: recognition of a hyperresponsive syndrome with characteristic clinical manifestations

Loiasis in residents of endemic areas is generally manifested by microfilaremia, episodic angioedema, periocular migration of adult worms, modest eosinophilia, and variable antibody levels. In 20 temporary residents who acquired loiasis in West Africa, however, the clinical presentations were markedly different. Only three of the 20 had detectable microfilaremia. Furthermore, these patients often showed a state of marked immunological hyperresponsiveness manifested by very high titers of antibody to filariae, increased levels of serum IgE, and profound hypereosinophilia--to levels greater than 3,000/mm3 in 18 of the 20. These patients were also notable for the increased severity, frequency, and pruritic nature of their angioedema. Also, significant complications occurred in seven of the 20; one patient developed endomyocardial fibrosis and six, renal disease after treatment with diethylcarbamazine. Thirteen of the 20 developed subcutaneous nodules; adult parasites were recovered from three of five of these patients who underwent biopsy. All of the patients responded to therapy with diminution of their clinical symptoms and decreases in levels of eosinophils, IgE, and antibody to filariae.

In vitro parasite antigen-induced antibody responses in human helminth infections

Helminth parasites characteristically induce vigorous antibody responses in human infections, but the immunoregulatory mechanisms determining the level of these responses are not at all understood. To investigate these mechanisms, peripheral blood mononuclear cells were obtained from 10 patients with parasitic helminth infections (three with schistosomiasis, three with onchocerciasis, and four with loiasis), along with six normal controls. These cells were then cultured in vitro and the capacity of the cells to respond to a specific parasite antigenic stimulus was examined by measuring the amount of parasite-specific antibody produced. Parasite antigen alone, without exogenous mitogen, induced an IgG anti-parasite antibody response in vitro. Optimal responses were obtained at extremely low antigen concentrations--concentrations at which little if any polyclonal immunoglobulin production occurred. Additionally, the in vitro induction of parasite-specific antibody was antigen dose-dependent, requiring much lower antigen concentrations than those necessary to induce lymphocyte blastogenesis. Antibody production was shown to require the cooperative interaction of B and T cells. These studies demonstrate that in vitro responses to antigens from naturally acquired parasitic infections, like those in individuals postimmunization, can be utilized to dissect the cellular and humoral factors that regulate antibody production to naturally acquired human pathogens.

In vitro parasite antigen-induced antibody responses in human helminth infections

Helminth parasites characteristically induce vigorous antibody responses in human infections, but the immunoregulatory mechanisms determining the level of these responses are not at all understood. To investigate these mechanisms, peripheral blood mononuclear cells were obtained from 10 patients with parasitic helminth infections (three with schistosomiasis, three with onchocerciasis, and four with loiasis), along with six normal controls. These cells were then cultured in vitro and the capacity of the cells to respond to a specific parasite antigenic stimulus was examined by measuring the amount of parasite-specific antibody produced. Parasite antigen alone, without exogenous mitogen, induced an IgG anti-parasite antibody response in vitro. Optimal responses were obtained at extremely low antigen concentrations--concentrations at which little if any polyclonal immunoglobulin production occurred. Additionally, the in vitro induction of parasite-specific antibody was antigen dose-dependent, requiring much lower antigen concentrations than those necessary to induce lymphocyte blastogenesis. Antibody production was shown to require the cooperative interaction of B and T cells. These studies demonstrate that in vitro responses to antigens from naturally acquired parasitic infections, like those in individuals postimmunization, can be utilized to dissect the cellular and humoral factors that regulate antibody production to naturally acquired human pathogens.

