Immunochemistry最新文献

Immunochemieal cross-reactions between calf lens alpha crystallin and homologous proteins from different vertebrate classes were used for the study of antigenic determinants which, in the evolution of this protein, were derived from common ancestral forms.

Determination of the sequence in which the different antigenic determinants evolved was based on estimation of the relative number of antigenic determinants shared by calf alpha crystallin with alpha crystallin from other vertebrate classes. For this estimation, samples of antiserum to calf lens alpha crystallin were absorbed with homologous lens proteins from each of the different vertebrate classes.

The unabsorbed antiserum reacted with homologous proteins from all vertebrate classes. Each of the absorbed antisera showed a taxonomically different extent of residual cross-reaction. The species used for absorption were then ordered according to an increasing taxonomic extent of residual cross-reactions of the absorbed anti-calf antiserum, indicating a sequence of species with decreasing numbers of antigenic determinants shared with the mammalian protein. This sequence represents the increasing phylogenetic distances between the species used for absorption and the species used to produce the antiserum. This immunochemical determination showed that the phylogenetic sequence in which antigenic determinants present in the calf alpha crystallin molecule were formed, progressed from the primitive aquatic vertebrates agnatha, elasmobranchii and actinopterygii to the primitive land vertebrates and then to amphibia, reptilia, aves and mammalia.

For the estimation of the relative amount (%) of determinants derived from different ancestral forms and transferred in evolution to calf alpha crystallin,¹²⁵I bound to a calf alpha crystallin immunoadsorbent after saturation with total¹²⁵I anti-calf alpha crystallin Fab fragments was compared to¹²⁵I bound to the same amounts of calf alpha crystallin after saturation with¹²⁵I Fab fragments of phylogenetically restricted specificity. Of all antigenic determinants in present-day calf alpha crystallin. approximately 42% were found also in the homologous lamprey protein. These determinants originated with the primitive agnatha which started the vertebrate subphylum 450 million years ago. Only about 15% originated with the mammalia, some 200 million years later, rellecting the slow evolutionary change of this protein molecule.

Oligosaccharide inhibition studies using anti-I Ma (group 1) showed thatdGalβl → 4dGlcNAcβl → 6dGal its βl → O-(CH₂)₈COOCH₃ glycoside and OGR_L1.1 (dGalβl → 4dGlcNAcβl → 6-3,4-dideoxy-hex-3-enitols) were equally active on a molar basis defining the anti-I Ma (group 1) site as complementary todGalβl → 4dGlcNAcβl → OCH₂-. The 1 → 3,1 → 6 compound showed very weak activity, the 1 → 4.1 → 3 and 1 → 3.1 → 3 compounds and the βl → O-(CH₂)₈COOCH₃ glycosides of these three latter compounds were inactive in the range studied. The anti-S XIV site differs from the anti-I Ma site in thatdGalβl → 4dGlcNAcβl → 6dGal was only slightly better thandGalβl → 4dGlcNAcβl → 3dGal and both were only about 1–3 more active thandGalβl → 4dGlcNAc. All compounds were inactive in the amounts available (1–2 μM) with anti-I Step and Nay (group 3), Phi and AJ (group 6) and anti-i Den.

