Evidence that macrophages are programmed to die after activating autologous, cloned, antigen-specific, CD4+ T cells

The bone marrow produces large numbers of monocytes daily, but the mechanisms balancing production and elimination are unknown. In this report we demonstrate that macrophages (M phi) undergo apoptosis after activating autologous CD4+ cells. Since apoptosis is a genetically programmed response, these results argue that M phi death can be part of a normal immune response. This event may have relevance to monocyte/M phi homeostasis, as well as immune response regulation and host defenses to intracellular organisms.

Immunofixation to quantify beta 2-transferrin in cerebrospinal fluid to detect leakage of cerebrospinal fluid from skull injury

beta 2-Transferrin, the desialated form of transferrin normally found only in cerebrospinal fluid (CSF) and aqueous and vitreous humor, is detected by high-resolution immunofixation (IFE). It is not normally found in nasal or aural fluids, saliva, tears, or serum. Detection in nasal fluid has been suggested to document CSF leakage into the nose after skull injury. We measured beta 2-transferrin in 48 samples of CSF. IFE of the CSF was performed on high-resolution agarose gels and stained with Coomassie Blue. beta 2-Transferrin was estimated by quantifying the total transferrin by rate nephelometry and then determining the percentage of transferrin in the beta 2 vs beta 1 region by densitometric scanning of the IFE pattern. We accurately quantified as little beta 2-transferrin as 2.5 mg/L in the CSF samples. The beta 2-transferrin fraction was clearly visible by IFE at concentrations less than 2.5 mg/L, but accurate quantification was difficult. In the samples assayed, the range of beta 2-transferrin was 4.6 +/- 1.9 mg/L. Use of this technique to examine rhinorrhea in a motor-vehicle-accident patient confirmed leakage of CSF into the nasal cavity through a vent in the left olfactory groove.

Antigen processing in the mucosal immune system

The mucosal immune system is concerned with host defense along the moist surfaces of the body which have contact with the external environment. These sites contain specialized lymphoid structures which contain precursors for IgA-synthesizing B lymphocytes and immunoregulatory T lymphocytes which will determine whether oral tolerance or a strong immune response develops against antigens administered orally. The key step to antigen processing in the gastrointestinal tract involves its initial uptake from the gut lumen by specialized follicle associated epithelium called 'M' cells. M cells originate from adjacent crypt epithelium and are interspersed between the absorptive epithelial cells in the follicle-associated epithelium. M cells cells have short, irregular microvilli, are closely associated with lymphocytes, do not have a prominent terminal web, and have only weak alkaline phosphatase activity but strong nonspecific esterase activity. M cells do not express surface MHC class II (HLA-DR) antigens. These cells take up macromolecules, viruses, bacteria and protozoa within 30 minutes from the initial presentation of the antigen to the intestinal lumen. After the initial uptake of antigen by M cells, the antigens are transported into the follicular areas to be processed by dendritic cells and brought into close contact with the antigen-specific precursors for IgA secreting plasma cells. The final result of M cell processing is the production of a vigorous secretory IgA response and local cell-mediated immunity with suppression of a systemic IgG, IgE and delayed-type hypersensitivity to orally-administered antigens.

Secretory immunoglobulin A response to Shiga toxin in rabbits: kinetics of the initial mucosal immune response and inhibition of toxicity in vitro and in vivo

Although the role of Shiga toxin in dysentery is unknown, the toxin is cytotoxic to HeLa cells, causes fluid secretion in rabbit intestine, and is lethal to rabbits and mice when injected parenterally. In the present study, rabbits received three weekly doses of Shiga toxin directly into chronically isolated ileal loops. Within a week, secretions from these loops contained immunoglobulin A (IgA) anti-Shiga toxin. The titer of IgA anti-Shiga toxin increased after weekly doses 2 and 3. Little IgG anti-Shiga toxin was present in loop secretions, although high titers of IgG anti-Shiga toxin were found in the sera. These loop secretions were able to neutralize the cytotoxic effects of Shiga toxin in the HeLa cell assay. The capacity to neutralize the cytotoxicity of the toxin correlated strongly with the IgA anti-Shiga toxin titer in these same secretions. Pooled immune loop secretions were also able to significantly reduce fluid accumulation in acutely ligated loops in rabbits, while loop secretions from control rabbits could not. Shiga toxin elicited a strong secretory IgA response upon application to the intestine. Further, the mucosal antibodies produced functioned to prevent the toxic effects of Shiga toxin both in vitro and in vivo.

