Lymphoid cells producing antibody against simple haptens: detection and enumeration.

Enumeration of cells producing antibody against arsanilic acid was made feasible by the use of hapten-conjugated sheep erythrocytes for the localized hemolysis-in-gel technique. The time of appearance and numbers of these hapten-specific plaque-forming cells correlated closely with the development of arsanilic acid-specific serum antibodies.

Model-based analysis of CD4+ lymphocyte dynamics in HIV-infected individuals. II. Evaluation of the model based on clinical observations.

The recently developed mathematical model of CD4+ lymphocyte depletion in HIV-infected individuals is evaluated using a comparison with available clinical data. The data used for such an evaluation are to be extrapolated from the published clinical observations as these data sets are not homogeneous covering only parts of HIV infection duration. An additional complication is due to the uncertainty of exact infection onset. Based on these considerations, several different reference data sets are generated from the available clinical data and the range of applicability of the mathematical model and its modifications is then investigated. As a result of such quantitative confrontation, it can be concluded that the appropriate setting of cell interaction parameters in the model can result in a fairly good coincidence of the simulated HIV infection dynamics with reference data sets. Perspectives and limitations of such an approach are also discussed.

Model-based analysis of CD4+ lymphocyte dynamics in HIV infected individuals.

The previously suggested mathematical model of CD4+ lymphocyte depletion in HIV-infected individuals is analyzed and further developed. The model assumes that CD4+ lymphocyte depletion is caused by HIV products. Fairly good simulation of CD4+ lymphocyte dynamics is obtained, when limitation of HIV growth by specific cytotoxic T cells is included in the model. As it is probable that the substantial decrease of CD4+ lymphocytes, this type of influx control mechanism is also included in the model. It is shown that the simulated CD4+ lymphocyte dynamics agree with the observed data, analogously as in the earlier considered case of the constant influx. Moreover, the depleting effect of HIV products on mature and/or immature CD4+ lymphocytes is analyzed by the model. Also, another modification of the model assuming that CD4+ lymphocyte depletion is due to their destruction by cytotoxic T cells specific for HIV antigens, gives simulation results comparable to those obtained by the original version of the model, where the mechanism of the depletion is not specified.

Immunological properties of heterozygous nu/+ mice: changes in antibody response and inducibility of tolerance to protein antigens.

Heterozygous nu/+ mice are not fully identical in their immunological properties with the mice of wild +/+ genotype. A colony of nu/nu, nu/+ and +/+ mice from the same breeding nucleus was established and their immune reactivity to human serum albumin, inducibility of adult immune tolerance to hen egg lysozyme (HEL), sensitivity of their lymphoid cells to stimulation by mitogens and ratio of CD3, CD4 and CD8 positive cell populations was studied. Both the numbers of antibody-forming cells in regional lymph nodes and the antibody titres in sera of nu/+ mice were highly variable, between undetectable values of nu/nu and high values of +/+ homozygotes. Intravenous pretreatment with soluble HEL, leading in +/+ mice to a deep hyporeactivity to subsequent immunization with the same antigen, did not decrease the response of nu/+ mice significantly. These results indicate that the immunological alteration of nu/+ mice is not only quantitative and that T cell subpopulations might be differentially modified by the presence of nu allele. The finding of decreased CD4:CD8 ratio in nu/+ mice also supports this idea.

Effects of interferon gamma on the antibody response to Pseudomonas aeruginosa lipopolysaccharide in mice.

Different strains of mice were examined for the capacity to produce an Ig subclass-specific antibody response to purified Pseudomonas aeruginosa lipopolysaccharide (PALPS). With the exception of the AKR strain, the predominant isotype for most of the strains tested was IgG3 whereas the least frequent isotype expressed was either IgG2b or IgG1. AKR mice were unique in that the predominant isotype produced was IgG2a, rather than IgG3; however, the administration of anti-interferon gamma antibody, at the time of immunization with PALPS caused a substantial decrease in the IgG2a antibody response. Selected B10 congenic strains were used to assess the relationship between the antibody responses and the major histocompatibility complex (MHC) genes. Here, the isotype-patterns for the antibody responses were essentially the same regardless of the MHC haplotype. Interestingly, an increase in IgG2a, with a concomitant decrease in IgM and IgG1 antibody was noted when C3H mice were given interferon gamma at the time of immunization. These studies indicate that, in general, the antibody response to PALPS consists of IgG3 antibody as the predominant isotype, and that the antibody response can be modified by interferon gamma.

