anti-SRBC Antibody Titers Research Articles

Differential Antibody Responses in 6.B Major Histocompatibility (B) Complex Congenic Chickens

Lines 6.6-2 (B2B2) and 6.15-5 (B2B2), congenic for the major histocompatibility (B) complex with > 99.9% background gene uniformity, were used to examine primary antibody responses to two antigens. In each of two trials, 1 mL of 5% SRBC, a T cell-dependent antigen, or 0.1 mL of Brucella abortus (BA), a T cell-independent antigen, was injected into separate groups of each B genotype aged 3 and 6 wk. Blood samples were taken from the chickens 7 d after immunization. Serum titers (log2) for both total antibody and mercaptoethanol (ME)-sensitive antibody to detect IgG were assayed by microtiter procedures. Least squares analysis of variance and Fisher's protected Least Significant Difference at P < 0.05 were used to evaluate the data. The total anti-SRBC antibody titer was significantly higher in B5B5 chicks than in B2B2 chicks at 4 and 7 w k of age. There was no significant difference in ME-sensitive antibody to SRBC. Chicks of the B5B5 genotype also had significantly higher total and IgG antibody titers to BA at both ages than B2B2 chicks. The results indicate that 4- and 7-wk-old B5B5 chicks had a significantly stronger antibody response to SRBC or BA than B2B2 chicks.

Effect of DTC on Humoral Response of SRBC-Immunized Mice Exposed to Restraint Stress Comparison with Calf Thymus Extract

The studies were conducted on Balb/c mice exposed to restraint stress twice for 12 h at 24 h intervals. Some of the experimental mice were immunized i.p. with sheep red blood cells (SRBC). The antigen was injected before the first exposure of the mice to restraint stress, or immediately after the second loading was ended. Sodium diethyldithiocarbamate (DTC) at a dose of 20 mg/kg or calf thymus extract (TFX) at a dose of 10 mg/kg were injected i.p. four times at 24 h intervals, before or after the exposure to restraint stress. In our experiment restraint stress drastically reduced the number of thymocytes and splenocytes as well as the weight ratio of the thymus and spleen and the changes sustained for 10 days of the observation. Besides, humoral response of the restrained mice to SRBC was deteriorated, as the number of plaque forming cells (PFC) and anti-SRBC antibody titers (total and 2-mercaptoethanol resistant) decreased. The suppressive action of the stress on humoral response was weaker when the antigen injection preceded the first exposure of mice to restraint stress as compared with that observed when antigen stimulation took place immediately after the exposure of mice to stress. It has been found that DTC and TFX administered to mice either before or after the exposure to restraint stress effectively inhibit stress-induced immunosupression. The protective or immunomodulating action of the two drugs is expressed in accelerated and enhanced recovery of the spleen and thymus and in total or partial restoration of the humoral response to thymus-dependent antigen. TFX, administered after the exposure of mice to restraint stress, proves to have a stronger protective and reconstructive impact on thymus, while DTC has a stronger restoring effect on the humoral response dependent on effector T lymphocytes. DTC administered immediately after the exposure of mice to restraint stress results in total restoration of humoral response to SRBC.

Role of dopaminergic mechanisms in the regulation of stress responses in experimental animals

The effects of some dopaminergic agents were evaluated on stress responses in normal and immunized experimental animals. Restraint stress (RS) consistently induced gastric mucosal lesions and elevated plasma corticosterone in rats. Pretreatment with α-methyltyrosine (α-MT), haloperidol, or sulpiride aggravated both responses, whereas bromocryptine attenuated them. In rats immunized with sheep red blood cells (SRBCs), RS prevented the booster-induced rise anti-SRBC antibody titre. This response was further suppressed by α-MT, haloperidol, or sulpiride pretreatment, whereas bromocryptine potentiated the humoral immune response. In mice immunized with SRBCs, antigen challenge-induced increase in footpad thickness was inhibited by RS. Similar inhibitions in this response were also seen after α-MT or haloperidol treatment. The results are discussed in light of complex dopaminergic mechanisms in the regulation of visceral, endocrinological, and immune responses during stress.

Modulation by naltrexone of stress-induced changes in humoral immune responsiveness and gastric mucosal integrity in rats

The effects of restraint stress (RS) and the opioid antagonist, naltrexone, were evaluated on humoral immune responsiveness and gastric mucosal integrity in rats. RS for 24 h, but not 6 h, attenuated both the primary (PAR) and secondary antibody response (SAR) to sheep red blood cells (SRBC) after a single exposure to the stressor. Naltrexone (1 or 5 mg/kg) dose-dependently aggravated the effects of RS on anti-SRBC antibody titre in both PAR and SAR studies. Further, in rats sensitized with SRBC, RS (24 h), in addition to lowering the humoral antibody response, also induced gastric mucosal lesions. Both these responses were further aggravated with naltrexone pretreatment. These results are discussed in light of interactions between immune and visceral responses, and their regulation by endogenous opioids, during RS.

Research Note: Evaluation of Humoral and Delayed Hypersensitivity Responses in Cockerels Reared Under Constant Light or a Twelve Hour Light:Twelve Hour Dark Photoperiod ,

Immature cockerels were reared under constant light [24 h light (L):0 h dark (D)] or a 12L:12D photoperiod in order to evaluate the effect of constant light on immunoresponsiveness. At 10 wk of age males were immunized with SRBC, with reimmunization occurring either 3 or 8 wk later. Animals reared under constant light had lower (P<.05) anti-SRBC antibody titers than the 12L:12D males. Additionally, the pattern of the antibody response following secondary immunizations were different, with 24L:0D males exhibiting no increase in antibody titers between Days 3 and 9 postinjection. Delayed hypersensitivity responses of 24L:0D males were lower (P<.05) than those of 12- or 16-wk-old 12L:12D males. Taken together, these results suggest that circadian light:dark cycles may play a role in modulating the immune system.

