Number Of Direct Plaque-forming Cells Research Articles

Interleukin 2 enhances specific and nonspecific immune responses in experimental Chagas' disease.

Mice infected with Trypanosoma cruzi develop an early and profound immunosuppression of responses to heterologous antigens. Recently it has been demonstrated that this immunosuppression is linked, in part, to deficiency in the production of interleukin 2 (IL-2), and that the addition of IL-2 to cultures of normally unresponsive spleen cells from infected mice will restore responsiveness to sheep erythrocytes (SRBC) and enhance parasite-specific immune responses. In the present study, the effect of administration of ultrapure or recombinant IL-2 on immune responses to SRBC and parasite-specific responses in vivo was examined. It was found that a single injection of 1,500 U of IL-2 provided at the same time as SRBC more than doubled the number of direct plaque-forming cells to SRBC and that multiple injections of 1,500 U of IL-2 were no more restorative than a single injection. Anti-SRBC responses of normal mice were unaffected by injection of IL-2. Single or multiple injections of recombinant human IL-2, with and without gelatin, into highly susceptible C3H(He) mice induced greater parasite-specific immunity as reflected by significantly reduced levels of parasitemia and increased longevity. Three injections of 1,500 U each of recombinant human IL-2 on days 10, 14, and 18 was found to be the most efficacious in reducing parasitemia and increasing longevity. Injection of IL-2 with gelatin did not enhance the effect of IL-2 alone.

Changes in immune response to sheep red blood cells during growth of transplantable rat tumor.

The number of direct plaque-forming cells and the titer of circulating hemolytic antibodies were studied at different times after transplantation of Guérin tumor in rats. A stimulating effect was observed 5 days after tumor transplantation. In the terminal stage of tumor development the immune responsiveness was reduced. When irradiated, nongrowing tumor tissue was transplanted, an increased immune response could be observed shortly after transplantation while a loss in immune response did not develop up to the 21st day after transplantation.

“In vivo” effects of acetylsalicylic acid and two ether derived compounds on primary immune response and lymphoblastic transformation

A comparison was performed of acetylsalicylic acid and two ether derivatives (Benorilate and Eterilate) and indomethacin in order to ascertain the in vivo effects on the lymphoblastic transformation and the primary immune response in mice. The humoral response in Benorilate- and Eterilate-treated mice was 40–50% lower than that of the controls, whereas in acetylsalicylic acid-treated mice the response was only 25% inhibited. The number of immunoglobulin synthesizing cells was neither reduced by acetylsalicylic acid nor by its derivatives, although indomethacin treatments (used for comparative purposes) inhibited by 40% the number of direct plaque-forming cells on the days tested. Mitogen-induced proliferation of spleen lymphocytes was also inhibited in the treated mice; these inhibitions were negligible in the case of cells from acetylsalicylic acid-treated mice activatged by concanavalin A and slight in cells from Benorilate-treated mice activated by bacterial lipopolysaccharide. When lymphocytes from drug-treated animals were further cultured in the presence of the same drug, a variable inhibition of mitogen-induced proliferation was observed. These different in vivo effects of acetylsalicylic acid and the two ether derivatives and indomethacin may be due to a distinct action on diverse lymphocyte subpopulations altering their cellular collaborative interactions or modifying the prostaglandin availability.

Different Effects of the Capsular Polysaccharide of Klebsiella pneumoniae on the Functions of Various Subpopulations of B Cells in the Immune Response of Mice to T‐Dependent Antigen

AbstractUsing the capsular polysaccharide of Klebsiella pneumoniae (CPS‐K) as a polyclonal B‐cell activator (PBA) and sheep red blood cells (SRBC) as a T‐dependent antigen, we studied the effects of PBA on the functions of various subpopulations of B cells in the immune response of mice to T‐dependent antigen. Antibody‐forming cells (AFC) of IgM and IgG types were estimated as anti‐SRBC direct and indirect plaque‐forming cells (PFC), and the B cells with precursor activities involving generation of AFC and supplementing new B cells as rosette‐forming cells (RFC) of the B‐cell type. Stimulation of normal mice by CPS‐K caused a definite increase in the number of direct PFC but not in that of indirect PFC and RFC in the spleens. The responsiveness of spleen cells of CPS‐K‐treated mice to generate PFC and RFC responses to a subsequent injection of SRBC was lower than that of CPS‐K‐untreated normal mice. In this case, the responsiveness to generate RFC and indirect PFC was inhibited more strongly by CPS‐K than that to generate direct PFC. When CPS‐K was injected into normal mice simultaneously with SRBC, CPS‐K never decreased but increased the levels of PFC and RFC responses to SRBC. In the spleens of SRBC‐primed mice, the number of RFC was markedly decreased following injection of CPS‐K, the number of direct PFC was increased only slightly and the number of indirect PFC was increased very slightly. The responsiveness of spleen cells of these CPS‐K‐treated SRBC‐primed mice to generate secondary PFC and RFC responses to a subsequent injection of SRBC was much lower than that of CPS‐K‐untreated SRBC‐primed mice. In this case, the responsiveness to generate the secondary RFC and indirect PFC responses was more strongly inhibited by CPS‐K than that to generate the secondary direct PFC response. When CPS‐K was injected into SRBC‐primed mice simultaneously with the secondary injection of SRBC, there were marked decreases in the level of the secondary RFC response and slight decreases in that of the secondary indirect PFC response, but little change in that of the secondary direct PFC response. From these results it has been concluded that CPS‐K provides the positive signal (the minor action) and the negative signal (the major action) to various subpopulations of B cells functioning at various stages of the immune response to T‐dependent antigen in different ways, and acts to regulate the levels of B‐cell responses to the antigen‐mediated positive signal.