The influence of monophosphoryl lipid A (MPL) on erythrocyte autoantibody formation.

The onset and the amount of erythrocyte autoantibodies induced by the injection of C57BL/6N mice with rat red blood cells (RRBC) were hastened and increased, respectively, after the administration of monophosphoryl lipid A (MPL); this was not the case for similarly treated BALB/cAnN mice, which make a lower autoantibody response after immunization with RRBC. The transfer of spleen cells from donor C57BL/6N mice immunized with RRBC suppressed autoantibody formation in recipient mice subsequently immunized with RRBC; however, treatment with MPL prevented neither the induction nor the expression of such suppression. This suggests that the increased autoantibody response in RRBC-immunized C57BL/6N mice treated with MPL is not due to the inactivation of suppressor cell activity which, in other studies, was found to be extremely sensitive to MPL.

Effects of IL-4 depletion on the antibody response to Pseudomonas aeruginosa lipopolysaccharide in mice.

These studies were done to examine the role of interleukin-4 (IL-4) in the generation of isotype specific antibody responses of mice to Pseudomonas aeruginosa lipopolysaccharide (PALPS) by neutralization of IL-4 in vivo using anti-IL-4 antibody (11B11). We found that the administration of anti-IL-4 antibody (11B11) 24 h before immunization with PALPS resulted in a decreased PALPS-specific antibody response for all isotypes examined (IgM, IgG1, IgG2a, IgG2b, IgG3). By contrast, we observed that the non-antigen-specific (polyclonal) IgM response of mice following treatment with 11B11 antibody and PALPS was increased while the polyclonal responses for the other isotypes were unaffected. When mice were given recombinant IL-10 at the time of immunization with PALPS there was a decrease in the PALPS-specific antibody response but an increase in the polyclonal IgM, IgG2a, IgG2b, IgG3 response whereas the polyclonal IgG1 response was decreased by a five-fold margin. The results of these studies suggest that both the antigen-specific and the polyclonal response can be influenced in a different manner by IL-4 or by IL-10.

Immunological unresponsiveness to HSA in chickens.

HSA injected into chickens after hatching induces suppression of anti-HSA antibody formation. Unresponsive chickens react by producing the anti-HSA antibodies earlier and more intensively after BSA challenge than after challenge with HSA. This effect cannot be ascribed to T cells, because they were found to play no substantial role in the unresponsiveness to HSA. Neither was active suppression, which could account for the depressed antibody production, detected. B cell inactivation seems to be the major mechanism involved in this unresponsiveness. However, some additional mechanism must prevent B cells of unresponsive chickens from producing anti-HSA antibodies after HSA challenge, although they are able to form them after immunization with BSA. We suggest that cellular interactions, either between B cells of different specificities or between B cells and macrophages, are responsible for this differential reactivity.

A contribution to mathematical modelling of immunological tolerance.

The original simple mathematical model describing the kinetics of B cell tolerance was extended by the inclusion of Th cell tolerance. It anticipates the existence of two compartments of B and Th cells reactive to the antigen--the immature cells and the mature ones. It is assumed that tolerance is induced by irreversible inactivation of the antigen-reactive cells and the escape from tolerance is due to their differentiation from the precursors. There is also considered the situation, where two categories of Th cells cooperate with the same B cells. Besides that, suppressive activity on Th cells is included in the model. The simulated values are compared with experimental data.

The influence of methylpropionic acid and pyridazinone-3 derivatives on some immunologic and hemopoietic functions.

