A myeloma hybrid producing antibody specific for an allotypic determinant on "IgD-like" molecules of the mouse

Optimization of Selenium Inclusion Level in the Larval Diet of Labeo rohita

The nutritional requirement of fish larvae remains a limiting factor in advanced aquaculture. Micronutrients are crucial for early development, but their dietary inclusion level in the larval feed of carps has not been standardized. The present study was executed to determine the optimum dietary inclusion level of organic and inorganic selenium in the larval feed of Rohu, Labeo rohita. A 35-day feeding trial in triplicate under semi-control conditions was conducted in 21 troughs divided into seven groups. Each trough (capacity 4.0 L) contained 200 larvae (average body weight 0.4 mg). The first group (control) was reared on nano-particulate basal diet (CP 50%), while three groups Se-Na(0.5), Se-Na(1), and Se-Na(1.5) were fed basal diet supplemented with graded levels (0.5-1.5 mg/kg diet) of inorganic form of Se, sodium selenite (Se-Na). The last three groups (Se-Met(0.5), Se-Met(1), and Se-Met(1.5)) were fed organic form of dietary Se, selenium methionine (Se-Met) at the same inclusion level as Se-Na. Results indicated the curvilinear relationship of dietary Se levels with body weight, activity of digestive enzymes (protease, amylase, lipases, and trypsin), and antioxidant enzymes (SOD, CAT, POD, and GSH-Px) activity, intestinal villi, width, and absorptive area. A positive correlation was observed with up to 0.5 and 1 mg/kg diet of Se-Na and Se-Met, respectively; however, above these levels, a negative impact was observed. The upregulation of growth hormone mediator (IGF-1) and downregulation of heat shock protein (HSP-70) also followed a similar trend in response to Se-Na and Se-Met inclusion. Based on the results, 1 mg/kg diet Se-Met could be considered the optimum level and is recommended for the early rearing of rohu larvae.

Extraction of naturally occurring peptides versus the tryptic digestion of proteins from fetal versus adult bovine serum for LC-ESI-MS/MS

The naturally occurring peptides and digested proteins of fetal versus adult bovine serum were compared by LC-ESI-MS/MS after correction against noise from blank injections and random MS/MS spectra as statistical controls. Serum peptides were extracted by differential precipitation with mixtures of acetonitrile and water. Serum proteins were separated by partition chromatography over quaternary amine resin followed by tryptic digestion. The rigorous X!TANDEM goodness of fit algorithm that has a low error rate as demonstrated by low FDR q-values (q ≤ 0.01) showed qualitative and quantitative agreement with the SEQUEST cross correlation algorithm on 12,052 protein gene symbols. Tryptic digestion provided a quantitative identification of the serum proteins where observation frequency reflected known high abundance. In contrast, the naturally occurring peptides reflected the cleavage of common serum proteins such as C4A, C3, FGB, HPX, A2M but also proteins in lower concentration such as F13A1, IK, collagens and protocadherins. Proteins associated with cellular growth and development such as actins (ACT), ribosomal proteins like Ribosomal protein S6 (RPS6), synthetic enzymes and extracellular matrix factors were enriched in fetal calf serum. In contrast to the large literature from cord blood, IgG light chains were absent from fetal serum as observed by LC-ESI-MS/MS and confirmed by ELISA.

Optimization of inclusion level of lipid in larval diet of Labeo rohita (Hamilton, 1822)

Formulation and preparation of larval feed according to the requirement of Indian major carp is a prerequisite for improving the survival (%) and growth during early developmental stages. A feeding trial of 50 days in a replicate of five was conducted to determine the optimal inclusion levels of fish oil (lipid) in the larval diet of Labeo rohita. Four isonitrogenous (50% CP) nanoparticulate diets with four lipid inclusion levels, L5 (5%), L7 (7%), L9 (9%), and L11 (11%) were prepared and fed to four groups of rohu (Labeo rohita) larvae. At the end of feeding trial, survival (%), growth performance, digestive enzyme activity, gut morphology, and expression of growth and feed intake genes were evaluated. All pairwise comparisons among groups indicated higher growth performance (weight gain, specific growth rate, and daily weight gain), survival (%), and IGF-1 gene expression of the L9 group followed by the L7 while the L11 showed poor performance even less than L5. All studied intestinal enzymes except amylase showed a similar trend. Amylase showed comparable results among L7, L9, and L5, while L11 showed the lowest value. The intestinal villi length also showed higher values in L9 followed by L7, and lowest in the L11 group. Feed intake regulating genes, leptin showed lipid inclusion level upregulation, while ghrelin showed the highest expression in the L9 group. Based on growth performance, gut morphology, intestinal enzyme activity, and gene expression analysis, 9% dietary lipid could be recommended to ensure the optimum growth and survival of L. rohita larvae.