Suppression of humoral responses during Trypanosoma cruzi infections in mice.

C57BL/6 mice exhibit low parasitemias and often survive Trypanosoma cruzi infections, whereas C3H(He) mice die during the acute phase with relatively high parasitemias. The present study showed that both strains of mice develop nonspecific immunosuppression to challenge with sheep erythrocytes during the course of infection. Several major differences in immunosuppression-related phenomena between the two strains of mice were determined, yet there is no apparent relationship between immunosuppression and resistance to T. cruzi. Both the number of direct plaque-forming cells and the titer of 2-mercaptoethanol-sensitive agglutinating antibody were significantly lower on day 11 for C57BL/6 mice and day 9 for C3H(He) mice. The number of indirect plaque-forming cells and the titer of mercaptoethanol-resistant agglutinating antibody were reduced by day 36 of infection in C57BL/6 mice and 13 days postinfection in C3H(He) mice. In both strains the degree of humoral response suppression of mice increased concomitant with the period of infection, but was not correlated with the changes in spleen cell numbers. Preliminary experiments designed to explore the mechanism underlying the induction and maintenance of immunosuppression in this hostparasite model disclosed the presence of suppressor substance in the serum of T. cruzi-infected mice. The passive transfer of serum from infected mice to syngeneic recipients elicited a state of immunosuppression to sheep erythrocytes, but did not diminish anti-erythrocyte activity in allogeneic recipients. The induction of immunosuppression in normal mice was further found to be dependent on the interval between serum transfer and challenge with antigen. No quantitative differences existed between the magnitude of suppressed humoral responses in mice infected for varying lengths of time and recipients of serum collected from similarly infected mice.

Alterations in antigen-induced DNA synthesis by specifically localizing cells and other lymphoid cells as a function of immunological memory

The effect of prior immunological experience on the antigen-induced DNA synthesis by specifically localizing cells (SLC) and other cells capable of migrating into lymph nodes (nonspecific cells, NSC) has been studied. Prior immunization with a homologous red cell antigen (sheep red blood cells, SRBC) results in enhanced DNA synthesis, relative to controls pretreated with saline, by NSC but not SLC for the first 48 hr following secondary immunization. By 72 hr both SLC and NSC show markedly reduced DNA synthesis, the SLC showing the greater reduction. Prior immunization with the strongly cross-reacting antigen, ox red blood cells (ORBC), shows a similar but milder effect; prior immunization with the non-cross-reacting antigen chicken red blood cells (CRBC) is without effect, though a similar depression of DNA synthesis by both SLC and NSC occurs 72 hr after secondary immunization with CRBC. In the presence of a concomitant secondary reaction to a non-cross-reacting (CRBC) or very weakly cross-reacting (horse red blood cells, HRBC) antigen, DNA syntheses by SLC-SRBC and NSC are depressed to approximately the same extent, suggesting that the greater depression of DNA synthesis by SLC seen in homologous secondary reactions reflects the additive effects of clonally specific and nonspecific suppressive factors. A comparison of the DNA synthesis by cross-reacting (ORBC) and non-cross-reacting (SRBC) SLC in mice given SRBC following preimmunization with ORBC suggests that “educated” SLC are considerably more resistant to the effects of nonspecific suppressors than “naive” SLC. Passively administered antibody, in concentrations that markedly reduced the numbers of direct plaque-forming cells appearing 72 hr after primary immunization, had no significant effect on DNA synthesis by SLC or NSC.