Immunoglobulins from the sera of immunologically activated persons with pairs of electrophoretic restricted bands show a greater tendency to aggregate than normal

From in vitro data, it has been speculated that pairs of endogenous restricted bands migrating in close proximity in the gamma region upon high resolution serum electrophoresis (HRE) represent circulating immune complexes (CIC). Using a polyethylene glycol (PEG) method to separate CIC, we found a very high correlation between the presence of such band pairs and elevated levels of CIC (CHI2 = 25.7, p less than 0.001) in 51 sera. HRE appears to be a good screening technique to identify, with a high degree of certainty, samples with elevated levels of CIC for delineation by more specific methods. Yet, examination by gel-filtration chromatography and precipitation with PEG indicated that the molecules comprising the band patterns were not CIC, but polyclonal 7S IgG. These bands are usually found in patients with chronic activation of the immune system. Fractionation of the sera from 5 such patients with various cuts of PEG indicated that the average IgG concentration in the 2.5-5%, and 5-7.5% cuts from patients was 3.99 g/l and 2.2 g/l, while from healthy subjects the concentrations were 0.68 g/l and 2.88 g/l. This reversed precipitation pattern was seen both for absolute levels of IgG and for percent of total IgG. On the average the amount of precipitation of IgG in the 2.5-5% fraction of patients was about 5-fold above that seen in the healthy subjects. The endogenous bands were not associated with any specific cut of PEG, but appeared to be proportionally distributed in accord with the levels of IgG. The data is consistent with the idea that immunologically activated patients exhibit a greater tendency for immunoglobulins to associate than normal. This propensity to aggregate may cause CIC to form in situ in local compartments even though CIC do not appear to be present upon analysis by biochemical techniques.

Reduction of intestinal carcinogen absorption by carcinogen-specific secretory immunity

A secretory immune response to the carcinogen 2-acetylaminofluorene (AAF) was elicited in rabbits by directly immunizing the small intestine with an AAF-cholera toxin conjugate. High-titer, high-affinity secretory immunoglobulin A (IgA) antibody to AAF was secreted into the intestinal lumen in response to this immunogen. Immune secretions reduced the transepithelial absorption of a 125I-labeled derivative of AAF by more than half. This reduction of absorption by hapten-specific IgA suggests that oral vaccines against carcinogens and toxicants could be developed for humans.

Role of M cells in initial antigen uptake and in ulcer formation in the rabbit intestinal loop model of shigellosis

Strains of Shigella flexneri with different invasive and pathogenic potentials were inoculated into the intestinal lumen of acutely ligated loops in nonimmune rabbits. After 90 min, tissues processed for ultrastructural as well as light microscopy showed that the bacilli were phagocytosed by M cells over lymphoid follicles of Peyer's patches and carried in vacuoles into the epithelium. Nonpathogenic as well as pathogenic strains were readily taken up regardless of the presence of the 140-megadalton virulence plasmid. More virulent than avirulent shigellae were found in M cells at 90 min, reflecting replication or preferential uptake of the virulent strains. Heat-killed shigellae of the virulent strain were taken up by M cells to the same degree as the avirulent strains. Incubation of the bacteria for 18 h resulted in surface ulceration which was limited to epithelium overlying lymphoid follicles (M cell areas) in acute loops exposed to the virulent shigellae. Villus epithelium adjacent to the ulcerated follicular domes was intact, although there was mucus depletion. In the present study, we found that pathogenic shigellae appear to replicate in the M cells, escape from the phagocytic vesicles, and thereby initiate the ulcerations in this experimental model of dysentery. While initial antigen processing in the gut for a mucosal immune response may require uptake of luminal microorganisms by M cells, this may pose a threat under some circumstances.

Mucosal IgA elaboration

Secretory IgA is the main immunoglobulin present along mucosal surfaces. It is elicited best by oral rather than parenteral administration of specific antigens. The role of antigen form on the development of a secretory IgA response is still unclear. IgA protects by preventing attachment of microorganisms or their toxic products to the surface epithelium. A wide variety of regulatory T cells are now known to be of considerable importance in optimizing the secretory IgA response. This regulation is at least partly due to the elaboration of small polypeptide products (lymphokines). These lymphokines have been shown to be key signals during the maturation of IgA precursor B cells to IgA-secreting plasma cells. By studying models of the mucosal immune system which closely approximate the natural mucosal immune response, it should be possible to develop vaccines against many pathogenic microorganisms, their toxic products, and to toxicants and carcinogens within the environment.