Linear and Gaussian Analysis of a Single Enzyme Molecule by LC-MS

The alkaline phosphatase-streptavidin enzyme amplification conjugate (APSA) was diluted and quantified to the equivalent of one enzyme molecule injected on column by monitoring the production of excess adenosine from adenosine monophosphate (AMP) using sensitive and selective enzyme-linked mass spectrometric assay. The APSA enzyme conjugate has a mass of about 195 kDa and catalyzed the production of millions of enzyme products over the course of incubation that may be sensitively quantified by liquid chromatography, electrospray ionization, and mass spectrometry. APSA enzyme conjugate from fg/mL to ag/mL alongside 0 g/mL (control) was incubated with the substrate 1 mM AMP for 2 h in free solution before collecting a 1 μL of sample of the enzyme product adenosine for injection and analysis by LC-MS. The enzyme product adenosine showed a Gaussian distribution after log₁₀ transformation. The safe limit of detection and quantification was approximately 250 zg of APSA enzyme conjugate injected on column. A linear signal with acceptable error was observed at the mass of the enzyme product adenosine from 10 to 10000 zg of APSA enzyme conjugate injected, compared to controls without enzyme. It was possible to make a linear and Gaussian measurement to the single molecule range of the universal APSA enzyme amplification conjugate per micro liter injected with approximately 10% error. This study describes the first linear and Gaussian quantification of enzyme product from the equivalent of one enzyme conjugate molecule injected onto LC-MS for analysis.

Four different clones of mouse anti-acetyllysine monoclonal antibodies having different recognition properties share a common immunoglobulin framework structure

By employing two different immunogens and two different antibody-screening strategies, we established four mouse hybridoma clones producing monoclonal antibodies against N epsilon -acetyllysine. Three different protocols were used in this study; i.e., mice were (1) immunized with an N epsilon -acetyllysine-containing peptide, Gly-Lys(Ac)- epsilon -aminocaproic acid (Aca)-Cys, conjugated to KLH, and the hybridoma clones were screened for their reactivity to a histone H3 peptide containing five acetyllysines; (2) immunized as in "1" and screened with chemically acetylated bovine serum albumin (BSA); (3) immunized with chemically acetylated keyhole limpet hemocyanin (KLH) and screened with chemically acetylated BSA. Antibodies produced by the four different hybridomas established here all reacted with acetyllysine residues, but their reactivity was not the same when evaluated with enzyme-linked immunosorbent assay (ELISA), Western blotting, and resonant mirror sensor analyses. Among the three protocols examined, protocol "3" was especially useful to obtain hybridomas producing anti-N epsilon -acetyllysine antibodies that could detect not only the acetylated histones but also other acetylated proteins. By cloning and sequencing the cDNAs encoding the variable regions of the antibodies, we found that their framework sequences were almost the same, which suggests that some framework amino acids in addition to their complementarity determining regions (CDRs) directly contribute to their recognition function.