Toxicity of organotin compounds. III. Suppression of thymus-dependent immunity in rats by di-n-butyltindichloride and di-n-octyltindichloride

To evaluate the functional significance of di-n-butyl (DBTC)- and di-n-octyltin dichloride (DOTC)-induced lymphoid depletion various immune function studies were carried out. The delayed type hypersensitivity reaction, a parameter of cell-mediated immunity was decreased in rats fed 50 or 150 ppm of DOTC for 6 weeks. This decrease was dose-related. Allograft rejection, another cellular immune response, was significantly delayed by DBTC and DOTC. The antibody response against E. coli LPS, probably a T cell-independent antigen, was not affected by DBTC. However, the humoral immune response against sheep red blood cells (SRBC), which needs the co-operation of T helper cells and B cells, was distinctly depressed by DBTC. Hemagglutination and hemolysin titers as well as the number of direct plaque-forming cells against SRBC per spleen were decreased in a dose-related manner by DBTC. The phagocytic capacity of macrophages of rats was not affected by DOTC as was shown in the carbon clearance test. Altered immune functions were never found in mice or guinea pigs exposed to DBTC or DOTC. From this study it is concluded that both DBTC and DOTC induce immune suppression in rats by a selective inhibition of T-lymphocyte activity. Immune suppression was most pronounced in animals exposed to the chemicals during the developmental phase of the lymphoid system.

A Human T-Independent B Lymphocyte Mitogen Extracted from Nocardia Opaca

Nocardia water soluble mitogen (NWSM), a mitogen specific for mouse and rabbit B cells, activates blood, spleen, and tonsil lymphocytes from all the humans tested. Evidence is presented that it acts selectively on human B lymphocytes. B-enriched cells were recovered from anti-Ig-coated Sephadex columns or after elimination of E rosette-forming cells: they were able to incorporate tritiated thymidine when they were cultivated in the presence of NWSM whereas they were not activated by PWM. Conversely T-enriched suspensions did not respond to NWSM although they were able to be stimulated by PHA and PWM. Moreover, the response to NWSM remained unchanged after T cells had been killed by anti-HTLA serum and complement and disappeared after B cells had been killed by anti-HBLMA serum. After stimulation by NWSM, the number of direct plaque-forming cells to HRBC, LPS, and TNP was significantly increased, showing a polyclonal activation of human B lymphocytes. Since no evidence of T cell help for B cell activation has been found, NWSM thus appears to be a T-independent human B lymphocyte mitogen.

Age changes in immune response of rats to repeated injections of different doses of sheep's red cells

The number of antibody-forming cells and the serum antibody titers were determined in adult and old rats after tenfold immunization with “small” (4·108 cells) and “large” (4·1010 cells) doses of sheep's red cells. The antibody (hemolysin and hemagglutinin) titers in the animals of both age groups were found to be either similar in magnitude or higher in the younger adult rats (for hemolysins, in the case of injection of the “large” dose of antigen). The number of direct plaque-forming cells in the spleen of the old animals was greater than in the young adults at all times of immunization, but the number of indirect plaque-forming cells was greater only at the end of immunization. The results are evidence of differences in maturation of the immune response in animals of different ages.

The Effect of a Streptococcus Pyogenes Teichoic Acid on the Immune Response of Mice

Abstract The immunosuppressive activity of glycerol teichoic acid extracts isolated from Streptococcus pyogenes 1-RP41, a group A beta hemolytic streptococcus, has been investigated by measuring the number of direct plaque-forming cells and indirect plaque-forming cells in isolated spleen cells and serum hemolysin titers in mice treated with the teichoic acid. These extracts caused significant suppression of both the IgM and IgG response which was evident at both the organ level and the circulating antibody level. Inhibition of the immune response seemed to be a function of the poly(glycerolphosphate) backbone of the molecule since inhibition of antibody production was still evident when alanyl esters were removed from the teichoic acid polymer. In addition teichoic acid appeared to be functioning at the early processes of antibody production since treatment with the extract after antigenic challenge did not cause significant suppression.

Quantitative and Qualitative Studies on the Primary Antibody Response to Pneumococcal Polysaccharides at the Cellular Level

Abstract The kinetics of the antibody response to purified pneumococcal polysaccharides was studied at the cellular level using the technique of localized hemolysis-in-gel in conjunction with erythrocytes sensitized with immunizing antigen. The overall pattern of the antibody response was similar, with respect to the number of direct plaqueforming cells produced, to that reported for other antigens. However, using antisera specific for various classes of mouse immunoglobulins to characterize the types of specific plaque-forming cells produced, it appears that the antibody response to pneumococcal polysaccharides is exclusively macroglobulin in nature; two types of macroglobulin antibodies, differentiated on the basis of their efficiency in participating in immune hemolysis, are produced. The data suggest that direct plaque-forming cells may represent only 30% to 50% of the total number of antibody-forming cells produced following immunization.