Antigenic heterogeneity of leukemia

When reassessing the clonal origin of malignant tumors, it is argued that most malignant tumors are heterogeneous for a number of phenotypic characteristics including antigenicity. Taking the murine AkR leukemia as an example, how antigenic heterogeneity may affect immunologic approaches to diagnostics and treatment of leukemias is discussed. The consequences for use of monoclonal antibodies in relation to human leukemias are also discussed, especially in light of recent achievements in producing human monoclonal antibodies.     

Antigenic relationships among thermophilic actinomycetes.

Antigens from Micropolyspora faeni, Saccharomonospora viridis, Thermoactinomyces candidus, T. sacchari and T. vulgaris were prepared by growing them on dialysate of trypticase soy broth. Sera from rabbits immunized with these antigens were used to study cross-reactivity between thermophilic actinomycetes by antigen-antibody crossed immunoelectrophoresis and by agar gel double diffusion. Mi. faeni and S. viridis showed some degree of cross-reaction, but both failed to show any cross reactivity with Thermoactinomyces species. Antigens from Thermoactinomyces cross-reacted with members within the genus, but no reactivity against S. viridis or M. faeni antisera was detected. Hence, the presence of antibodies to several thermophilic actinomycetes in the sera of patients may be attributed to the exposure of the individual to different thermophilic actinomycetes rather than to the antigenic cross-reactivity between the organisms.     

Antigenic relationships between chloroplast and cytosolic fructose-1,6-bisphosphatases.

Cytosolic fructose-1,6-biphosphatases (FBPase, EC 3.1.3.11) from pea (Pisum sativum L. cv Lincoln) and spinach (Spinacia oleracea L. cv Winter Giant) did not cross-react by double immunodiffusion and western blotting with either of the antisera raised against the chloroplast enzyme of both species; similarly, pea and spinach chloroplast FBPases did not react with the spinach cytosolic FBPase antiserum. On the other hand, spinach and pea chloroplast FBPases showed strong cross-reactions against the antisera to chloroplast FBPases, in the same way that the pea and spinach cytosolic enzymes displayed good cross-reactions against the antiserum to spinach cytosolic FBPase. Crude extracts from spinach and pea leaves, as well as the corresponding purified chloroplast enzymes, showed by western blotting only one band (44 and 43 kD, respectively) in reaction with either of the antisera against the chloroplast enzymes. A unique fraction of molecular mass 38 kD appeared when either of the crude extracts or the purified spinach cytosolic FBPase were analyzed against the spinach cytosolic FBPase antiserum. These molecular sizes are in accordance with those reported for the subunits of the photosynthetic and gluconeogenic FBPases. Chloroplast and cytosolic FBPases underwent increasing inactivation when increasing concentrations of chloroplast or cytosolic anti-FBPase immunoglobulin G (IgG), respectively, were added to the reaction mixture. However, inactivations were not observed when the photosynthetic enzyme was incubated with the IgG to cytosolic FBPase, or vice versa. Quantitative results obtained by enzyme-linked immunosorbent assays (ELISA) showed 77% common antigenic determinants between the two chloroplast enzymes when tested against the spinach photosynthetic FBPase antiserum, which shifted to 64% when assayed against the pea antiserum. In contrast, common antigenic determinats between the spinach cytosolic FBPase and the two chloroplast enzymes were less than 10% when the ELISA test was carried out with either of the photosynthetic FBPase antisera, and only 5% when the assay was performed with the antiserum to the spinach cytosolic FBPase. These results were supported by sequencing data: the deduced amino acid sequence of a chloroplast FBPase clone isolated from a pea cDNA library indicated a 39,253 molecular weight protein, with a homology of 85% with the spinach chloroplast FBPase but only 48.5% with the cytosolic enzyme from spinach.     

Antigenic heterogeneity in patients with reactions in borderline leprosy.