It has been conclusively shown that there are conditions under which mice of H-2^s halotype, previously considered to be nonresponders to the random terpolymer (Glu⁶⁰Ala³⁰Tyr¹⁰)_n, do respond. These T cell dependent responses are associated with all GAT¹⁰ preparations which consist of a mixture of heterogeneous polymers containing varying amounts of the three amino acids and especially tyrosine. Moreover as the above mice respond to the closely related polymers GA, GAL¹⁰ and GAT⁴ but not to GT which is immunosuppressive, GAT¹⁰ can be considered to consist of immunogenic and nonimmunogenic (tolerogenic) molecules, the latter associated with GAT containing glutamyl determinants with high concentrations of tyrosine. It is therefore, suggested that the Ir gene controlling the positive responses against the GAT¹⁰ polymers recognize GA determinants (Ir GA gene). For H-2^s mice immunized with 10 μg the entire GAT¹⁰ preparation is non-immunogenic. However, immunization with 100 μg (in complete Freund's adjuvant) activates both helper and suppressor T cells. Between days 14–21, the balance between these two distinct classes of T cells is in favour of the helper T cells which then results in antibody production. The injections of anti-l-J^s antiserum into SJL mice immunized with 10 μg GAT¹⁰ has accomplished the same effect by elimination of the suppressor T cells (Pierreset al., 1978). These findings indicate that in most immune responses, we are dealing with balances between helper and suppressor T cells rather than absolutes. An unusual ‘complementation’ in responses by F1 mice of H-2^p haplotype has been presented. Although none of the inbred or cogenic strains of mice of H-2^p haplotype respond to GAT¹⁰, of several F1 combinations studied only (B10.P × P) F1 mice have responded to 10–100 μg GAT¹⁰. The nonresponsiveness of P/J mice to MBSA-GAT¹⁰ indicates a possible deficiency in these mice at the B cell level. This, coupled with the responses of the F1 hybrids of two nonresponding parents suggest that we might be dealing with a mechanism of complementation of two nonresponders analogous to that reported on by Munro and Taussig, i.e. complementation of two sites of nonresponsiveness. One site might be a defect in the making of helper factor, which is a T cell defect, and the other might be a defect in the response to helper factor i.e. a B cell defect.

Five synthetic oligosaccharides:

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O-stearoyl dextran coated sheep erythrocytes (OSD-E) were sensitized with increasing amounts of MOPC 104E IgM to give IgM-OSD-E in antigen excess, in equivalence and in antibody excess. These zones were defined operationally by susceptibility of the cells to complement-mediated lysis, and by the number of free Fab regions on the cell-bound IgM. The free Hab regions were measured by ability to (a) bind soluble dextran and (b) to react with and participate in complement-mediated lysis of bystander OSD-E. In antigen excess, complement-mediated lysis is proportional to cell-bound IgM and there are few free Fab regions. In the equivalence zone, complement-mediated lysis reaches a plateau, while the number of free Fab regions becomes significant. Throughout the zone of antihody excess, complement-mediated lysis diminishes while the number of free Fab region increase exponentially. Blocking these free Fab regions with soluble dextran prevents reactions with bystander OSD-E.

he rate of reaction of IgM-OSD-E, in antibody excess, with bystander OSD-E is proportional to reaction temperature and the extent of reaction is proportional to cell concentration.

Conformation of the DNA in a salt-soluble chromatin and in the nucleosome sub-unit was studied in a variety of ionic environments. Precipitation with Mg²⁺ was used as one kind of a probe to indicate the arrangement of the proteins in the complex. Parallel circular dichroic measurements were also made. Three types of DNA conformation have been described: (1) an extended configuration. (2) an intermediate type as observed in the high mol. wt, salt-soluble chromatin and (3) the type seen in the nucleosome sub-unit. Both the chromatin and the nueleosome are pictured as flexible complexes iheir structure being highly dependent on the ionic environment.

The new serological group ofStreptococcus sanguis provisionally ealled “group 10043” has been examined The group specific polysaccharide antigen was isolated and compared serologically and chemically with group H antigen fromS. sanguis strain 13843 and strain NCTC 7868 Challis. The results confirm thatS. sangruis strain 10043 (NCTC 11085, ATCC 29667) contains a new antigen which does not react in anti-group H serum, nor in other grouping sera against groups A through V. The group specific antigen isolated from strain 10043 does not contain rhamnose in contrast to the group H antigen. The new antigen appears to be analogous to the other streptococcal group antigens and to deserve recognition as such. The designation W is suggested for the new group antigen. All three antigens examined contain glucose.