Phylogeny of immunoglobulins

Bacterial Diversity in a Sri Lankan Geothermal Spring Assessed by Culture-Dependent and Culture-Independent Approaches

Hot springs harbour diverse and interesting groups of microorganisms adapted to extreme conditions. However, due to limitations in the culture-dependent approach, most of such thermophiles remain uncultured and unexplored. Hence, this study was conducted to gain a comprehensive understanding of the bacterial diversity of Mahapelessa hot spring, Sri Lanka using both culture-dependent and culture-independent approaches. The in situ temperature of the water sample was 44.5 °C and the pH was 8.14. 16S rRNA Sanger sequencing of DNA extracted from the 18 bacterial isolates revealed the presence of eight genera belonging to two phyla: Proteobacteria (84%) and Firmicutes (16%) and the most abundant genus being Klebsiella. A total of 23 bacterial phyla representing 80 classes, 43 orders, 123 families, 205 genera and 83 species were detected by 16S rRNA V3-V4 region by amplicon metagenome sequencing of DNA extracted from water samples, where the most abundant phylum was the Proteobacteria (57.39%), followed by Firmicutes (23.7%) and Chloroflexi (4.14%). The three phyla Actinobacteria, Planctomycetes and Bacteroidetes were also detected less than 3% in abundance while 4.48% of bacteria could not be fit into any known phylum. The most abundant genera were Burkholderia (14.87%), Desulfotomaculum (7.23%) and Stenotrophomonas (6.1%). Four strictly anaerobic bacteria, Anaerosolibacter carboniphilus (0.71%), Bellilinea caldifistulae (0.04%), Salimesophilobacter vulgaris (0.1%), Anaerobacterium chartisolvens (0.12%); two potential plant growth-promoting bacteria, Azospirillum halopraeferens (0.04%) and Bradyrhizobium liaoningense (0.16%) and one potential alkali tolerant and sulphate-reducing bacterium, Desulfovibrio alkalitolerans (0.45%) were recorded. Pigmentiphaga sp. was isolated from Mahapelessa hot spring and to the best of our knowledge, this is the first record of this genus from a hot spring. This study gives insight into the vast bacterial diversity present in the Mahapelessa hot spring from the culture-independent approach which could not be identified using standard culturing techniques.

Identification of five different IGHV gene families in owl monkeys (Aotus nancymaae)

In order to characterize immunoglobulin heavy-chain variable (IGHV) genes in Aotus nancymaae monkeys, different mRNAs encoded by five IGHV families in this non-human primate were molecularly analysed considering their paramount importance in antibody production in an immune response. This study reports gene products exhibiting 91% amino acid similarity with IGHV1, IGHV2, IGHV3, IGHV4 and IGHV7 human IGHV families. Our analyses suggest that the IGHV gene has several conserved characteristics in humans and A. nancymaae. Several amino acid residues that are highly conserved in all family members described in humans were also present in these families in A. nancymaae. Antibody diversity in these families has remained the same since divergence of both species. Our study continues to provide evidence supporting the use of A. nancymaae monkey as an animal model for studying antibody response.

Development of the concept of immunologic specificity: IV

We have attempted, in this series of essays on the development of the concept of immunologic specificity, to trace the history of one of the most central ideas in immunology (and indeed in biology in general). The result must be viewed as preliminary and incomplete and as an invitation to others to add, to amend, and even to disprove. Nevertheless, several interesting conclusions may be drawn, which reveal much about the workings of immunology in particular, and perhaps science in general. First, the roots of any important scientific concept (such as that of immunologic specificity) do not grow in isolation; they draw nourishment from many other disciplines. Similarly, the growth of an important concept within a given discipline will have far-reaching implications and fruits for other fields of science. Second, we may note a marked change in the manner in which immunology is currently practiced, compared with that of the end of the last century. The quantum leaps forward in funding, in numbers of scientists, and in masses of crucial data have not been without a certain cost--the substantial reduction in elegant personal style that characterized so many of our scientific forebears, and that makes so pleasant the reading of their reports. Finally, we see again and again how much his philosophical bases and disciplinary upbringing determine a scientist's approach, the questions that he asks, and the type of answers he will accept. Throughout much of immunology's history, as Jerne put it so well (44), cis- and trans-immunologists hardly spoke to one another. Or rather, a cis-immunologist sometimes spoke to a trans-immunologist, but the latter rarely answered! Fortunately, one of the attributes of scientific progress is a merging of these disparate languages, and eventual mutual comprehension.

