Radioimmunoscintigraphy of recurrent, metastatic, or occult colorectal cancer with technetium Tc 99m 88BV59H21-2V67-66 (HumaSPECT-Tc), a totally human monoclonal antibody. Patient management benefit from a phase III multicenter study.

PURPOSE: The study contained herein was undertaken to evaluate the accuracy of radiolabeled human monoclonal antibody, 88BV59H21-2V67-66 (88BV59 or HumaSPECT-Tc), in predicting disease resectability in presurgical subjects with recurrent, metastatic, or occult colorectal carcinoma. METHODS: A total of 219 patients with disease visualized on computed tomographic scan (recurrent or metastatic disease) or with negative or equivocal computed tomographic scan and rising carcinoembryonic antigen serum levels (occult group) received technetium Tc99m-labeled 88BV59 intravenously. Planar and single photon emission computed tomograhic images were obtained 14 to 20 hours postinfusion, before surgery. The ability of computed tomographic and HumaSPECT-Tc imaging to define the extent of disease and to predict resectability was evaluated based on surgical and histopathologic results. RESULTS: In patients with recurrent or metastatic disease (170 evaluable patients), the accuracy of predicting nonresectability of disease was significantly greater (P < 0.001) for HumaSPECT-Tc than for computed tomography (60 vs 29 percent). Computed tomography understaged 41 percent of patients believed to have resectable disease compared with 27 percent for HumaSPECT-Tc (P < 0.001). In occult disease patients (29 computed tomographic and 28 HumaSPECT-Tc evaluable patients), the overall accuracy of predicting resectability/nonresectability was 6 percent for HumaSPECT-Tc compared with 24 percent from computed tomography. Administration of HumaSPECT-Tc had no effect on monoclonal antibody-based in vitro diagnostic assays. Only a single patient demonstrated an anti-antibody response (90 ng/ml) at nine weeks postinfusion. CONCLUSION: HumaSPECT-Tc was more accurate than computed tomography in determining disease resectability in patients with metastatic, recurrent, or occult cancer. The addition of HumaSPECT-Tc imaging can play a significant role in patient management decisions.

Radioimmunoscintigraphy of recurrent, metastatic, or occult colorectal cancer with technetium 99m-labeled totally human monoclonal antibody 88BV59: results of pivotal, phase III multicenter studies.

PURPOSE: To assess the performance and potential clinical impact of a totally human monoclonal antibody, 88BV59 (HumaSPECT) (INTRACEL, Corp, Rockville, MD), in 202 assessable presurgical patients with recurrent, metastatic, or occult colorectal cancer. METHODS: 88BV59, labeled with technetium Tc 99m (99mTc) (HumaSPECT-Tc), was injected intravenously, and planar and single photon emission tomography (SPECT) images were obtained 14 to 20 hours postinjection. Surgical and pathologic verification of tumor were used as the standard against which the performance of HumaSPECT-Tc imaging and computed tomography (CT) analysis were evaluated. RESULTS: All patients entered onto the recurrent disease study had at least one tumor site defined on CT. The sensitivity of HumaSPECT-Tc in those CT-positive patients was 87%. The specificity of HumaSPECT-Tc was 57% compared with 17% for CT and the difference was statistically significant (P < .001). The diagnostic information provided by HumaSPECT-Tc significantly (P < .001) improved the accuracy of the identification of resectable and nonresectable disease over that of CT (80% v 62%). HumaSPECT-Tc scans resulted in a significant (P < .001) reduction versus CT in terms of the proportion of patients understaged (27% v 41%) and overstaged (4% v 26%). In patients with occult disease (increasing carcinoembryonic antigen [CEA] titer, negative diagnostic work-up, negative CT), HumaSPECT-Tc correctly identified disease in 15 of 22 (68%) patients. HumaSPECT-Tc images provided additional clinical data that would have affected patient management decisions in 40 of 202 (19.8%) patients. In 365 patients who received 88BV59, only a single detectable human anti-human antibody (HAHA) response (90 ng/mL) at 9 weeks postinfusion was observed. CONCLUSION: HumaSPECT-Tc can provide important and accurate information about the presence and location of disease in patients with a high clinical suspicion of metastatic or recurrent colorectal cancer and either positive (known disease) or negative (occult disease) CT scans.

Polyclonal activation of the murine immune system by an antibody to IgD. XI. Contribution of membrane IgD cross-linking to the generation of an in vivo polyclonal antibody response.

