Endogenous fusicoccin-like ligand revealed in higher plants by radioreceptor and radioimmunoassays.

Radioimmuno- and radioreceptor assays were developed for quantitating fusicoccin-like substances in plants. FC-like ligands were found in cultured horseradish roots (70-90 pmol/g) and headed cabbage leaves (9-11 pmol/g). Detection of FC-like ligands in sterile root culture further argues in favour of endogenous fusicoccin representing a new type of phytohormone.

[R proteins as an integral index of the action on the body of industrial allergens in an experiment on white rats]. / R-belki kak integral'nyi pokazatel' deistviia na organizm promyshlennykh allergenov v éksperimente na belykh krysakh.

P proteins were just obtained from white rats and a method to testify them with the help of highly stable anti-P serum was worked out. Normal titres of P proteins are 1:1600 and 1:3200. Different models of sensitisation to the industrial allergens (delivered intracutaneously, by inhalation, into trachea in various doses and concentrations) were used in trials of the method. P protein level appeared to correlate with the sensitisation degree estimated by specific allergy tests. The highest P protein titer is due to the toxic allergic conditions (up to 1:102400), the minimal to sensitization of threshold (up to 1:12800) level. Provocative inhalation test in sensitized rats induced an increase of P protein titer as delayed hypersensitivity was forming.

[The role of A-cells in affecting the immunostimulating effect of F(ab')2-fragments]. / Rol' A-kletok v realizatsii immunostimuliruiushchego deistviia F(ab')2-fragmentov.

The immunoregulatory effect of F(ab')2 fragments on normal rabbit IgG and that preincubated with A-cells from spleen have been compared. Both products were tested for their ability to enhance primary immune response of rabbit spleen cells to SRBC. It was demonstrated that low molecular mass product appeared after F(ab')2 fragments incubation with A-cells at 37 degrees C and possessed immunostimulating activity similar to that of initial F(ab')2 fragments. In addition, it was shown that F(ab')2 reduction to monovalent Fab' fragment with the following alkylation of SH-group abolished the ability of Fab' fragment to enhance the immune response. It may signify that half cystein Fab' fragment residue is essential for processing of the fragment in A-cells and (or) for immune response enhancement.

Virus-induced blast transformation of lymphocytes and its inhibition by F(ab1)2 fragments of human IgG.

Blast transformation of lymphocytes from persons immunized by vaccines against tick-borne Japanese encephalitides, in response to stimulation by homologous viral antigens was studied. 3H-Thymidine incorporation into lymphocytes was completely inhibited by F(ab1)2 fragments of normal human IgG containing no antibody to the viruses examined. A correlation of the inhibitory action of F(ab1)2 fragments on lymphocyte transformation induced by viruses and phytohaemagglutinin was observed.

[Preliminary lymphocyte activation by a mitogen as a condition for demonstrating the ability of the Fab-fragment of normal IgG to inhibit lymphocyte transformation]. / Predvaritel'naia aktivatsiia limfotsitov mitogenom kak uslovie dlia proiavleniia sposobnosti Fab-fragmentov normal'nogo IgG ingibirovat' transformatsiiu limfotsitov.

Peculiarities attending inhibition of the PHA-induced blast-cell transformation of human lymphocytes by F(ab')2 fragment of rabbit IgG were studied. It was shown that the fragment did not affect the intensity of blast-cell transformation if the lymphocytes were preliminarily incubated with the fragment for 24 h at 37 degrees or 4 degrees C and then transferred to the fresh medium containing PHA. However, if the fragment was added to the cells 24 or 48 h following PHA it produced a significant inhibition of the blast-cell transformation. These data may indicate that F(ab')2 fragment interferes with the lymphocyte transformation only when the cells are already activated with PHA.

[Ability of FAB-fragments of normal rabbit and human gamma globulins to suppress human lymphocyte blast transformation induced by phytomitogens]. / Sposobnost' FAB-fragmentov normal'nykh gamma-globulinov krolika i cheloveka podavliat' blasttransformatsiiu limfotsitov cheloveka, indutsirovannuiu fitomitogenami.

Monovalent and bivalent Fab-fragments of normal human or rabbit gamma-globulin suppressed blasttransformation of human lymphocytes induced by phytohemagglutinin and concanavalin A. Peptic F(ab)2-fragments from highly-purified rabbit anti-DNP antibody displayed suppressing activity similar to that of the fragments of normal gamma-globulin. Fab-fragments affected blasttransformation when added to lymphocytes either simultaneously with the PHA or 24 and 48h after the mitogen. The data obtained may indicate that the inhibiting of lymphocyte blasttransformation produced by the gamma-globulin fragments was not caused by their competing with mitogens for the receptors on the target-cell; the Fab-fragment activity was probably determined by the structures located outside the antibody active centre.

[Tyrosine residues in histones. Kinetics of histones F1 and F2A1 nitration by tetranitromethane]. / Tirozinovye ostatki gistonov. Kinetika nitrovaniia gistonov F1 i F2a1.

The kinetics of nitration of tyrosine residues in histones F1 and F2a1 by tetranitromethane has been investigated. At low ionic strength and 30-fold molar excess of nitrating agent the nitration reaction results in fast modification of all tyrosine residues in both histones. At the same time the rates of modification of different tyrosine residues in histone F2a1 are not identical and markedly exceed the rate of N-Ac-OEt-Tyr nitration in a model system. The increase of reaction mixture ionic strength causes an increase of modification rates. The differential UV-absorption spectra of histone F1 obtained by temperature perturbation show an abnormal positive characteristic maximum at 286.8 nm. Analysis of the dependence of nitration rates of tyrosine residues in histones in saline solutions upon the ionic strength and of difference UV-absorption spectra of histones leads to a conclusion that there are specific interactions of definite parts of histone polypeptide chains. These interactions may arise from aggregation of histone molecules.