Immunoregulatory circuits that modulate responsiveness to suppressor cell signal. Failure of B10 mice to respond to suppressor factors can be overcome by quenching the contrasuppressor circuit

The in vitro antibody response of spleen cells from B10 strain mice is not suppressed by factor preparations made by primed Ly-2 T cells, although these preparations can suppress the in vitro antibody response of spleen cells from other mouse strains (1-3)2. The factor preparations from Ly-2 cells contain at least two separable activities: one that acts as a suppressor moiety (Ly-2 T cell suppressor factor [Ly-2 TsF]) and a second factor that acts as an inducer of contrasuppression (Ly-2 TcsiF); the latter initiates a series of cellular interactions that leads to the inhibition of suppression that we refer to as contrasuppression. Removal of components (either cellular or humoral) of the contrasuppressor circuit makes spleen cells from B10 strain mice as easily suppressible as are those of other mouse strains. Thus, removal of the contrasuppressor inducer cell and/or its biologically active product with the use of an anit-J serum, or removal of the functional acceptor of the inducer cell with the same or other (Ly-2; Qa-1) antisera breaks the B10 suppressor barrier. Contrasuppressive activity. but not helper activity can be eluted from anit-I-J immunoabsorbents. The addition of B10 T cells to either B6 or B10 spleen cell culture deprived of acceptor cells for the TcsiF reconstitutes contrasuppression more efficiently than does the addition of C57BL/6 T cells. Ly-2 TcsiF is more cross-reactive than is Ly-2 TsF so that absorption of factor preparations from sheep erythrocyte-primed Ly-2 cells with horse erythrocytes also breaks the B10 suppressor barrier. The hyperresponsiveness of splenic T cells from B10 strains to Ly-2 TcsiF may be an in vitro exaggeration of a normal in vivo process. Thus it is possible that one can take advantage of this unusual situation to help dissect out the cellular and subcellular components of T cell circuits that moldulate sensitivity to immunoregulatory signals.

Identification of human glandular kallikrein in the beta cell of the pancreas

To determine the cellular localization of glandular kallikrein in the human pancreas, immunohistochemical studies were performed with a monospecific antibody against the antigenically identical urinary kallikrein (urokallikrein). The localization of glandular pancreatic kallikrein to the beta cells of the islets was the same as that of insulin in normal human pancreas and in two islet-cell tumors. When beta cells were lacking in islet-cell tumors or in the pancreas of a patient with juvenile-onset diabetes, kallikrein antigen was not detectable. Anti-urokallikrein absorbed with purified urinary or pancreatic kallikrein no longer identified a pancreatic antigen, whereas absorption with insulin had no effect. The beta-cell localization of human pancreatic kallikrein, an endopeptidase that, in concert with carboxypeptidase B, converts bovine proinsulin to a polypeptide with the electrophoretic mobility of insulin, suggests that pancreatic kallikrein may be involved in the physiologic activation of proinsulin.

Genetic determination of antibody specificity. Gene translocation and fusion, the molecular basis for the differentiation of the antibody-producing cell

The best system for the study of cell differentiation is a cell which in its differentiated state differs only by one product. This is the case in the immune system. The undifferentiated, but omnipotent stem cell differentiates into a committed B cell which produces only one type of specific antibody out of a million different, genetically fixed possibilities. Gene translocation and fusion is the basis of this differentiation process.

Immunoglobulin evolution: chemical study of clawed toad (Xenopus laevis) heavy and light chains

NH2 terminal amino acid sequence determinations of clawed toad (Xenopus laevis) immunoglobulins indicate that approximately 30% of the heavy chains and less than 5% of the light chains have unblocked NH2 termini. The major amino acid sequence of the X. laevis 7S immunoglobulin heavy chains is the same as that of the 19S immunoglobulin heavy chains. Thus in the synthesis of the heavy chains, the VH genes coding for unblocked heavy chains can associate with CH genes of both the 19S and 7S classes. This association is particularly important in amphibians because, in contrast to mammals and birds, the majority of amphibian antibody-producing cells synthesize both 19S and 7S immunoglobulins and do not participate in the 'genetic switch' characteristic of lymphocyte differentiation in higher organisms. In X. laevis, the major amino acid sequence at the first twenty-four positions of the unblocked heavy chains shows approximately 54% difference from the prototype amino acid sequence of the mammalian VHIII subgroup. Thus, the VHIII gene(s) must have started to appear after the evolutionary divergence of the common ancestor of mammals and birds from the amphibian line. The amino acid composition of the X. Laevis 7S immunoglobulin heavy chains differs from that of its 19S immunoglobulins as well as those of human IgG and IgA. These data support the concepts (a) that amphibian 7S and 19S immunoglobins belong to distinct classes and (b) that amphibian 7S immunoglobulin does not resemble mammalian IgG or IgA.