The enteric immune response to shigella antigens

Mucosal immunity to some enteropathogens occurs naturally following infection. By learning how to optimize initiation of the mucosal immune response it will be possible to develop vaccines against a wide variety of enteropathogens and their toxic products. In the past few years, we have examined stimulation of the mucosal response to Shigella antigens. We have found that the mucosal memory response to Shigella LPS can be stimulated by oral immunization with live, but not with killed Shigella. This primes specific B lymphocytes which, following rechallenge, quickly migrate from the Peyer's patches to mesenteric lymph nodes, the spleen, and back to the Peyer's patches. We have found that the uptake of S. flexneri is the initial step in developing a mucosal immune response to Shigella. Whereas there is little difference between the initial uptake of virulent and avirulent bacteria by M cells, pathogenic strains of Shigella are able to replicate following their uptake by the specialized M cells located in the follicle-associated epithelium of the gut. This likely serves as the source of the ulcerative lesions found in dysentery. Lastly, we have detected a vigorous secretory IgA response to Shiga toxin. The titer of IgA activity to Shiga toxin from these loop secretions correlated well with the ability to prevent Shiga toxin cytotoxin effects in vitro. The extremely vigorous mucosal immune response to Shiga toxin makes this an attractive alternative to cholera toxin to potentiate the secretory IgA immune response.

Strategy to diagnose monoclonal gammopathies in serum: high-resolution electrophoresis, immunofixation, and kappa/lambda quantification

Identification of monoclonal gammopathies in serum has involved electrophoresis of serum proteins, immunoelectrophoresis (IEP), and quantification of IgG, IgA, and IgM. Recent innovations in technology--including high-resolution electrophoresis (HRE), immunofixation (IFX), and quantification of kappa- and lambda-containing immunoglobulins--allow for more rapid and precise assessment of serum for monoclonal proteins. We present a series of guidelines to determine when high-resolution electrophoresis and quantification of immunoglobulins (including kappa and lambda) are sufficient and when additional IFX is required to characterize the monoclonal gammopathy. Of the samples studied, 88% were correctly diagnosed by HRE with quantification of immunoglobulins and kappa/lambda; only 12% required that IFX be performed. The guidelines allow us to detect monoclonal gammopathies quicker and more efficiently by avoiding redundant IEP or IFX testing. For the vast majority of cases, these guidelines allow for a correct diagnosis within one day. After one year of follow-up since completion of the study, no undetected cases of monoclonal gammopathy have eventuated.

Strategy to diagnose monoclonal gammopathies in serum: high-resolution electrophoresis, immunofixation, and kappa/lambda quantification

Identification of monoclonal gammopathies in serum has involved electrophoresis of serum proteins, immunoelectrophoresis (IEP), and quantification of IgG, IgA, and IgM. Recent innovations in technology--including high-resolution electrophoresis (HRE), immunofixation (IFX), and quantification of kappa- and lambda-containing immunoglobulins--allow for more rapid and precise assessment of serum for monoclonal proteins. We present a series of guidelines to determine when high-resolution electrophoresis and quantification of immunoglobulins (including kappa and lambda) are sufficient and when additional IFX is required to characterize the monoclonal gammopathy. Of the samples studied, 88% were correctly diagnosed by HRE with quantification of immunoglobulins and kappa/lambda; only 12% required that IFX be performed. The guidelines allow us to detect monoclonal gammopathies quicker and more efficiently by avoiding redundant IEP or IFX testing. For the vast majority of cases, these guidelines allow for a correct diagnosis within one day. After one year of follow-up since completion of the study, no undetected cases of monoclonal gammopathy have eventuated.

Autoreactivity and altered immune responses in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a poorly understood condition that is associated with a wide variety of immunologic alterations. Because its pathogenesis is unknown, these immunologic alterations have been investigated with an eye toward unraveling the complex mechanism of injury in the bowels of these patients. There are several lines of evidence suggesting that IBD is related to immunologic events. The histopathology of active disease resembles the Arthus reaction, whereas the presence of antiepithelial cell antibodies is reminiscent of Goodpasture's disease. Antibodies against many microorganisms and autoantibodies to mucosal components are commonly found in these patients. Further, there is a marked increase in plasma cells in the lamina propria of patients with active IBD. It is important to keep these findings in perspective. No studies to date have been able to determine whether the features are entirely primary events, that is, related to the initial damage to the intestinal mucosa. If the surface mucosa is injured by an as-yet-unidentified agent, the immunologic findings in IBD may be secondary events. Nonetheless, the similarity in histopathology of the experimental immunologic models of IBD to the human disease encourages investigators to pursue the etiology of this complex disease.

A rapid and sensitive screening method for the detection of anti-2-acetylaminofluorene immunoglobulins

A method is described in which anti-2-acetylaminofluorene immunoglobulins may be detected using a simple and sensitive screening procedure. The method is based on immunoglobulin binding of an 125I derivatized 2-aminofluorene radiotracer. Tracer binding is not isotype specific, and thus the method is useful for the detection of either IgG or IgA. Competitive binding experiments with the radiotracer were used to determine the specificity of immunoglobulin response by measurement of cross-reactivity with related ligands. This method allows quantitation of the immune response to the carcinogen in serum and other biological fluids (i.e., intestinal secretions).