Filarial parasite-specific T cell lines: induction of IgE synthesis

The development of T lymphocyte lines and clones of defined specificity has provided an important method for investigating T cell recognition of foreign antigens as well as T cell influence on B cell activity. We described previously a parasite-specific T cell line (TCL) derived from a patient with a naturally acquired filarial infection and elevated levels of serum IgE. The TCL is composed of Leu-3+ helper cells and is maintained independent of exogenous growth factors. In the present study, we used these T cells to investigate their immunoregulatory function on the in vitro IgE response. These parasite-specific T cells can provide isotype-specific help for antigen-induced IgE production by B cells in vitro. Autologous T cells profoundly suppress IgE production in a concentration-dependent manner. Furthermore, soluble factors generated from these filarial-specific TCL after antigen stimulation are able to induce the production of IgE in normal human cells not already synthesizing measurable amounts of IgE in vitro. Partial physicochemical characterization of this factor has shown that it is heat labile, has an m.w. between 10,000 and 30,000 M(r), and is a mannose-rich glycoprotein.

Filarial parasite-specific T cell lines: induction of IgE synthesis

The development of T lymphocyte lines and clones of defined specificity has provided an important method for investigating T cell recognition of foreign antigens as well as T cell influence on B cell activity. We described previously a parasite-specific T cell line (TCL) derived from a patient with a naturally acquired filarial infection and elevated levels of serum IgE. The TCL is composed of Leu-3+ helper cells and is maintained independent of exogenous growth factors. In the present study, we used these T cells to investigate their immunoregulatory function on the in vitro IgE response. These parasite-specific T cells can provide isotype-specific help for antigen-induced IgE production by B cells in vitro. Autologous T cells profoundly suppress IgE production in a concentration-dependent manner. Furthermore, soluble factors generated from these filarial-specific TCL after antigen stimulation are able to induce the production of IgE in normal human cells not already synthesizing measurable amounts of IgE in vitro. Partial physicochemical characterization of this factor has shown that it is heat labile, has an m.w. between 10,000 and 30,000 M(r), and is a mannose-rich glycoprotein.

Differentiation stimuli induce receptors for plasma fibronectin on the human myelomonocytic cell line HL-60

Plasma fibronectin (Fn) induces phagocytosis of C3b-opsonized sheep erythrocytes (EC3b) by human peripheral blood monocytes. However, Fn does not induce erythrophagocytosis of EC3b by human polymorphonuclear leukocytes (PMN), unless the PMN have been exposed to C5a or N-formyl-methionyl-leucyl-phenylalanine. Because of this difference, it is of great interest to examine Fn binding to cells that possess the capacity to differentiate into either granulocytes or monocytes. Hence, we have examined the consequences of Fn binding to the human myelomonocytic cell line, HL-60, both before and after in vitro differentiation of the HL-60, along a monocytoid or a granulocytoid pathway. Fn receptors were not found on undifferentiated HL-60, but several differentiating agents promoted the HL-60 binding of Fn-coated microspheres (Fn-ms). The peak of Fn-ms binding occurred four to five days after the induction of differentiation with dimethylsulfoxide (DMSO), and two days after induction by PMA. In addition, cells that differentiated along either the monocytoid or the granulocytoid pathway showed a marked increase in the phagocytosis of both IgG-coated erythrocytes (EA) and EC3b when they were exposed to Fn. Comparison of the effects of anti-Fn monoclonals on the binding of Fn-ms to the monocytes, PMN, and HL-60 showed that the same monoclonals block Fn-ms-binding and Fn-induced EC3b phagocytosis by all three cell types. Two monoclonal antibodies, M1/70 and A6F10, directed against membrane antigens on PMN and monocytes, inhibited Fn-ms binding. Both also blocked Fn-induced EC3b ingestion by these cells. However, neither antibody blocked Fn-ms binding or EC3b ingestion by differentiated HL-60. We conclude that differentiated HL-60 cells express functionally active Fn receptors, similar to monocytes and activated PMN, which, nonetheless, differ from normal cells in their association with the antigens recognized by M1/70 and A6F10.