Elimination of inter-species reactive anti-IgG antibodies by affinity chromatography

Inter-species reactive anti-IgG antibodies are disturbing in blocking and interference experiments with the sensitive mixed hemadsorption (MH) technique. By affinity chromatography this disturbance could be efficiently eliminated. Anti-IgG sera were passed through columns containing heterologous IgG. The absorption technique is rapid and simple. After one absorption the inter-species reactivity in anti-IgG sera had been decreased thousand-fold, while any loss of species-specific reactivity could not be detected. Such absorbed anti-IgG sera reacted only with homologous antibodies. The effect is exemplified with e.g. blocking of human HLA antibodies by anti-beta2-microglobulin from rabbits.

The neutralization mechanism of Vipera palaestinae neurotoxin by a purified factor from homologous serum

The serum of Vipera palaestinae contains two separate factors which neutralize the hemorrhagic and the neurotoxic activities of its venom. The purified antineurotoxic factor shows one major band in disc electrophoresis and an 800-fold increase in specific activity. Its molecular weight is approximately 56 000 and the isoelectric point is 4.0. These data, together with the failure to form precipitin lines in immuno-diffusion tests, suggest that the antineurotoxic factor of Vipera palaestinae serum is probably an albumin-like or alpha-globulin fraction rather than an immunoglobulin fraction. In vivo experiments show that the neutralizing protein does not protect or block the neurotoxin target sites. When the neurotoxic fraction is injected into mice intravenously at different intervals following injection of the snake serum, the neutralizing activity decreases with time. Experiments carried out in vitro show that the antineurotoxic factor is inactivated upon heating at 95 degrees C for 10 min but resists boiling when mixed with the neurotoxic component, suggesting the formation of a thermostable complex between the two components. This assumed complex dissociates at pH 2.5 and the neurotoxic activity reappears. Further investigation of the reaction with 131I-labeled neurotoxin and neurotoxin components shows that a stable complex is formed between the neutralizing protein and one of the synergistic components of the neurotoxic fraction.

Lymphocyte activation by monovalent fragments of antibodies reactive with cell surface carbohydrates

Antibodies reactive with cell surface carbohydrates were isolated from normal chicken serum and were found to be mitogenic for mouse splenic lymphocytes as assayed by both blast transformation and [3H]thymidine incorporation. The Fab' fragments of these carbohydrate-binding immunoglobulins were just as mitogenic as the divalent native antibody. Moreover, succinylated Fab' fragments, which probably would not form self-associating aggregates, showed similar mitogenic properties. All of these results indicate that, at least for saccharide-specific ligands, multipoint attachment and receptor cross-linkage on the cell to which the ligand is attached may not be a stringent requirement for activation.

Evolutionary and developmental aspects of T-cell recognition

Studies relating to the nature of the antigen-specific T-cell receptor are reviewed in the light of present knowledge of phylogenetic and ontogenetic development. It is suggested that this evidence supports the concept that immunoglobulin (Ig) is the T-cell receptor, and that the following conclusions may be tentatively drawn.

A simple method for producing a monospecific antiserum against IgM

To avoid the chemical purification of mastomys IgM, a reliable alternative method for producing a specific anti-mastomys IgM antiserum was developed. It employs the strong cross-reactivity of antisera against mouse serum proteins with mastomys serum proteins. By the immunoelectrophoresis technique, precipitates of mastomys IgM and cross-reacting rabbit anti-mouse IgM were obtained. A rabbit was immunized with these precipitates. Activity against the light chains was removed from the antiserum by passage over an immunoadsorbent column of mastomys IgG. The adsorbed antiserum was found to be specific for determinants on mastomys IgM.

