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Stable clones of 31 mouse hybridomas that produce monoclonal antibodies (MAbs) against human IgG antigenic determinants were obtained. The number of hybridomas of different specificity described are: 2 anti-IgG1 Fc, 1 anti-IgG2 Fc, 1 anti-IgG2 Fd, 2 anti-IgG3 Fc, 2 anti-IgG3 hinge, 3 anti-IgG4 Fc, 3 anti-IgG4 Fd, 2 anti-nG4m(b), 4 anti-IgGFc, 2 anti-IgGFd, 1 anti-kappa, 1 anti-lambda, 1 anti-non IgG1, 2 anti-non IgG2, 2 anti-non-IgG3, 2 anti-non-IgG4. Evidence is presented validating their specificity. Some MAbs demonstrated to be avid, potent, and specific for well defined IgG-subclass epitopes may be partially or completely inactive in other assay systems, presumably because of different presentations of antigen epitopes. In general, this problem requires careful writing of protocols describing the use of MAbs.

The titers and isotypes of antibodies to specific proteins of the human immodeficiency virus were determined by Western blot analysis of sera from 107 homosexual men.Antibody titers were generally lower in sera from patients with the acquired immudeficiency syndrome (AIDS) and in sera from men whose condition subsequently progressed to AIDS than in sera from men who had not progressed to AIDS. We found no evidence of isotypic prominence or restriction of the antibody response. In multivariate analysis, lower levels of CD4 helper cells were most highly associated with progression to AIDS. Lower antibody titers to the envelope protein gpllO, the core protein p24, and the reverse transeriptase enzyme p51/65 were also predictive of progression to AIDS independent of their Association with CD4 cell levels. These data suggest that differences in antibody levels are not simply a consequence of severe imnmunodeficiency but may be markers for control of infection.

Shiga-like toxin II (SLT-II) was purified to apparent homogeneity from Escherichia coil K-12 strain NM522 containing the cloned toxin genes on recombinant plasmid pEB1. Purification was accomplished by a series of column chromatography techniques: anion-exchange, chromatofocusing, cation-exchange, and monoclonal antibody affinity chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the pure toxin showed that SLT-II consisted of A and B subunits with apparent molecular weights of 32,000 and 10,200 + 800, respectively. A band of molecular weight 25,000 was also observed after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and identified as the Al subunit by Western immunoblot analysis with toxin-specific monoclonal antibodies (MAbs). The pl of the purified toxin was 5.2. Approximately 1 pg of pure SLT-ll was a 50% cytotoxic dose for HeLa cells. The toxin was neutralized by polyclonal antibodies and MAbs to SLT-II, but was not neutralized by polyclonal antibodies or MAbs to SLT-I. Five hybridomas against SLT-II were produced (BC5 BB12, DC1 EH5, EA5 BA3, ED5 DF3, and GB6 BA4). Culture supernatant fluids containing MAbs from these hybridomas did not neutralize the cytotoxicity of SLT-I or Shiga toxin. Western blot analysis showed that two MAbs (MAb DC1 EH5 and MAb GB6 BA4) recognized the A and Al subunits of SLT-I and three MAbs (MAb BC5 BB12, MAb EA5 BA3, and MAb ED5 DF3) recognized the B subunit of SLT-II. MAb BC5 BB12 was used to prepare an affinity column for toxin purification.

Monoclonal antibodies (MAbs) to Naegleria fowleri, the etiologic agent of primary amebic meningoencephalitis (PAM), have been produced and used as probes to identify N. fowleri amebae in brain sections of patients who died of that disease. These MAbs were characterized for their specificity by the indirect immunofluorescence assay (IIF), dot immunobinding assay (DIBA), and enzyme-linked immunotransfer blot technique (EITB). The MAbs reacted intensely with all strains of N. fowleri tested originating from different geographic areas in the IIF and DIBA tests, but showed no reactivity with four other species of Naegleria, N. gruberi, N. jadini, N. lovaniensis, and N. australiensis, or a strain of Acanthamoeba castellanii. In the EITB assay the MAbs reacted with the antigens of N. fowleri and produced intensely staining bands at the 160-, 104-, 93-, and 66-kilodalton (kDa) regions and several minor bands at the 30and 50-kDa regions. The MAbs also reacted with the antigens of N. lovaniensis and produced a darkly staining band at 160 kDa and a diffusely staining band at 116 kDa, indicating that these antigens were shared by the two species. The MAbs, however, showed no reactivity with N. jadini and N. gruberi in the EITB assay.

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Lymphocyte subset enumerations, antibody titers to specific proteins of human immunodeficiency virus (HIV), and measurement of infectious HIV titers in peripheral blood mononuclear cells were performed on serial blood specimens from 15 HIV-infected homosexual men with chronic lymphadenopathy syndrome (LAS); 6 of these men have subsequently progressed to AIDS (progressors), and 9 have remained clinically stable (nonprogressors). For the earliest samples studied, no test distinguished those who would progress to AIDS from those who have not. The two groups diverged significantly about 1 year before AIDS diagnosis in the progressor group. Virus titers rose in progressors but remained relatively stable in nonprogressors. CD4 T cells and the CD4 T cell subset, 4B4, declined more rapidly in progressors than in nonprogressors. HIV antibody titers tended to decline in progressors, but the differences were significant only for antibody and to the pol-encoded proteins, p51/65, and the gag-encoded polyprotein, p55. Before the onset of clinical AIDS, progressors are distinguished from nonprogressors by markedly different rates of CD4 cell depletion and virus replication, but the elements that control these dynamics remain to be defined.

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