Non-overlapping Fas- and BCL-2-regulated death pathways in IgG2a(b)-producing B cells

Using perforin (Pfp)- and/or Fas-dependent cytotoxic pathways, T splenocytes from Igh(a/a) mice are able in vivo to totally and chronically eliminate congenic Igh(b/b) B cells committed to IgG2a(b) production. This phenomenon leads to a characteristic absence of serum IgG2a(b) expression (IgG2a(b) allotype suppression) in, for instance, histocompatible Igh(a/b) or Igh(b/b) mice, having neonatally received such T cells. Because the study of the protective role of BCL-2 oncoprotein against Fas-mediated cell death has generated contradictory findings, we examined the possible impact of constitutive overexpression of transgenic human BCL-2 protein in Igh(b/b) B cells when the latter were exposed in vivo exclusively with the Fas-dependent, anti-IgG2a(b) T cell activity of Igh(a/a) Pfp(0/0) mice. We observed that, despite high intracellular expression of functional transgenic BCL-2 and no up-regulation of the principal BCL-2 inhibitors in whole Igh(b/b) B cells, total, chronic and specific IgG2a(b) suppression was exerted by Igh(a/a) Pfp(0/0) cytotoxic T cells. These data show that, in this model of negative regulation of Ig production, Fas- and BCL-2-regulated mechanisms belong to non-overlapping death pathways at the level of IgG2a(b)-producing B cells, targets of Igh(a/a) T cell-mediated cytotoxicity. Thus, in these mature B cells, the Fas signaling-directly operating via caspase 8-does not involve a mitochondria-dependent pathway regulated by BCL-2.

Evidence of Alternative or Concomitant Use of Perforin- and Fas-Dependent Pathways in a T Cell-Mediated Negative Regulation of Ig Production

To study the possible involvement of perforin (Pfp)- and/or Fas-dependent cytotoxicity pathways in a T cell-mediated negative regulation of Ig production, we used the T cell-induced Ig-allotype suppression model. T splenocytes from Igha/a mice, when neonatally transferred into histocompatible Igha/b F1 or Ighb/b congenic hosts, are intrinsically able to totally, specifically, and chronically suppress the production of IgG2a of the Ighb haplotype (IgG2ab). It has not been established whether the suppression effectors, which are anti-IgG2ab MHC class I-restricted CD8+ T cells, cytolyse IgG2ab+ B targets or whether they only silence Ig production. In this study, using T cells from Igha/a Pfp+/+ or Pfpo/o mice, the latter obtained by crossbreeding, and B cells from Ighb/b Fas+/+ or Faslpr/lpr (lymphoproliferation) mice in appropriate adoptive transfer models, we demonstrated that: 1) under blockage of the Pfp-mediated pathway, Igha/a T cells were still able to induce suppression against wild-type IgG2ab+ B cells, 2) IgG2ab+ B cells with impaired Fas expression were also subjected to suppression by WT Igha/a T splenocytes, and 3) the suppression establishment was totally inhibited when both Pfp- and Fas-dependent mechanisms were simultaneously blocked, i.e., when Igha/a Pfpo/o T cells were used to induce suppression against Ighb/b Faslpr/lpr B cells. These results provide the first demonstration of the existence of alternative or simultaneous use of the major cytotoxic mechanisms in a T cell-mediated down-regulation of an Ig production.

The T/B cell interaction involved in induction of the mouse IgG2ab suppression is restricted by major histocompatibility complex class I, but not class II molecules

To determine the major histocompatibility complex (MHC) restriction of the T/ B cell interaction involved in a negative regulation of Ig production, we used mouse model of T cell-induced IgG2ab suppression in vivo. Normal or specifically triggered T splenocytes from mice of the Igha haplotype, when neonatally transferred into histocompatible Igha/b heterozygotes, are able to induce a specific and total suppression of the IgG2ab allotype. Nevertheless, only transfer of IgG2ab-primed Igha T splenocytes induces this suppression in Ighb/b homozygous congenic mice in which the whole IgG2a isotype production is inhibited. This suppression is chronically maintained by CD8+ T cells, but can be experimentally reversed. We have established that the suppression induction required a CD4+CD8+ T cell cooperation and operated via the recognition by the involved TCR of C gamma 2ab-derived peptides presented by the target B cells in an MHC haplotype-restricted manner. Here, by using Ighb mice genetically deficient for MHC class I (beta 2-microglobulin%, or beta 2m%) or class II (I-A beta%) molecules, we demonstrate functionally that the suppression induction implicates an MHC class I-, but not class II-restricted interaction. Indeed, the anti-IgG2ab T cells transferred into Ighb H-2b I-A beta% mice carry out the suppression process normally, while in Ighb H-2b beta 2m% recipients, their suppression induction capacity is significantly inhibited. Moreover, the C gamma 2ab 103-118 peptide, identified as the sole C gamma 2ab-derived peptide able to amplify the anti-IgG2ab T cell reactivity in Igha H-2b mice, is also able to stabilize the H-2Db, but not the H-2Kb class I molecules at the surface of RMA-S (TAP2-, H-2b) cells. These results indicate that, despite the CD4+/CD8+ T cell cooperation during the induction phase of suppression only MHC class I molecule expression is required at the surface of IgG2ab+ B cells for suppression establishment.