There was studied the influence on the cell-mediated and humoral response in vivo manifested by selected methylpropionic acid and pyridazinone-3 derivatives which had been found to possess strong immunotropic effects in the in vitro screening previously. It was shown that the compounds were generally poorly tolerated by animals, and they exerted only weak suppressive effects on antibody production, the contact hypersensitivity and survival of skin grafts. This immunosuppressive activity was accompanied by a slight decrease in the number of spleen colony forming cells (CFU-s). Only limited correlation between the biological activity of the preparations and their chemical structure was found.

Effect of proline-rich polypeptide on experimental autoimmune response to erythrocytes.

PRP administration in parallel with RRBC injections increased the AEAP in mice, as did adult thymectomy carried out six weeks before the RRBC injections. On the other hand, PRP administration to thymectomized mice during immunization with RRBC decreased the intensity of AEAP to the level observed in intact, RRBC immunized controls. The number of ARFC among non-B lymphocytes in peripheral blood was increased in mice immunized with RRBC compared to those in non-immunized animals. PRP administration during immunization with RRBC or adult thymectomy lowered their number below the values in non-immune animals and non-B ARFC number comparable to those in control, immunized animals was observed in thymectomized mice injected with PRP in parallel with RRBC. The values of ARFC among the NAL were higher than among the non-B lymphocytes but their shifts in the individual experimental groups were in the same direction as among the non-B lymphocytes. However, their shifts after thymectomy and/or PRP treatment were in opposition to those of the intensity of AEAP in the respective experimental groups.

The effect of thymectomy on immunological tolerance to human serum albumin in chickens.

The effect of thymectomy performed on the day of hatching has been studied in chickens rendered tolerant by 100 mg of HSA injected also on the day of hatching. After challenge at the age of 6 and 9 weeks, no significant difference was observed between the group of tolerant chickens, in which the thymectomy was complete or incomplete, and the non-operated tolerant one. The delayed recovery from tolerance observed in mammals was not seen even in chickens in which thymus was removed completely and no thymic residue remained. The anti-HSA antibodies were even slightly higher in thymectomized birds than in the non-operated ones but the difference was statistically non-significant.

Effect of a proline-rich polypeptide (PRP) on the development of hemolytic anemia and survival of New Zealand black (NZB) mice.

PRP, administered intraperitoneally into NZB mice, twice a week, at doses 0.01-1 microgram per mouse, significantly lowered the incidence of positive Coombs' reaction and prolonged the mean age of the mice. The effect of PRP on survival of mice was better when the treatment with PRP started early (in mice showing first signs of the disease). The results suggest that PRP may induce, from a precursor pool of cells, suppressor cells controlling development of the disease. In addition, the data indicate that PRP may have a therapeutical value in treatment of autoimmune disorders, e.g. the juvenile arthritis.

Oncostatic properties of the complex of bivalent copper with 3-mercapto-2-hydroxypropyl ether of dextran (C-79).

The oncostatic properties of C-79 preparation were examined on the mice with: sarcoma Sa-180, melanoma B-16, Ehrlich carcinoma and leukemia P-388. The preparation was observed to prolong the life of animals with sarcoma Sa-180 and to modulate the morphology of tumors in them. The preparation had no effect on three remaining investigation models. The investigations carried out on mice of AKR strain have revealed that C-79 significantly suppresses the occurrence of spontaneous leukemia, prolonging the mouse survival-time.

Experimental allergic encephalomyelitis in the chicken. Class-specific antibody to myelin basic protein, the ability of T cells to cause GvH reaction, brain and spleen histology, and nonspecific biochemical indicators of inflammation.

Experimental allergic encephalomyelitis (EAE) was induced in chickens by injecting human myelin basic protein (MBP) in Freund's complete adjuvant (CFA). Antibodies of IgM, IgA and IgG class to MBP were measured by enzyme-linked immunosorbent assay (ELISA). The ability of the blood from the experimental chickens to induce graft-versus-host (GvH) reaction was tested in chick embryos. Serum concentrations of sialic acid and antitrypsin were monitored. Substantial inflammatory infiltrations were found in various parts of the central nervous system of the animals injected with MBP, but not in the controls receiving plain CFA. Enlargement of the white pulp and plasmocytosis were found in the spleens of the EAE animals. In the course of the disease, anti-MBP IgM and IgA antibody levels strongly increased, while IgG antibodies remained unchanged. The GvH caused by the blood from EAE animals did not differ from that of control birds. The EAE group showed significantly higher antitrypsin concentration than the controls. The increase in sialic acid concentration was of equal magnitude in the EAE animals and in the CFA controls.