The injection of mice with a foreign, polyclonal antibody to IgD sequentially induces: 1) activation of B cells by cross-linking of their cell membrane (m) IgD; 2) B cell processing and presentation of the bound anti-IgD antibody to T cells; 3) activation of these T cells; and 4) T-dependent stimulation of B cell differentiation into IgG1 secreting cells. To determine whether the cross-linking of B cell membrane IgD and/or the resulting B cell activation that follows contribute to the generation of the polyclonal IgG1 response, we examined the abilities of three sets of anti-delta mAb or mAb fragments to stimulate polyclonal IgG1 production. Within each set mAb were matched for species and Ig isotypic determinants, but differed in avidity for IgD or in ability to cross-link IgD. In addition, experiments were performed to determine whether the anti-delta mAb had to be foreign to the immunized mouse to stimulate an IgG1 response. Results of these experiments indicate that: 1) recognition of the injected anti-delta antibody as foreign is required for the induction of a polyclonal IgG1 response; 2) the cross-linking of B cell membrane Ig, which directly activates B cells, can contribute considerably to the generation of in vivo IgG1 production; and 3) that even relatively weak cross-linking of membrane Ig by ligands that bind it with low avidity can make this contribution.

Polyclonal activation of the murine immune system by an antibody to IgD. X. Evidence that the precursors of IgG1-secreting cells are newly generated membrane IgD+B cells rather than the B cells that are initially activated by anti-IgD antibody.

Injection of BALB/c mice with an affinity-purified goat antibody to mouse IgD (GaM delta) stimulates T cell-independent B cell activation as well as later T cell activation. Activated T cells then induce polyclonal differentiation of B cells into IgG1-secreting cells, which results in an approximately 100-fold increase in serum IgG1 level. It is not known whether the same B cells that are initially activated by GaM delta are the progenitors of the IgG1-secreting cells. To investigate this issue a system was developed in which CB20 mice, which are congenic to BALB/c mice but express Ig of the beta allotype rather than the BALB/c alpha allotype, were injected with GaM delta and simultaneously or subsequently also received BALB/c B cells. The IgG1 response generated by the donor BALB/c B cells was quantitated by an assay specific for IgG1 of the alpha allotype. Our experiments with this system indicate that: 1) BALB/c B cells transferred 2 days after CB20 mice were injected with GaM delta generate a much larger IgG1 response than do BALB/c B cells transferred simultaneously with GaM delta antibody; 2) B cells that express membrane IgD generate the great majority of this response; 3) differences in the magnitudes of the responses of BALB/c B cells transferred at different times after CB20 mice were injected with GaM delta antibody cannot be explained by differences in homing of the donor B cells to the host spleen or by short survival of donor BALB/c B cells after their transfer; and 4) the response made by donor BALB/c B cells transferred 2 days after CB20 mice were injected with GaM delta is proportionate to donor cell representation in the host spleen 1 day after their transfer, whereas the response made by donor cells transferred simultaneously with GaM delta is disproportionately small. These observations suggest that most of the IgG1 antibody made by GaM delta-injected mice is generated by newly produced, mIgD+ B cells that appear approximately 2 days after GaM delta injection, rather than by those B cells that are present in the spleen at the time of GaM delta injection, and support the view that signals that induce B cell secretion of Ig require an interaction with at least partially activated Th cells.

Activation of B cells in vivo by a Fab/Fc fragment of a monoclonal anti-IgD antibody requires an interaction between the antibody fragment and a cellular IgG Fc receptor.

To investigate activation of B lymphocytes in vivo by an interaction between B cell surface Ig (sIg) and an anti-Ig antibody, we compared the abilities of a divalent IgG2b anti-IgD mAb, H delta a/1, and its univalent Fab/Fc fragment to enhance B cell sIa expression in vivo. The Fab/Fc fragment consists of a single Fab linked to Fc, and can interact with C and cellular Fc receptors. Although injection of BALB/c mice with either intact H delta a/1 or H delta a/1 Fab/Fc enhanced splenic B cell sIa expression, Ia expression was enhanced more by intact H delta a/1. Furthermore, injection of mice with 24G2, a mAb to the B cell and macrophage IgG2b Fc receptor, completely blocked the ability of 20 to 500 micrograms of H delta a/1 Fab/Fc to enhance B cell sIa expression, but had no effect on enhancement of B cell sIa expression by 100 micrograms of intact H delta a/1. This effect of 24G2 was mediated by its blocking of IgG2b receptor function rather than simply by its binding to B lymphocytes, since a mAb to the B cell IgE receptor did not interfere with the ability of H delta a/1 Fab/Fc to enhance B cell sIa expression. The different effects of 24G2 on B cell activation by intact H delta a/1 and H delta a/1 Fab/Fc were not a result of differences in the abilities of the intact antibody and its Fab/Fc fragment to activate B cells, since 24G2 did not interfere with the ability of AMS-15, a IgG2a anti-IgD mAb, to slightly increase B cell sIa expression. These observations indicate that a univalent ligand for B cell sIg can activate B lymphocytes in vivo through an IgGFc-IgGFc receptor-dependent interaction.