A microELISA assay for detection of anti-HLA activity of mouse monoclonal antibodies using an Astroscan 2100 automated plate reader

A microenzyme-linked immunosorbent assay (microELISA) method has been developed using an Astroscan 2100 system automated plate reader which was initially designed for tissue typing by a two colour fluorescent microcytotoxicity assay. A 96-well plate ELISA used for screening mouse monoclonal antibodies raised against surface HLA antigens has been modified for use with the Astroscan plate reader and 72-well typing trays. The existing substrate 4-methylumbelliferyl-beta-D-galactoside (4MUG) has been replaced with fluorescein-di-beta-D-galactopyranoside (FDG), to provide a wavelength (530 nm) detectable by the Astroscan or other automated plate readers designed for reading microcytotoxicity assay plates. The assay volumes have also been reduced tenfold for use with Terasaki microtest plates. The assay now has the major advantage of requiring only 5 microliters of test supernatant allowing hybridomas to be screened earlier during a fusion and on a wider cell panel. The use of the large panel which includes B lymphoblastoid cell lines (B-LCL) and mouse L cell transfectants expressing HLA genes, reduces the length of time the hybridomas need to be kept in tissue culture before selection. Other advantages include the reduction in the number of target cells required, smaller volumes of reagents throughout the assay and the ability to screen cytotoxic as well as non-cytotoxic monoclonal antibodies. The sensitivity of this microELISA proved to be comparable with the original assay and so provides an efficient screening method for monoclonal antibodies.

Enhancement in Igha mouse strains of the "natural" suppressive activity of normal T splenocytes against the expression of Igh-1b allotype. I. Molecular aspects of the chronic suppression obtained

Several approaches have been used in our attempts to increase the "natural" ability of normal T splenocytes (Tn) from BALB/c or BC8 mice (both Igha) to induce, in F1 hybrids, a suppression of Igh-1b expression (IgG2a of b haplotype). These heterozygous F1 were produced by mating these Igha mice and their Ighb-congenic partners (CB20 and C57BL/6, respectively). The most powerful approaches were to sensitize the Igha mice by either autologous splenocytes coated with Igh-1b or B splenocytes from Ighb-congenic mice. In F1 having paternally inherited the b haplotype the sensitized T splenocytes (Ts) prepared from such mice are able to induce, like Tn, when injected at birth, a chronic suppression of Igh-1b expression. However, the suppression was established with a much higher efficiency: already at 6 weeks of age in 100% of the F1 treated with 1 x 10(7) Ts, vs. a final rate of 70% progressively reached only at 42 weeks of age in the F1 treated with 4 x 10(7) Tn. In F1 having maternally inherited Ighb the differences were even more pronounced than with 4 x 10(7) Tn, i.e. the suppression induction was almost totally ineffective, whereas with 2 x 10(7)-4 x 10(7) Ts, a rate of 100% treated F1 subjected to suppression was reached at 19 weeks of age. As the productions of IgM, IgD and IgA of the b haplotype were not affected by the suppression, the Ts are believed to act on the Igh-1b+ cells. Attempts were also made to induce allotypic suppression of other b allotypes by the use, as sensitizing cells, of myeloma cells carrying Igh-6b (IgM of b haplotype). We failed in revealing any sign of a T cell reactivity against Igh-6b similar to the reactivity against Igh-1b. The use of Igh-6b+ myeloma cells grown in an Ighb or in an Igha background allowed us to assume that the cells responsible for the sensitization are, in the Ighb B lymphocyte population, either the Igh-1b+ lymphocytes or the lymphocytes having passively adsorbed this allotype, or both.