Oligoclonal bands in cerebrospinal fluids: significance of corresponding bands in serum for diagnosis of multiple sclerosis

Controversy exists regarding the definition of oligoclonal bands in cerebrospinal fluid (CSF) and whether CSF bands with corresponding bands in the serum should be disregarded in the interpretation. Much of this controversy results from not distinguishing between the sensitivities of different techniques used for these studies. Because the combination isoelectric focusing/silver staining is more sensitive than agarose gel electrophoresis/Coomassie Blue staining for detecting weak bands, one would expect to find weak oligoclonal bands in the serum more frequently with the former technique than the latter. Yet, most clinical laboratories use agarose gel electrophoresis for this assay. To investigate the clinical relevance of CSF oligoclonal bands as compared with corresponding bands for serum by electrophoresis on agarose gel, we retrospectively reviewed paired CSF and serum electrophoretograms of 104 patients. We determined that the specificity of the oligoclonal-band test for diagnosis of multiple sclerosis was significantly enhanced by running paired CSF and serum specimens when CSF bands with corresponding serum bands were discounted.

Oligoclonal bands in cerebrospinal fluids: significance of corresponding bands in serum for diagnosis of multiple sclerosis

Controversy exists regarding the definition of oligoclonal bands in cerebrospinal fluid (CSF) and whether CSF bands with corresponding bands in the serum should be disregarded in the interpretation. Much of this controversy results from not distinguishing between the sensitivities of different techniques used for these studies. Because the combination isoelectric focusing/silver staining is more sensitive than agarose gel electrophoresis/Coomassie Blue staining for detecting weak bands, one would expect to find weak oligoclonal bands in the serum more frequently with the former technique than the latter. Yet, most clinical laboratories use agarose gel electrophoresis for this assay. To investigate the clinical relevance of CSF oligoclonal bands as compared with corresponding bands for serum by electrophoresis on agarose gel, we retrospectively reviewed paired CSF and serum electrophoretograms of 104 patients. We determined that the specificity of the oligoclonal-band test for diagnosis of multiple sclerosis was significantly enhanced by running paired CSF and serum specimens when CSF bands with corresponding serum bands were discounted.

Combined parenteral and oral immunization results in an enhanced mucosal immunoglobulin A response to Shigella flexneri

Achieving a vigorous secretory immunoglobulin A (IgA) response in intestinal secretions usually requires multiple doses of antigen given orally, while systemic immunity is more easily attained by parenteral immunization. This study examines the role of combined parenteral and oral immunizations to enhance the early mucosal immune response to an enteropathogen. We have used a chronically isolated intestinal-loop model in rabbits as a probe to monitor kinetically the initial (primary) local immune response to shigella lipopolysaccharide (LPS) following combinations of parenteral immunization intramuscularly (i.m.) and oral stimulation with shigellae. Predictably, effective stimulation of systemic immunity was elicited when heat-killed preparations of Shigella sp. strain X16 were given i.m., as shown by strong serum IgG and weak intestinal IgA activity to shigella LPS. A single oral dose of live Shigella sp. strain X16 given to unprimed rabbits elicited only a typical weak IgA response in intestinal secretions. However, when an i.m. dose of heat-killed shigellae was followed 1 day later by an oral dose of live Shigella sp. strain X16, a hyperstimulation of the early secretory IgA response was elicited, and the response reached levels found previously only after multiple oral administrations of live shigellae. This stimulation did not require the use of an adjuvant. At the same time, the animals receiving this combined oral and i.m. regimen had a lower IgG antishigella LPS activity in serum compared with their response after receiving parenteral antigen in adjuvant alone. These findings indicate that while a dichotomy exists between the systemic and mucosal immune responses, careful orchestration of the stimulatory events can promote a vigorous early local IgA response.

Light chain disease associated with the hyperviscosity syndrome

The hyperviscosity syndrome refers to a group of symptoms and signs related to increased blood viscosity often produced by monoclonal immunoglobulins. It is most frequently associated with Waldenström's macroglobulinemia and, on occasion, with other immunoglobulins that are capable of forming highly polymerized molecules. This article is a report on the first case of pure light chain myeloma associated with the hyperviscosity syndrome. The hyperviscous plasma in this case is secondary to the unusual degree of aggregation of kappa light chain as demonstrated by high-resolution electrophoresis, serum immunofixation, and Sephadex g-200 (Pharmacia, Piscataway, NJ) column chromatography.