Production of BSF-1 during an in vivo, T-dependent immune response.

BSF-1, a cytokine produced by some T lymphocyte tumors, has been shown to act with anti-Ig antibodies to stimulate B lymphocyte proliferation, to independently induce resting B lymphocytes to increase their expression of surface Ia antigen, and to induce some activated B lymphocytes to differentiate into IgG1- or IgE-secreting cells. To determine whether BSF-1 might be secreted by normal lymphoid cells in the course of a physiologic immune response, BALB/c mice were injected with an affinity-purified goat antibody to mouse IgD (GaM delta), which induces the generation of a large, polyclonal T-dependent IgG1 response; 4-hr culture supernatants of spleen cells from these mice were prepared, and these supernatants were assayed for BSF-1 activity by analyzing their ability to induce BALB/c nu/nu spleen cells to increase their expression of cell surface Ia in vitro. Culture supernatants of unfractionated spleen cells removed from mice 4 to 8 days after GaM delta antibody injection induced substantial increases in B lymphocyte surface Ia expression; these increases were blocked by a monoclonal anti-BSF-1 antibody. Culture supernatants of spleen cells from untreated BALB/c mice or from untreated or GaM delta antibody-treated BALB/c nu/nu mice induced small to moderate increases in B cell surface Ia expression, and GaM delta antibody itself induced large increases in B cell surface Ia expression; however, these increases were not significantly blocked by a monoclonal anti-BSF-1 antibody. A culture supernatant of T cell-enriched spleen cells from untreated mice induced small increases in B cell surface Ia expression that were inhibited by anti-BSF-1 antibody, as was the larger increase in B cell Ia expression induced by a culture supernatant of T cell-enriched spleen cells from mice sacrificed 3 days after GaM delta injection. On the other hand, T cell-depleted spleen cells from BALB/c mice injected with GaM delta antibody 7 days before sacrifice failed to generate culture supernatants with BSF-1 activity. Supernatants prepared from spleen cells taken from untreated mice or mice treated with GaM delta antibody 1 to 3 days before sacrifice did not block the ability of purified BSF-1 to induce an increase in B cell surface Ia expression, and thus did not contain inhibitors of BSF-1 activity.(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro and in vivo B lymphocyte-activating properties of monoclonal anti-delta antibodies. I. Determinants of B lymphocyte-activating properties.

To appreciate better the mechanisms by which B lymphocytes are activated by anti-Ig antibodies, we characterized seven monoclonal mouse allo-antibodies to IgD of the a allotype for their isotypes, fine specificities, IgD-cross-linking abilities, avidities, and abilities to activate B cells in vitro and in vivo. Three of the monoclonal antibodies tested bound to the Fc fragment of IgD with relatively high avidity and were effective at cross-linking IgD, since they precipitated soluble IgD and rapidly capped B cell membrane IgD. These were the only antibodies tested that induced B cell DNA synthesis in vitro and were the most effective antibodies at inducing in vivo increases in B cell size and DNA synthesis and in vitro and in vivo increases in B cell surface Ia expression. Two antibodies bound to the Fd fragment of IgD with relatively high avidity but could not rapidly cap cell membrane IgD or precipitate soluble IgD even in the presence of 2% polyethylene glycol. These high-avidity, poorly cross-linking antibodies were unable to stimulate B cell DNA synthesis in vitro and were much less effective than the first group of anti-delta antibodies at stimulating in vivo increases in B cell DNA synthesis, size, or surface Ia expression or in vitro increases in surface Ia expression. One antibody, which bound to the Fc fragment of IgD with an intermediate avidity, was unable to rapidly cap B cell membrane IgD or precipitate soluble IgD in saline, but could precipitate soluble IgD in the presence of 2% polyethylene glycol. This antibody failed to induce B cell DNA synthesis in vitro and was as effective as the higher-avidity, poorly cross-linking antibodies at stimulating increases in B cell size, surface Ia expression, and DNA synthesis in vivo, and surface Ia expression in vitro. One antibody, which bound to the Fd fragment of IgD with low avidity and was unable to precipitate soluble IgD or to cap cell membrane IgD, had little ability to activate B cells by any of the parameters studied. Each of the monoclonal anti-delta antibodies, regardless of isotype or fine specificity, when bound to agarose to increase its ability to cross-link IgD, was mitogenic for B cells in vitro. None of the monoclonal antibodies to IgD of the a allotype stimulated B cells from b allotype mice to increase their size, surface Ia expression, or synthesis of DNA in vitro or in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)