The effect of a proline-rich polypeptide (PRP) on the humoral immune response. II. PRP induces differentiation of helper cells from glass-nonadherent thymocytes (NAT) and suppressor cells from glass-adherent thymocytes (GAT).

Normal mice given thymocyte subpopulations preincubated with a proline-rich polypeptide (PRP) and immunized with SRBC show enhanced or suppressed humoral immune response measured by the number of plaque-forming cells (PFC). PRP induces differentiation of cells exhibiting helper or suppressive function from NAT and GAT respectively. Moreover, it was demonstrated that PRP-induced helper cells lost their activity after treatment with anti-Lyt 1,1 and the PRP-induced suppressor cells after treatment with anti-Lyt 2,1 monoclonal antibodies.

The effect of a proline-rich polypeptide (PRP) on the humoral immune response. I. Distinct effect of PRP on the T cell properties of mouse glass-nonadherent (NAT) and glass-adherent (GAT) thymocytes in thymectomized mice.

It has been shown, using thymectomized, irradiated and reconstituted mice and a proline-rich polypeptide (PRP) that glass-nonadherent thymocytes contain a precursor of helper cell, and glass-adherent thymocytes a precursor of suppressor cells in the humoral immune response to SRBC. Precursor cells differentiate into helper or suppressor cells upon in vitro contact with PRP. Moreover, it was demonstrated that NAT and GAT fractions are related to PNA+ and PNA- thymocytes respectively.

T helper cell inclusion into the mathematical model of immunological tolerance.

The experimentally observed recovery from tolerance to HSA in chickens is much slower than the values calculated by means of the simple mathematical model of B cell tolerance. The model assumes that tolerance is due to elimination or irreversible inactivation of immunocompetent cells reactive to the tolerated antigen, and that the recovery from tolerance is caused by the differentiation of new immunocompetent cells. Even when two collaborating B cell populations reactive to HSA were considered, the calculated recovery from tolerance was much slower than the observed one. Therefore, T helper cell tolerance was suspected and included into the mathematical model. The experimental data agreed best with the calculated values of the recovery from tolerance to HSA obtained with a T cell lifespan of 200 days. On the other hand, when two T helper cell populations cooperated with B cells in anti-HSA antibody production, the curve best fitting the experimental data corresponded to the T cell lifespan of 60 days.

Mathematical modelling of chemotherapy in HIV infection.

A mathematical model of CD4+ lymphocyte depletion in HIV infection is used to simulate and analyse the effect of AZT treatment. In most cases, permanent administration of AZT is observed to stop the CD4+ lymphocyte count decline and to stimulate their increase up to a new steady-state level, which depends on the intensity of AZT treatment, i.e. AZT dose. Temporary administration of AZT leads only to a temporary increase in CD4+ lymphocyte count. After the treatment is terminated, the count starts to decline again. However, the resulting prolongation of patient's survival exceeds the time interval of AZT administration. Interestingly, the survival prolongation is greater, if the treatment is started at five than at two years after the infection and there is no striking increase in survival time if a dose of AZT inhibiting 75% of HIV proliferation is used instead of a lower one inducing 25% inhibition only.

Mathematical modelling of immunotherapy in HIV infection.

The effect of active or passive immunotherapy on HIV infection was simulated using a mathematical model of CD4+ lymphocyte depletion. Permanently effective active immunotherapy increased CD4+ lymphocyte counts to a steady-state level depending on the intensity of the therapy. Active HIV immunization effective for one or more years increased CD4+ lymphocyte counts during the treatment period and prolonged survival substantially; this prolongation exceeded the time interval of therapy duration. Intensive passive immunotherapy by anti-HIV antibodies led to a temporary increase of CD4+ lymphocyte numbers and an apparent prolongation of survival.