The origin of pigment cells in embryos of the sea urchin Strongylocentrotus purpuratus

A monoclonal antibody (SP1/20.3.1) that recognizes a cell surface epitope expressed by pigment cells in the pluteus larva of Strongylocentrotus purpuratus has been produced. Using indirect immunofluorescence, the epitope is first detected in nonpigmented cells of the vegetal plate after primary mesenchyme ingression. Between the beginning of gastrulation, and when the archenteron is one-third the distance across the blastocoel, SP1/20.3.1-positive cells are free within the blastocoel, at the tip of the archenteron, and dispersed within the blastoderm. Cells at the tip of the archenteron, and mesenchyme near the tip in later stages of gastrulation (secondary mesenchyme), do not express the SP1/20.3.1 antigen. By the completion of gastrulation all SP1/20.3.1-positive cells are dispersed throughout the epidermis. It has been concluded that in S. purpuratus pigment cell precursors are released from the vegetal plate during the initial phase of gastrulation. The cells migrate first to the vegetal ectoderm, and subsequently disperse throughout the ectoderm and develop pigment granules.

Structural heterogeneity of murine IgD during ontogeny

We have studied the expression of the two membrane delta heavy chains (delta 1 and delta 2) and the two native IgD structures (IgDI and IgDII) in neonatal mice. Both delta-chains appear simultaneously during development and neonatal mice, like adults, express equal amounts of delta 1 and delta 2. IgDI and IgDII also appear simultaneously during ontogeny and in the same ratio as expressed by adult mice of the same strain. Thus, when IgD first appears during ontogeny it shows the same structural heterogeneity as observed in adult mice.

Epitope ratio analysis (ERA): a simple radioimmunological method using monoclonal antibodies for the simultaneous analysis of several antigens

Monoclonal antibodies specific for human cell surface antigens were used to develop a technique for the simultaneous analysis of several antigenic determinants. The procedure was used to measure the relative expression of specific cell antigens during cultural growth. Epitope ratio analysis (ERA) is applicable to many systems requiring measurement of such differential antigen expression.

Coated vesicles from human placenta carry ferritin, transferrin, and immunoglobulin G

Coated vesicles prepared by using isotonic gradients retain their contents. Ferritin, transferrin, and immunoglobulin G have been detected in human placental coated vesicles. Triton X-100 extraction of crude coated vesicles removes contaminating uncoated membranes, leaving coated particles and their associated proteins apparently intact; this provides an efficient means of preparing large quantities of coated vesicle proteins. The clathrin cages surround "cores" of structural protein containing polypeptides of 100,000 and 50,000 molecular weight.

Hybridomas: a new dimension in biological analyses

Since the first report of hybridomas producing monoclonal antibodies by Kohler and Milstein in 1975, this technique has spread to nearly all areas of biological, biochemical, and biomedical research. Watching the use of these methods spread from immunologists to cell biologists, developmental biologists, biochemists and to other biological disciplines and observing the nearly logarithmic increase in publications using these reagents has been in itself fascinating and informative. An overview of the development of this technology and its applications is presented including the use of monoclonal antibodies to study cell surface molecules, differentiation antigens, receptors, and histocompatibility antigens. The use of these antibodies to analyze microorganisms and parasitic antigens as well as their use in the genetic analysis of human cell surface antigens and the detection of polymorphic variation in enzymes and other proteins is discussed. Examples of the application of monoclonal reagents to the study of tumor cell biology including the labeling of metastatic tumor cells and the detection of cell surface molecules implicated in the regulation of growth control and cell division are provided.

Physiology of IgD. I. Compensatory phenomena in B lymphocyte activation in mice treated with anti-IgD antibodies