Bovine Venereal Vibriosis: Variations in Immunoglobulin Class of Antibodies in Genital Secretions and Serum

The immunoglobulin classes of antibodies to Campylobacter (Vibrio) fetus in cervicovaginal mucus (CVM) were determined by the indirect fluorescent antibody test at sequential periods, since the order of class appearance has not been established for specific secretory immune responses. In the local immune response to C. fetus immunoglobulin M (IgM) antibodies appeared first, immunoglobulin A (IgA) antibodies next, and immunoglobulin G (IgG) last. IgM antibodies were quite transient, but IgG antibodies remained longer, and those of the IgA class persisted until the end of the experimental period (up to 10 months). Since differences appear to exist between immune mechanisms at cervicovaginal and uterine sites, as well as between immune responses induced by local and systemic immunizations, the immunoglobulin classes of antibodies in uterine secretions were compared with the classes in CVM and serum. Uterine antibodies arose coincidently with uterine lesions in heifers slaughtered after short periods of infection. In convalescent animals only IgA antibodies were found in CVM, whereas the predominant class of antibodies in the uterine secretions was IgG 1 in three of four animals studied. Only IgG antibodies were detected in CVM and uterine secretions of systemically immunized animals. These findings could account for faster clearance of C. fetus from the uterus than from the cervicovaginal area in locally infected animals and for failure of colonization in systemically immunized animals, because IgG antibodies are good opsonins and IgA antibodies are not. IgA antibodies do immobilize C. fetus , however, so they could prevent recolonization of the uterus in cervicovaginal carriers.

Comparison of antigenicity of hepatoma cells, normal liver cells, foetal liver cells and chemically damaged liver cells in guinea-pigs immunized with hepatomata using the macrophage migration inhibition test

The macrophage migration inhibition test has been used to study the immune responses of guinea-pigs immunized with injections of whole cells of both an allogeneic and a syngeneic hepatoma grown as established cell lines in tissue culture.A clear dose-response relationship between tumour cell concentration and migration inhibition was seen in immunized animals and no significant migration inhibition was seen in control animals. There was no cross reaction between the two tumours used. There was no cross reaction between whole isolated normal liver cells and tumour cells, or between foetal liver cells and tumour cells. Whole isolated liver cells from carbon tetrachloride damaged livers caused some degree of migration inhibition in both normal and immunized guinea-pigs but, taking this into account, they did not appear to cross react with hepatoma cells.

Immediate hypersensitivity responses in flatfish

Fungal extracts that precipitate with human C-reactive protein caused immediate erythema on subdermal injection into marine flatfish. Only species with calcium-dependent serum precipitins to these fungi showed skin reactions. Immediate hypersensitivity in a nonreactive species could be induced after injection with serum from reactive species. The transferable serum factor (or factors) was heat sensitive.

Amino-acid sequence of the variable region of the heavy (alpha) chain of a mouse myeloma protein with anti-hapten activity

Cyanogen bromide cleavage of the heavy (alpha) chain of protein 315 (an immunoglobulin A mouse myeloma protein with anti-dinitrophenyl activity) yielded five fragments of which one (CN2), with 156 residues, contained the chain's entire variable region. Determination of the amino-acid sequence of CN2 showed that: (1) the variable region has appreciable homology (about 33% identities) with the variable region of the light chain from the same molecule; and (2) the constant-region sequence immediately following the probable transition from variable to constant domains is the same in the protein-315 alpha as in human gamma1 and mu chains (-Val-Ser-Ser-). The sequence of the cyanogen bromide octapeptide (CN5) from the carboxy terminus of the protein-315 heavy chain closely resembles the corresponding segments of human alpha and mu chains.

A new mouse immunoglobulin: IgG3

A new subclass of mouse IgG for which we propose the name IgG3 has been shown to have a mol wt of 150,000 consistent with an L(2)H(2) structure, and is present in normal mouse serum at a concentration of 0.1-0.2 mg/ml. Its molecular weight, low carbohydrate content, glycopeptide analysis, and C-terminal analysis are all typical of the IgG class. The intact protein had a strong tendency to form noncovalent aggregates with itself which were dissociable in acid. Upon papain digestion an Fab fragment of 47,000 mole wt was generated along with an Fc fragment which was insoluble at neutral pH. As for its biology, the protein did not fix complement, was not cytophilic for gammaG2 receptor sites on macrophages, and did not show passive cutaneous anaphylaxis. It was very efficiently transported across the placenta so that its concentration in the newborn was twice that in the serum of the mother, compared to the concentration of IgG1 and IgG2 proteins which were only present at one-third the concentration of that found in the serum of the mother. The Fc fragment of this protein reacted with and was solubilized by the staphylococcal A protein which also precipitated the intact immunoglobulin. In addition, the myeloma protein which was the prototype for this gammaG subclass exhibited binding activity for levan which was localized to the Fab fragment.