Fifteen patients with borderline leprosy who developed "reversal" reactions were studied from the inception of treatment. Thirteen showed an appreciable increase in lymphocyte transformation (LT) when preparations of Mycobacterium leprae were used as antigen. The LT responses to either "whole" or "sonicated" preparations of the bacillus in these 15 patients and in nine others also in reaction correlated with the clinical presentation. Those with skin disease predominating in the reaction showed an appreciable increase in LT when whole M leprae was used as antigen. Those with nerve disease predominating showed an increase with sonicated M leprae. In those with both skin and nerve disease there was an increase with both antigen preparations. The ratios of the LT test results (whole to sonicated M leprae) showed highly significant differences between the three groups.     

Antigenic and genomic relationships among turkey and bovine enteric coronaviruses.

Antigenic and genomic relationships among tissue culture-adapted turkey enteric coronavirus (TCV) isolates, three strains of avian infectious bronchitis virus (IBV), and mammalian coronaviruses were investigated. Immunoblotting and immunoprecipitation experiments using polyclonal antisera showed that the four major structural proteins of TCV cross-reacted with the four homologous proteins of bovine enteric coronavirus (BCV), the N and M proteins of mouse hepatitis virus serotype 3, and the N protein of IBV. Close antigenic relationships between TCV and BCV were also established by seroneutralization and hemagglutination-inhibition. Of 49 monoclonal antibodies produced against either TCV or BCV, 11 differentiated the two viruses. Five of these monoclonal antibodies had neutralizing activities and were directed to either the peplomeric S (gp200-gp100) or hemagglutinin HE (gp140-gp65) glycoproteins. BCV cDNA probes tested on purified viral preparations and coronavirus-positive (by electron microscopy) fecal samples from diarrheic turkey poults confirmed the relatedness of TCV and BCV. The two viruses produced distinct cytopathic changes in HRT-18 cells in the presence of trypsin, whereas only TCV isolates were able to reproduce the clinical symptoms in turkey poults. Their matrix (M) proteins undergo different glycosylation processes.     

Antigenic mosaic of Methanogenium spp.: analysis with poly- and monoclonal antibody probes.

Eight well-characterized Methanogenium strains, including the six described type strains, were analyzed with poly- and monoclonal antibody probes to examine the antigenic mosaic of the genus. The pattern of cross-reactions showed that the mosaic is complex and varies with the strains; thus, these organisms have developed a considerable antigenic diversity, which is expressed in their envelopes. Every strain shared at least one determinant with at least one other strain, demonstrating the antigenic cohesiveness of the group. This finding, together with the fact that most strains displayed a distinctive antigenic fingerprint (notwithstanding the limited number of probes available), emphasizes the potential of antibodies for rapid identification of new isolates and for direct elucidation of Methanogenium strains in microbial mixtures.     

Antigenic, molecular and functional heterogeneity of Clara cell secretory proteins in the rat

In an earlier publication we had reported the preparation of a rabbit antiserum specific for rat Clara cell secretory proteins. This rabbit anti-rat Clara cell serum was found to react with two proteins in rat lung lavage by crossed-immunoelectrophoresis. Immunoblotting of rat lung lavage proteins, after sodium dodecylsulphate (SDS) polyacrylamide gel electrophoresis, disclosed three bands of reactivity with anti-Clara cell serum. The relative molecular masses of these three proteins were about 200 (protein A) 55 (protein B) and about 12 kDa (protein C). Anti-Clara cell antibodies eluted from Sepharose-4B-linked protein C (as well as the antiserum raised by immunizing rabbits with protein C) reacted with proteins A and C. Anti-Clara cell antiserum unbound to proteins A and C (as well as antiserum raised by immunizing rabbits with protein B) reacted with protein B only. In non-SDS polyacrylamide gel electrophoresis, protein B migrated as a single band, slightly cathodic to albumin; protein C resolved into three bands, all anodic to albumin. Immunoblots of isoelectric focusing gels showed three bands (pI 5.2-5.7) that reacted with antibody to protein C, and four bands corresponding to protein B were seen in the pI range 4.6-5.0. As determined by immunoperoxidase staining of paraformaldehyde fixed methacrylate embedded 1 micron thick sections of rat lung, protein(s) A (and protein C) and protein B were present in the same cells and in the same granules. Protein B was resistant to trypsin digestion, whereas proteins A and C were readily degraded by trypsin. Rat Clara cell secretory proteins consist of at least two antigenic types that appear to be functionally distinct, and each antigenic type displays charge microheterogeneity.