The role of delta-positive cells in the immune response was studied by comparing the effects of treatment with allotype-specific IgD hybridoma antibody on homozygous BALB/c or SJL/J and heterozygous (BALB x SJL)F1 mice. Homozygous mice, injected from birth with the relevant anti-delta antibody, made primary or secondary immune responses to intravenously injected trinitrophenyl (TNP)-Brucella abortus, TNP-Ficoll, and TNP-keyhole limpet hemocyanin, which did not differ significantly from those of control mice, despite the fact that IgD+ cells were depleted and Ig+ cells were markedly reduced in the spleens of treated mice. Responses in nodes draining a local injection of TNP-Brucella abortus were, however, significantly suppressed. Heterozygous mice, injected from birth with either anti-Ig-5a or anti-Ig-5b, showed a marked reduction in the number cells producing IgG antibody of linked allotype specificity in the secondary response to intravenously injected sheep erythrocytes. A corresponding decrease in the amount of serum IgG2a of that allotype specificity was also noted. However, in agreement with the results obtained in homozygotes, heterozygotes injected simultaneously with anti-IgD directed against each of the allotypes made normal, if not enhanced, plaque-forming cell responses of both allotype specificities. Similarly, serum IgG2a levels were normal in all but one mouse treated in this fashion. These results indicate that IgD+ cells are not essential for an immune response in vivo. Although the delta-positive cell is used preferentially under normal conditions, it appears that an alternative mechanism exists by which, in the absence of these cells, the animal is able to make a normal immune response.

Biogenesis of membrane-bound and secreted immunoglobulins: two primary translation products of the human delta chain, differentially N-glycosylated to four discrete forms in vivo and in vitro

Structural differences between the heavy chain of membrane IgD (delta m) and the heavy chain of secreted IgD (delta s) were investigated by using a human lymphoblastoid cell line that expresses idiotypically identical IgM and IgD. In a wheat germ cell-free system, mRNA from this cell line was shown to encode two distinct delta chains that differed in molecular weight. When translated in vitro in the presence of dog pancreatic microsomal membranes or when synthesized in vivo, these two delta chains were processed to four discrete glycosylated forms, all of which shared idiotypic determinants, C region determinants, and light chain linkage. As shown by digestion with endo-beta-N-acetylglucosaminidase H, these four delta forms represent two delta polypeptide chains that are differentially N-glycosylated. Pulse-chase experiments demonstrated that, after endo-beta-N-acetylglucosaminidase H treatment, delta m has a higher molecular weight than delta s. After integration into dog pancreatic microsomal membranes in vitro, delta m was found not to have a large cytoplasmic domain exposed to proteolytic digestion. The finding that delta m and delta s differ in primary structure is analogous to previous work with the corresponding heavy chains of IgM (mu m and mu s) from the same cell line. Thus, this cell line produces four Ig heavy chains (mu m, mu s, delta m, and delta s), with the same idiotype. The observation of differential N-glycosylation, apparently unique for the delta class, is discussed.

Monoclonal antibodies derived from hybrid myelomas

The hybrid myeloma technique for the production of monoclonal antibodies has been widely applied in many areas of biological and medical research. The strategy for derivation of monoclonal antibodies requires careful consideration of factors such as the initial immunization with antigen, choice of myeloma cell line, and method of assay for the desired antibodies. Once the hybrid lines have been isolated and established in culture they will continue to secrete the monoclonal antibody indefinitely, providing routine cloning is carried out to eliminate the accumulation of variants. Production of human monoclonal antibodies is at present limited by the lack of suitable parental myeloma cell lines although some success has been reported using both mouse and human cell lines. Under many assay conditions monoclonal antibodies behave differently to antisera directed against the same antigen but some of these differences are eliminated when two or more monoclonal antibodies are mixed. The unique properties of monoclonal antibodies also may allow subtle distinctions to be made between closely related antigens.

Sequential expression of B lymphocyte surface antigens in vitro

Serological techniques were used to examine the process of sequential surface antigen expression on differentiating B cells in vitro. A 4-day culture system is described in which bone marrow lymphocytes from neonatal mice acquire in sequence the ability to express Lyb-2, IgM, Ia and IgD in response to a 3-h induction with E. coli lipopoly-saccharide (LPS). Lyb-2 can be induced on day 1, IgM can be induced after 24 h, Ia after 48 h and IgD only after 96 h in culture. This sequence mimics the order of appearance of B cell surface antigens during ontogeny. When DNA synthesis is blocked from 0.24 h with hydroxyurea (HU), all surface antigens can be induced simultaneously by LPS. Immunoselection of one antigen-bearing population results in the loss of cells bearing other B cell antigens indicating that the surface antigens are induced on the same cells. When both HU and LPS were added to the cultures from the start, IgM appears after 11-14 h, Ia afer 14-15 h and IgD only after 19 h. Induction of antigen was demonstrated by he cytotoxicity assay, quantitative absorption and the protein A sheep red blood cell rosetting assaying. The results obtained show that there is a population of surface IgM-negative precursor B cells in young bone marrow which, when grown in vitro, become sequentially inducible for expression of B surface antigens. Inhibition of DNA synthesis promotes acquisition of the inducible state, and the sequence of antigen expression is correlated with specific time intervals after DNA synthesis has stopped.