Immune response of infants and children to disseminated infections with Neisseria meningitidis.

Acute- and convalescent-phase sera from 34 children and 10 young adults were studied to determine if, at what age, and to which antigens of Neisseria meningitidis they respond during disseminated disease. Seven children older than two years of age who were infected with group C or Y strains developed significant increases in both binding and bactericidal antibody. Children infected with group B strains infrequently (eight [31%] of 26) had measurable increases in serum antibody to this capsular polysaccharide; response was meager when it did occur, was unrelated to age, and was considerably poorer than that of young adults, of whom 80% responded. Convalescent-phase sera from all children contained bactericidal antibody. Binding capacity for group B polysaccharide accounted for only 35% of the bactericidal activity in convalescent-phase sera of children infected with group B strains. Bactericidal antibody in the sera of children who did not respond to capsular polysaccharides was often to a lipooligosaccharide antigen.

IgA blocks IgM and IgG-initiated immune lysis by separate molecular mechanisms.

Circulating IgA which does not bind the first component of complement (C) and does not activate the classical C pathway, blocks the initiation of C-mediated immune effector mechanisms. In at least two clinical situations, epidemic meningococcal disease and severe hepatic dysfunction, IgA blockade of one such mechanism, immune lysis, results in susceptibility to hematogenous bacterial dissemination. The presence of strain-specific IgM, but not IgG, in the sera of susceptibles at the time of dissemination suggested that IgA blockade of IgM-initiated lysis involves a separate mechanism more sensitive to quantitative changes than that involved in IgA blockade of IgG-initiated lysis. We report here that whereas IgA blockade of IgG-initiated immune lysis is a competitive function of the ratio of IgA to IgG, the blocking of IgM-initiated lysis is a noncompetitive function of the ratio of IgA to target cells, independent of the concentration of IgM. In the presence of sufficient IgA to saturate binding sites, IgM is an impotent bystander unable to compete for sites or initiate lysis. Therefore, C-mediated effector mechanisms are more sensitive to quantitative changes in circulating IgA and target cells (binding sites) in the absence of IgG than in its presence. Neither mechanism appears related to binding kinetics.

Immunological cross-reaction between a naturally occurring galactan, agarose, and an LPS locus for immune lysis of Neisseria meningitidis by human sera.

An immunological cross-reaction between agarose, a naturally occurring galactan, and an antigenic determinant which is a locus for human bactericidal antibody within the LPS of group Y strains of N. meningitidis was investigated. Bactericidal antibody in the convalescent serum of a child from whom a group Y, type IX strain was isolated could be absorbed by highly purified agarose in bead form (Sepharose), but not by a dextran gel (Sephadex). It was inhibited by agarose as a linear polymer and by the strain's LPS, but not by a heterologous LPS from a group B, type II strain of N. meningitidis, nor by the homologous capsular polysaccharide. Both LPS contained galactose; neither was anti-complementary. Agarose antiserum, raised in a rabbit, was bactericidal for the group Y strain, but not for the group B strain. Bactericidal activity in the agarose antiserum could be inhibited by agarose. Immunization with agarose induced haemagglutinating antibody against the group Y strain's LPS which could be absorbed by the group Y, but not the group B strain, and could be reduced by absorption with Sepharose. Absorption with Sepharose also removed the lytic activity against group Y strains of serotypes II and IV from a normal human serum without group Y capsular polysaccharide antibody. We conclude that the cross-reaction resides in the fine structure of the galactose constituent of the group Y strains' LPS.

Elaboration of both the group W135 and group Y capsular polysccharides by a single strain of Neisseria meningitidis.