IgE production in vitro by peripheral blood mononuclear cells of patients with parasitic helminth infections

Helminth parasites induce production of high levels of IgE antibodies but the immunoregulatory mechanisms determining this IgE biosynthesis are poorly understood. To investigate these mechanisms, peripheral blood mononuclear cells were obtained from six normal controls, six atopic patients and eight patients with parasitic helminth infections (three with schistosomiasis, two with loiasis, three with onchocerciasis). Cells were cultured at 1 X 10(6) cells/ml for 8 days in the presence of media alone or media supplemented with pokeweed mitogen (PWM) or cycloheximide; the supernatant fluids from these cultures were then assayed quantitatively for total and parasite specific IgE and IgG using an avidin-biotin amplified (for IgE) or standard (for IgG) microelisa assay. The geometric mean spontaneous IgE production was markedly elevated in peripheral blood mononuclear cells from parasitized individuals (2,487 pg/ml) when compared to those from atopics (358 pg/ml) or normals (152 pg/ml). Spontaneous IgG synthesis was equivalent in all three groups (range 140-420 ng/ml). PWM did not induce IgE production in any group and in the parasitized group even caused significant suppression of total IgE synthesis. Antigen specific antibody production (both IgE and IgG) paralleled total immunoglobulin synthesis. These findings demonstrate for the first time spontaneously enhanced IgE production in vitro in patients with helminth infections and provide a model system for studying the suppressive and regulatory mechanisms controlling IgE secretion.

Parasite antigen-specific human T cell lines and clones. Major histocompatibility complex restriction and B cell helper function

The development of T lymphocyte lines and clones of defined specificity has become an important method for investigating both T cell recognition of foreign antigens as well as T cell influence on B cells. In the present study, human antigen-specific T cell lines and clones have been derived from a patient with a naturally acquired filarial infection. These T cells are of the helper phenotype (Leu 1+, Leu 2-, Leu 3+) and are independent of exogenous interleukin-2. Furthermore, these T cells have been shown to require both antigen-presenting cells and antigen for optimal proliferation. Helper function mediated by these T cells as manifested by the in vitro induction of parasite-specific antibody was antigen-dose dependent, requiring much lower antigen concentrations than those necessary to induce blastogenesis. More importantly, there is an absolute requirement of the T cell line for HLA-DR histocompatible antigen-presenting cells; clones derived from this T cell line show a more specific DR-related restriction--to only one of the two parental DR haplotypes in antigen stimulated proliferative responses. Such parasite antigen specific human helper T cell lines and clones should prove useful in exploring the fine control of the host response to naturally acquired helminth infections. In addition, these long-term T cell lines and clones can provide a potent tool for examining not only the events involved in human T cell responses to parasite antigens, but also into the associated cellular and humoral factors necessary for the B cell responses which follow.

Intradermal hepatitis B virus vaccine: immunogenicity and side-effects in adults

Fourteen adult volunteers were given a series of three 0.1 ml (2.0 micrograms of antigen protein) intradermal doses of hepatitis B virus vaccine (Merck). An antibody (anti-HBs) response was induced in 10 of 12 (83%) who were antibody negative at the start of the study. Two participants who had anti-HBs before vaccination had a significant increase in serum antibody. The two participants with no antibody response were the oldest members of the study group. Side-effects of the vaccine were limited to local reactions at the site of administration.

Lymphokine-mediated suppression of chondrocyte glycosaminoglycan and protein synthesis

Spontaneously released and T cell mitogen augmented lymphokine produced by human mononuclear cells has been shown to induce a concentration dependent reversible suppression of chondrocyte glycosaminoglycan and protein synthesis without significantly enhancing chondrocyte catabolic activity. The modulatory factor(s) is of T cell origin and is trypsin, pronase, and heat sensitive. Prostaglandin inhibitors failed to influence factor formation or activity. Although eluting from Sephadex G-100 over a wide range, peak activity had an approximate molecular weight of 53,000 and appeared distinct from recognized forms of lymphotoxin.