Monoclonal rat antibodies to murine IgM determinants

A series of 6 hybrid clones are described which produced antibodies directed to murine IgM. These were derived by immunizing rats with W279 B-lymphoma cells and then fusing the immune spleen cells to enzyme-deficient murine plasmacytoma cell lines. Immunoenzymatic techniques were used to select clones producing desirable antibodies to cell surface or soluble antigens. Antibodies from 3 of the clones (293.14, 414.18 and 307.5) preferentially bound to idiotypic determinants of W279 immunoglobulin whereas the remaining 3 clones made antibodies which bound to various myeloma and normal cell surface IgM molecules. One IgM-specific clone (287.2) produced antibody of relatively low avidity. The two other clones (81.20 and 331.12) which secreted anti-mu antibodies appeared to be directed to determinants which differed in glutaraldehyde lability and expression in F(ab')2 preparations.

Switch from hapten-specific immunoglobulin M to immunoglobulin D secretion in a hybrid mouse cell line

From a hybrid mouse cell line (B1-8) that secreted an IgM, lambda 1 anti-(4-hydroxy-3-nitrophenyl)acetyl antibody but that had no detectable surface IgM, selection for a variant with lambda 1 chains on the surface resulted in the isolation of a line that had switched from mu to delta expression. The surface and secreted Igs of this line were typed as IgD with two monoclonal antibodies, and the parental IgM and variant IgD molecules carried the same variable regions as judged by hapten-binding and idiotypic analysis. The surface and secreted delta chains of the IgD variant have apparent molecular weights of 64,000 and 61,000, respectively. However, the unglycosylated secreted delta polypeptide chain has a molecular weight of only 44,000. The secreted IgD exists predominantly in the delta 2 lambda A2 form, does not contain J protein, is relatively stable in serum, and does not fix complement.

Use of an enzyme-linked immunosorbent assay (ELISA) for screening of hybridoma antibodies against cell surface antigens

A micro-ELISA for screening of antibodies from hybridoma cultures against surface antigens of human melanoma is described. The technique employs alkaline phosphatase-conjugated protein A and target cells attached to poly-L-lysine-coated microtiter plates. The micro-ELISA is equally sensitive as the radioimmunoassay. Mild glutaraldehyde treatment of cells did not lead to an appreciable loss of antigen activity. The fixed cells can be stored at 4 degrees C for at least 6 weeks. It is concluded that the ELISA is superior to the radioimmunoassay in the following aspects: (1) exclusion of radioactive hazards, (2) speed of performance, and (3) lower costs.

The bovine lymphoid system: II. Derivation and partial characterization of monoclonal antibodies against bovine peripheral blood lymphocytes

We have raised monoclonal antibodies to produce reagents specific for bovine lymphocyte subpopulations. Spleen cells from mice immunized with bovine peripheral blood lymphocytes were fused with X63-Ag8 myeloma cells and eleven myeloma-hybrids which secreted antibody specific for bovine lymphocytes were doubly cloned. Five of the hybrids secreted antibodies which bound to the majority of bovine lymphocytes. Two of these antibodies were specific for polymorphic antigens. One antibody bound to B lymphocytes and serum IgM molecules. The remaining five bound to subpopulations of lymphocytes. Four monoclonal antibodies bound only to bovine cells while six also bound to lymphocytes from other bovidae. None bound to human lymphocytes. We discuss the difficulty of correlating the specificities of monoclonal antibodies to functional lymphocyte subpopulations in outbred animals where few other defined markers are available.

