[The capacity of fusicoccin for inducing the synthesis of early interferon].

The response of human and animal cells to the action of fusicoccin (FC), a fungal metabolite with phytohormonal properties, was evaluated. The capacity of FC for inducing the synthesis of early interferon (IFN), supplied into the blood serum of common white mice, and for enhancing the natural cytotoxic activity of human lymphocytes in vitro was established. The metabolism of actively proliferating monocytic leukemia cells J-96 and human ovarian carcinoma cells CaOv, as well as mouse fibroblasts L-929, was found to be inhibited under the in vitro action of FC. The common character of the mechanisms of action of FC and IFN having antiproliferative and immunomodulating activity is discussed.

[Capacity of fusicoccin for inducing the production of early interferon].

The response of human and animal cells to the action of fusicoccyne (FC), a fungal metabolite with phytohormonal properties, was evaluated. As shown by in vitro studies, FC had the capacity to induce the production of early interferon (IFN) in the blood serum of non-inbred white mice and to enhance the natural cytotoxic activity of human lymphocytes. In vitro experiments also revealed that the action of FC inhibited the metabolism of actively proliferating monocytic leukemia cells J-96 and human ovarian carcinoma cells CaOv, as well as mouse fibroblasts L-929. The common character of the mechanism of action of FC and IFN, having well-known antiproliferative and immunomodulating activity, is discussed.

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.

[Level of R-proteins in blood during development of diabetes mellitus]. / Uroven' R-belkov v krovi pri razvitii sakharnogo diabeta.

R-proteins were studied in children with diabetes mellitus and in the risk group. The highest titre of the pattern was found in the children group where diabetes was the first to be detected. Normalization of the R-proteins high titre after insulin therapy was more typical for patients with first detected diabetes as compared with children impaired by the disease within 1-2 years. Content of immunoreactive insulin and titre of R-proteins correlated in the risk group. Estimation of the R-proteins titre simultaneously with other markers may be used for early diagnosis of diabetes mellitus as well as in control of the disease compensation.

[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.

Studies of Fc receptors of heart valve and joint fibroblasts.

Normal human and rabbit sera, and the IgG isolated from them, have been shown by immunofluorescence to react with bovine and human heart valve fibroblasts. Analogous results were obtained with sera of children under the age of 2. Positive reactions were observed also with fibroblasts, chondrocytes and osteocytes of human fetal joint tissues. The reactions are mostly due to monomeric immunoglobulins, since soluble immune complexes give much weaker reactions with the fibroblasts. The reactions are apparently dependent on the presence of Fc receptors on these cells. This conclusion is confirmed by positive reactions with IgG Fc fragments, with pure antibodies to ovalbumin and with human monoclonal IgG. The monoclonal IgG1 possesses the strongest ability to bind with fibroblast Fc receptors. No Fc-IgG receptors have been revealed on the fibroblasts and other structures of the interstitial connective tissue of human and bovine myocardium.

[Differences in the properties of antibodies and natural antiglobulin-homoreactants revealed by the method of human IgG chemical modification]. / Ispol'zovanie metoda khimicheskoi modifinkatsii IgG cheloveka dlia dokazatel'stva razlichiia v svoistvakh antitel i estestvennykh antiglobylinovgp, prealtamtpv.

The naturally occurring antiglobulin factors - homoreactants, contained by human IgG preparations, are inactivated as a result of incubation in a solution of sodium rhodanide (3 - 5 M) and sodium desoxycholate (0.005M). Staphylococcal antitoxin contained by the same human IgG preparations is resistant to the action of the reagents. The data obtained indicate the differences in the structure of homoreactants and antibodies.

[Reactions of normal human and rabbit immunoglobulins with heart valve fibroblasts]. / Reaktsii normal'nykh immunoglobulinov cheloveka i krolika s fibroblastami klapanov serdtsa.

It was demonstrated using the indirect immunofluorescent technique that normal human and rabbit sera, and IgG isolated from them intensively reacted with fibroblasts of human and bovine heart valves. The results obtained with Fab and Fc fragments of IgG sugges that this reaction is due to the Fc region of the IgG molecule and related to the presence of the Fc receptor on fibroblasts of heart valves.

Further studies of the adjuvant properties of homologous IgG split products: mode of action of F(ab')2 and related fragments.

Peptic bivalent and monovalent Fab' fragments as well as F(ab')2 fragment from a purified rabbit anti-DNP antibody were equally effective in enhancement of the immune response to SRBC. In contrast, the papain Fab fragment of normal IgG possessed a considerably lower enhancing activity. These data indicate that the effector site(s) controlling the adjuvant activity of F(ab')2 and related fragments is structurally distinct from the antibody active site(s) within the fragment molecule, and is located in C-terminal region of the heavy chain Fd fragment. When F(ab')2 fragment was injected into rabbits together with the proteinase inhibitor Trasylol it failed to enhance the immune response to SRBC. Furthermore, Trasylol interferes with the ability of F(ab')2 or Fab' fragment to activate the complement system both in vivo and in vitro. This, together with the observation that F(ab')2 fragments enhance the response to T-dependent antigens (SRBC and bovine gamma globulin) but fail to augment the response to LPS, suggests that these fragments may operate via activation of complement and thereby influence indirectly the reactivity of complement receptor B cells.

[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.

[Comparative analysis of the adjuvant action of fab-fragments of normal rabbit IgG obtained using pepsin and papain]. / Sravnitel'nyi analiz ad'iuvantnogo deistviia fab-fragmentov normal'nogo IgG krolika, poluchennykh s pomoshch'iu pepsina i papina

The capacity of Fab fragments of normal rabbit IgG to enhance the immune response to sheep erythrocytes in the homologous recipients was determined by the structure of the C-terminal part of the heavy chain Fd fragment. This followed from the fact that pepsin F(a')2 and Fab' fragments enhanced considerably the hemagglutinin production and proliferation of the antibody-forming cells in the spleen, whereas papain Fab fragments, used in the same dose as the pepsin fragments, possessed only negligible adjuvant activity. As shown the adjuvant activity of pepsin and papain fragments displayed an inverse correlation with the titres and papain homoreactants in the sera of the homologous recipients. The data obtained suggested that the target cells for Fab fragments were lymphocytes carrying cytophilic homoreactants as receptors for the fragments.

Complement - fixation in the interaction of normal rabbit gamma G' globulin and its Fab' fragment.

Complement consumption induced by Fab' fragments of rabbit IgG, irrespectively of their state of aggregation, requires the presence of homologous rabbit IgG. Up to a certain concentration of Fab' fragment, the amount of complement fixed is a linear function of the Fab' fragment dose, but further raising of the Fab'-fragment concentration does not result in complete complement consumption in the sample. The interaction between Fab' fragment and IgG is not strictly species specific.

[Immunochemical properties of naturally occurring antiglobulin factors-homoreactants]. / Nekotorye immunokhimicheskie svoistva estestvenno voznikaiushchikh antiglobulinovykh faktorov--gomoreaktanotov

The naturally-occurring antiglobulin factors to the pepsin fragments of the homologous IgG (homoreactants or agglutinins) present in the human and rabbit sera and gamma-globulin preparations, behaved in Sephadex G-200 gelchromatography as proteins with a molecular weight of approximately 250,000 daltons. It was shown that the human pepsin homoreactant failed to penetrate through the placenta. Since the pepsin homoreactant was absorbed specifically by the insolubilized antibodies against the Fc portion of the IgG molecule, the data obtained could indicate that the homoreactant activity was associated with the IgG molecules of the unusual structure.