Search PubMed⌕ Search

Biomedical subjects

L W Clem

Publications and source records attributed to L W Clem.

At least 91 records · Page 5Linked to original sources
PubMed1984

Immunoglobulin light chain classes in a teleost fish.

Analysis of predominant, approximately 700,000 dalton serum antibody (Ab) of the channel catfish by SDS-PAGE revealed only one molecular mass species of heavy (H) chain (approximately 70,000 daltons), whereas a marked heterogeneity in the relative mobilities of the light (L) chains was evident. Three molecular mass L chain variants of approximately 26,000, approximately 24,000, and approximately 22,000 daltons were observed. The relationships between the L chain variants were not clear until mouse monoclonal Ab (mAb) reactive with catfish immunoglobulin (Ig) were developed. Two of these mAb, designated 3F12 and 1G7, were found to independently recognize different populations of catfish Ig. In addition, when these two mAb were used in combination they immunoprecipitated greater than 95% of specifically purified catfish anti-DNP or anti-fluorescein Ab. The L chains of catfish Ig recovered from immunoabsorbent affinity matrices conjugated with either mAb 3F12 or 1G7 were found to be clearly distinct. Monoclonal Ab 3F12 reacted with a subpopulation of catfish Ig that contained the approximately 24,000 and approximately 22,000 dalton L chain variants, whereas mAb 1G7 reacted with another subpopulation of catfish Ig that contained only the approximately 26,000 dalton L chain variant. Solid phase plate binding assays with the use of mildly reduced catfish Ig H and L chains showed that both of these mAb preferentially reacted with catfish L chains. Subsequent analysis of the two antigenically distinct L chain populations by peptide mapping procedures demonstrated that these L chains were structurally different. Furthermore, analysis of the serum from individual catfish showed the presence of both L chain types in each of 25 catfish examined. These studies strongly suggest that distinct L chain classes have evolved in fish.

Animals↗
PubMed1984

Phylogeny of lymphocyte heterogeneity: the cellular requirements for in vitro mitogenic responses of channel catfish leukocytes.

Cell separation and enrichment techniques were employed to isolate three distinct leukocyte subpopulations present in channel catfish (Ictalurus punctatus) peripheral blood. Surface immunoglobulin-positive (sIg+) and sIg- lymphocytes were separated by an indirect "panning" technique employing monoclonal antibodies reactive with channel catfish Ig. A third cell population composed of macrophages was isolated by adherence to baby hamster kidney cell microexudate-coated surfaces. Functional features of these three subpopulations were assessed by in vitro mitogenic responses to lipopolysaccharide (LPS) and concanavalin A (Con A). The results that were obtained indicated that the sIg+ cells responded only to LPS stimulation regardless of the presence or absence of macrophages. The sIg- subpopulation, however, responded to neither LPS nor Con A unless macrophages were present, in which case responses were obtained to both mitogens. The accessory cell nature of the macrophages was shown by experiments utilizing fixed numbers of one cell type mixed with varying numbers of another cell type. Furthermore, the accessory cell function was abrogated by passage through Sephadex G-10 and preincubation with L-leucine methyl ester. These studies provide further evidence that teleosts not only contain B and T cells akin to those in mammalian systems, but contain accessory cells (macrophages) as well.

Animals↗
PubMed1983

Intramolecular heterogeneity of ligand binding by two IgM antibodies derived from murine hybridomas.

The ligand binding properties of two murine anti-DNP IgM hybridoma antibodies were analyzed. These IgM antibodies, designated NP3-17 C1-20 and SP2/0 I-64 C1-12, each displayed an average of only five high affinity binding sites for the DNP moiety. Reductive 7S subunits of both of these proteins each adsorbed to and were hapten eluted from DNP affinity columns. These subunits, when examined by equilibrium dialysis, each contained an average of one high affinity binding site. Structural analysis of these molecules indicated each to be homogeneous. Results obtained from trypsin hydrolysis of each molecule indicated that differences in conformation of the binding sites may account for the observed binding heterogeneity.

Aminocaproates↗
PubMed1983

Distinctive subpopulations of catfish serum antibody and immunoglobulin.

High molecular weight antibodies and immunoglobulin of the channel catfish were found to be composed of heterogeneous mixtures of covalent subpopulations. Although these proteins appeared tetrameric in physiological buffers (mol. wt approximately 700,000), molecular weight estimates in the presence of the detergent sodium dodecyl sulfate indicated that they dissociated into eight distinct subpopulations. Each dissociative subpopulation was found to be stable under the conditions of electrophoretic analysis, and furthermore each was apparently composed of equimolar H and L chains. Based upon relative mobilities it seems probable that the catfish antibody was composed of various combinations of covalent linkages between covalently-linked H-L chain pairs, i.e. 8, 7, 6, 5, 4, 3, 2 and 1. Further studies suggest the presence of size heterogeneity in catfish light chains. Whether or not this distinction represents isotypic L chain differences is not yet known but these findings coupled with the complex architecture of the physiological tetramer suggest an unusual and previously unappreciated level of complexity present in fish antibody.

Animals↗
PubMed1982

Specificity for tail fibers of a humoral crab factor neutralizing T2 bacteriophage.