Augmentation of in vitro humoral immune responses in the mouse by an antibody to IgD

Heterologous anti-delta-chain antibodies have an adjuvant effect on specific in vivo humoral immune responses to simultaneously, or subsequently, injected antigens in the rat and rhesus monkey. We have used a hybridoma-secreted antibody that binds murine delta-chain of the allotype (4.22aM delta a) to study this phenomenon in the mouse and to investigate the mechanism of this effect. Injection of 4.22aM delta a into BALB/c mice removes almost all surface IgD (sIgD) from splenic B lymphocites. sIgD does not reappear until the serum level of 4.22aM delta a decreased 5-7 d after injection. 4.22aM delta a fails to induce detectable proliferation or to raise total serum Ig levels substantially above control values. However, 4.22aM dalta a injected 24 h before antigen elicits an approximately twofold enhancement of serum IgM and a 3- to 10-fold enhancement of serum IgG anti-trintriphenyl (TNP) antibodies in response to immunization with optimal doses of TNP-Ficoll or TNP-sheep red blood cells (TNP-SRBC). 4.22aM delta a injected 1 wk before or 3 d after TNP-SRBC, however, has no effect on IgG anti-TNP levels. The adjuvant effect of anti-delta-chain antibody was markedly decreased when suboptimal antigen doses were used. Furthermore, even in the case of TNP-Ficoll, a relatively T-independent antigen, the ability of 4.22aM dalta a to enhance the anti-TNP antibody response was T cell dependent. Our data suggest that the binding of anti-delta-chain antibody to cell sIgD may partially activate B lymphocytes and make them more capable of differentiating into antibody-secreting cells when stimulated by antigen-specific T cell help.

Genetic control of murine IgD structural heterogeneity

Murine B lymphocytes express two native forms of surface IgD: IgDI consists of two delta heavy chains and two light chains; IgDII consists of one heavy chain and one light chain. The relative amounts of IgDI and IgDII present on spleen cells were found to vary significantly among different strains of mice. Genetic evidence demonstrated that the IgDI/IgDII ratio is linked to the Igh-5 allotype. (The delta heavy chain is the product of the Igh-5 locus). Mice bearing the Igh-5e allotype have a low ratio, and mice bearing the Igh-5a or Igh-5b allotype have a high ratio. The Igh-5 locus and the gene controlling the IgDI/IgDII ratio appear to map to the region between the Igh-6 and Igh-V loci.

Methods for derivation and detection of anti-parasite monoclonal antibodies

We describe detailed methods for derivation and cloning of myeloma hybrids which secrete antibodies specific for antigens of protozoan parasites. The methods were designed to enable the derivation of large numbers of specific monoclonal antibodies and to give high cloning efficiencies of desired hybrids. Although special attention is paid to derivation and detection of anti-parasite antibodies, the methods can be applied to many different antibody-antigen systems. Using the described methods we have isolated more than 90 myeloma hybrids which secrete antibodies specific for antigens of African trypanosomes and Theileria parasites, thus illustrating their effectiveness.

H 9/25 monoclonal antibody recognizes a new allospecificity of mouse lymphocyte subpopulations: strain and tissue distribution

C3 H/He-mg mice were immunized with C57BL/10 (B10) spleen cells and the immune spleen cells were fused with BALB/c myeloma cells (NS1). One of the monoclonal antibodies (H9/25 antibody) produced by the hybrid cells was studied. It reacts with subpopulations of B10 lymphocytes as well as some lymphoid tumor lines including some of the Abelson virus-induced leukemias. The antigen recognized by H9/25 antibody is expressed on lymphocytes from all the B10 congeneic mice tested as well as some other strains of mice. No linkage between genes coding for the antigen and H-2 loci was found as judged by its presence on cells of the B10 strains regardless of H-2 type and the distribution of the antigen on Bailey recombinant inbred mice. The antigen is expressed on subpopulations of lymph node cells, spleen cells, thymocytes and bone marrow cells. The strain distribution of the H9/25 antigen seems to be identical to that of Ly-6, Ly-8 and Ala-1 antigens. However, the tissue distribution of the antigen recognized by H9/25 antibody, while similar to these alloantigens, is unique and the antigen may be distinct from the other alloantigens.