A single strain (8021) of Neisseria meningitidis, isolated from a child with disseminated meningococcal disease, was found to elaborate two serogroup-specific capsular polysaccharides-Y and W135. The original isolate as well as the progeny of ten single colony sub-isolates each agglutinated with both group Y and group W135 serogrouping antisera. The capsular polysccharide of strain 8021 contained the chemical constituents of both the W135 and Y capsular polysaccharides in a ratio of about 2.5:1. The patient responded immunologically to both capsular polysaccharides with haemagglutinating antibodies. Analysis by double diffusion in agar revealed that the capsular polysaccharide of strain 8021 contained individual molecules of group W135 and group Y capsular polysaccharides as well as a mosaic molecule containing both antigenic determinants.

Vaginal colonization with group B streptococcus: a study in college women.

Vaginal specimens for culture of group B Streptococcus and anonymous questionnaires were obtained from 499 college women. Group B Streptococcus was isolated from 90 (18.0%) of the participants. A selective broth medium was more sensitive for detection of vaginal isolates (85 of 493; 17.2%) than was direct inoculation of blood agar plates (44 of 466; 9.4%). The most prevalent serotypes among the isolates were type III (37.9%) and type II (25.3%). Logit analysis identified four factors associated with a higher prevalence of vaginal colonization with group B Streptococcus. These organisms were isolated significantly more often from (1) women who had an intrauterine device (50% vs. 18.6%; P less than 0.001), (2) sexually experienced women (20% vs. 7.1%; P less than 0.02), (3) women studied during the first half of the menstrual cycle (26.5% vs. 14.5%; P less than 0.01), and (4) women 20 years of age or younger (21.4% vs. 14.8%; P less than 0.05). The prevalence of colonization with group B Streptococcus was not related to sexual practices, history of venereal disease, use of oral contraceptives, presence of gynecologic symptoms, use of antibiotics, race, educational level, marital status, or history of pregnancy.

Antigenic specificity of opsonophagocytic antibodies in rabbit anti-sera to group B streptococci.

An opsonophagocytic assay has been developed which requires human polymorphonuclear leukocytes, immune serum, and complement for optimal killing of Group B streptococci. Only with all three of these components was killing of greater than 1.0 log10 of the initial inoculum achieved, using rabbit antisera directed to homologous strains of each of the five known serotypes of Group B streptococci. Titers of specific antisera which opsonized the strains and resulted in greater than 1 log 10 reduction of colony-forming units, ranged from 1:100 (serotype Ib) to 1:3200 (serotype Ia). Cross-reactions between serotype-specific sera and heterologous strains were seen in certain instances. Type Ic strain and serotype Ic antiserum demonstrated cross-reactions with types Ia and Ib which were explainable by known shared antigens among these types. The only other cross-reaction which resulted in greater than 1 log 10 reduction in colony-forming units was when unabsorbed antiserum to strain Ia was used to opsonize a strain of serotype III. Opsonization of 10 serotype III strains was demonstrated with a single type III antiserum. Killing of nine of these strains required polymorphonuclear leukocytes, complement, and antiserum, but one strain, D136C, the reference strain, could be killed (greater than 1 log 10 reduction in colony-forming units) without either complement or specific antiserum. Inhibition studies were performed utilizing large m.w. polysaccharide antigens extracted from each serotype. These antigens inhibited opsonization of homologous strains by homologous antisera with 50% inhibition points ranging between 0.5 and 4 mug.

Comparison of bacteriological methods for the isolation of group of B Streptococcus from vaginal cultures.

Three bacteriological techniques for the isolation of group B streptococci in vaginal cultures were compared. A selective broth medium (SBM) containing gentamicin and nalidixic acid was more sensitive for the detection of vaginal isolates (28/76, 36.8%) from 76 women enrolled in a venereal disease clinic than was an identical selective plate medium (SPM) (17/76, 25%). Similarly, SBM allowed identification of positive cultures from college women (82/459, 17.9%) significantly more often than direct inoculation of swabs onto nonselective blood agar medium (43/460, 9.4%; chi2 = 42.2, P = less than 0.001). Failure to isolate group B streptococci detected in SBM occurred in 32.1% cultures by SPM and 49.4% of cultures by nonselective agar medium. Multiple serotypes were detected in a single vaginal culture from approximately 5% of the patients studied. These data support the routine use of SBM for the most accurate identification of women vaginally colonized with group B Streptococcus.