It is now becoming clear that invertebrates, animals lacking the ability to make humoral antibodies, are capable of recognizing self from non-self. In several instances this recognition is manifest in normal ("unimmunized") animals by a rapid clearance of certain foreign materials from the circulation One example of such a rapid innate reaction involves the clearance of T2 bacteriophage from the blue crab (1). Other studies have indicated that blue crab plasma contained a factor capable of neutralizing in vitro T2 bacteriophage and hence, by inference, was responsible for the in vivo clearance reaction with this virus (2). The purpose of the work undertaken here was to establish the nature of the specificity of this in vitro neutralizing factor. The strategy involved utilizing purified T2 bacteriophage tail fibers to inhibitthe neutralization of T2 bacteriophage by crab plasma.

Animals↗
PubMed1982

Phylogeny of immunoglobulin structure and function. XIV. Peptide map and amino acid composition studies of shark antibody light chains.

Light chains from antibodies to the streptococcal A-variant carbohydrate from individual nurse sharks were compared by peptide maps of tryptic digests and amino acid compositions. Although the amino acid compositions of the different chains were quite similar, considerable differences as well as similarities were demonstrable on peptide maps. The peptide maps were interpreted as indicating that shark L chains likely have constant and variable regions as seen in the immunoglobulins of higher animals. Furthermore the unique peptides characteristic of different L chains support the hypothesis that nurse sharks, as a species, possess a relatively large number of different L chain amino acid sequences which are compatible with antibody binding sites to the streptococcal antigen. Hence the repetoire of nurse shark antibody combining sites to this antigen appears to be quite extensive.

Amino Acid Sequence↗
PubMed1982

Phylogeny of immunoglobulin structure and function XV. Idiotypic analysis of shark antibodies.

Nurse shark antibodies to the streptococcal A-variant carbohydrate were specifically purified from the sera of four individual animals and used as immunogens in guinea pigs. The resultant guinea pig antisera contained antibodies with apparent idiotypic specificities for the homologous shark proteins. The shark idiotypic sites were located on the Fab fragments and appeared to require the participation of H and L chains for full expression. Tests for cross reactivity employing the four guinea pig anti-idiotypic sera and antibodies from 13 immunized sharks were positive in only two cases (heterologous inhibition). These findings indicate that the idiotypic library (and by inference the antibody combining site repertoire) of nurse sharks to the streptococcal A-variant antigen is probably quite extensive.

Animals↗
PubMed1982

Fish lymphocytes differ in the expression of surface immunoglobulin.

Catfish peripheral blood and splenic lymphocytes were assayed for surface immunoglobulin using fifteen different mouse hybridoma antibodies to catfish immunoglobulin (Ig). These studied showed that this battery of monoclonal antibodies did not detect significant amounts of Ig on all lymphocytes. Unlike polyclonal antisera which demonstrated nearly 100% surface Ig+ cells, the monoclonal antibodies detected approximately 40% surface Ig+ cells. Furthermore, the percentage of Ig+ cells reactive with two of these monoclonals, tentatively shown to react with two different types of catfish light chains, was found to be nearly additive when the two antibodies were mixed. Thus it seems that fish lymphocytes, like their mammalian counterparts, have two different populations of lymphocytes; one which contains abundant surface Ig and one which does not. Whether these two types of cells represent the fish equivalents of B and T cells remains to be determined.

Animals↗
PubMed1981

The molecular mechanism of cryoprecipitation and cold agglutination of an IgM lambda Waldenström macroglobulin with anti-Gd specificity: sedimentation analysis and localization of interacting sites.

The physicochemical properties and immunologic specificity of an IgM lambda cryoglobulin with cold agglutinin activity (designated MAT) were investigated. Discrete binding sites involved in cryoprecipitation were shown to exist on the reductive 7S subunits and tryptic Fab mu and Fc mu 5 fragments derived from MAT. Analytical ultracentrifugation indicated the nonprecipitating MAT subunits self-associated into rapidly sedimenting paucidisperse boundaries of 32S, 25S, and 8.7S at 13 degrees C, which were converted to a monodisperse 5.7S boundary at 35 degrees C. Furthermore, MAT Fab mu and Fc mu 5 fragments exhibited association with each other at 13 degrees C but not at 35 degrees C when studied by analytical ultracentrifugation. The cold agglutinin activity of MAT can be inhibited by sialyllactose or treatment of erythrocytes with neuraminidase but not papain. Therefore, the membrane determinants of human erythrocytes are Gd (glycolipid-dependent or protease-resistant glycoproteins) with terminal sialic acid. Treatment of MAT with neuraminidase abolished its precipitating properties, but had no effect on its ability to agglutinate untreated erythrocytes. The cryoprecipitation and cold agglutination phenomena exhibited by MAT therefore seem to involve identical or cross-reacting carbohydrate antigens with terminal sialic acid residues.

Agglutinins↗
PubMed1981

The metabolic relationships of the immunoglobulins in fish serum, cutaneous mucus, and bile.

Passive administration of homologous, radioiodinated, purified high m.w. (HMW) or low m.w. (LMW) serum immunoglobulin (Ig) into the sheepshead, a marine teleost, showed that the LMW Ig was neither an extracellular precursor nor a degradation product of the HMW Ig. These studies also showed that the half-lives of the HMW and LMW Ig were statistically identical, i.e., approximately 16 days. Furthermore, this work demonstrated that the Ig found in cutaneous mucus and bile were not due to transudation or active transport of either the serum HMW or LMW Ig. The implications of these later findings, coupled with previous physicochemical characterizations of the Ig in fish secretions, support the hypothesis that fish, similar to higher vertebrates, have a secretory immune system.

Animals↗