Self-stimulation behavior: Consequences upon immunity?

A variety of behaviorial and emotional factors can affect the immune response by changing the brain immunoregulatory mechanisms, resulting in immunosuppression or immunopotentiation. This experiment deals with the effect of chronic self-stimulation behavior on the immune response and lymphoid tissue. Male rats were stereotaxically implanted with bipolar electrodes into the lateral hypothalamus and 7 days after surgery were screened for self-stimulation behavior. Lateral hypothalamus self-stimulating rats (LH-SS) were allowed to self-stimulate for 60 min/day for a period of 9 consecutive days: 5 days before and 4 days after immunization with 5 × 10 9 sheep red blood cells (SRBC). The animals were sacrificed and plaque-forming cell assay (PFC), microhaemmagglutination reaction with SRBC, and differential blood leucocyte counts were performed. The thymus, spleen, and inguinal lymph nodes were weighed and processed for histological examination. In the LH-SS group, an enhanced PFC response and increased anti-SRBC antibody titer were observed when compared to controls. The thymus and spleen of LH-SS rats were smaller in size in comparison with controls, but only with moderate changes in splenic cellular make-up. The relative number of lymphocytes was increased in peripheral blood of LH-SS rats when compared to intact animals. The results obtained suggest that chronic self-stimulation behavior can modulate some parameters of humoral immune response and affect the relative weight of lymphoid organs in the rat.

Short Term Toxicity of Nitrous Oxide on the Immune, Hemopoietic, and Endocrine Systems in CD-1 Mice

Occupational exposures to subanesthetic levels of N2O have been documented to result in suppressed proliferative cell activities. Male CD-1 mice were exposed to 0, 50, 500, and 5000 ppm of N2O for 6 hr/day, 5 days/week for 2 or 13 weeks. Tritiated-thymidine ([3H]-TdR) uptake was measured in CD-1 splenic lymphocytes cultured with and without mitogens and in a mixed lymphocyte culture (MLC). Antibody-mediated immunocompetency was determined for sheep red blood cell (SRBC)-sensitized animals by plaque forming cell (PFC) assay and serum anti-SRBC antibody (Ab) titer. Deoxyuridine suppression tests (dUrdST) were performed on bone marrow cells. There was significantly decreased splenic lymphocyte uptake of [3H]-TdR by cells cultured with mitogenic substances and in MLC following 2-week exposures to 5000 ppm. After 13-week exposures the animals' splenic lymphocytes showed increased [3H]-TdR uptake following high N2O dosing in both the mitogen-induced blastogenesis and MLC assays. Compared to control animals, the 5000 ppm exposure group had significantly depressed PFC activity and circulating anti-SRBC Ab levels following the 13-week N2O exposures, and all 13-week exposure groups demonstrated decreased liver weights and leukopenia. Bone marrow activity at these dosing levels was depressed in a dose-dependent fashion following 13-week gas exposures.

Solid phase enzyme-linked immunosorbent assay (ELISA) for anti-sheep erythrocyte antibody in mouse serum

The solid phase enzyme-linked immunosorbent assay (ELISA) was developed to measure IgM and IgG anti-SRBC antibody titers in mouse serum. Sheep erythrocytes, which have a surface negative charge, were attached directly to the bottom of an aminoplate well (96-well flat bottom, Sumitomo Bakelite Co.) which is charged positively to provide a solid phase for the ELISA antigen. Serum samples titrated were obtained from mice 5 and 10 days after SRBC immunization. Alkaline phosphatase-labeled goat anti-mouse IgM and/or IgG preparations were used as second antibody. Alkaline phosphatase activity in a well was measured by the Kind and King method [Kind, P.R.N. & King, E.J. (1954). J. clin. Path., 7, 322–326]; the optical density (OD) value of quinone as a final product was measured at 492 nm. (1) A linear relationship was observed between the antiserum concentration and OD value over a wide enough dilution range to assay antibody titers of serum samples; (2) IgM and IgG fractions from antiserum showed almost the same antibody titer as did the reconstituted samples; (3) a good correlation was observed between the serum IgM titer and the number of IgM hemolytic plaque-forming cells (PFCs) in spleen 5 days after the immunization, and was also observed between serum IgG antibody titer and the number of IgG PFCs 5 and 10 days after. Therefore, the ELISA described here requires no fixative for preparation of cell-coated plates, and serum IgM and IgG anti-SRBC antibody titers can be measured without any fractionation technique.

Antibody formation after murine injury

To determine the effect of burn injury on humoral immunity, we followed the murine primary and secondary antibody responses to sheep erythrocytes (SRBC), a T-cell dependent antigen, and lipopolysaccharide (LPS), a T-cell-independent antigen, after 25% TBSA burn. Splenic B-cell-specific antibody synthesis was measured by a hemolytic plaque assay. Simultaneous measurements of specific and nonspecific immunoglobulins were performed by a hemagglutination assay and radial immunodiffusion, respectively. Numbers of splenic primary anti-SRBC-plaque forming cells (PFC) were generally equal in burn and control groups. Numbers of splenic secondary IgG anti-SRBC and anti-LPS PFCs were significantly increased in the burn group with a peak at 5 and 16 days after secondary immunization. There were no differences in serum anti-SRBC or anti-LPS antibody titers between burn-injured and control mice. Nonspecific serum IgG levels were depressed on Days 5 and 10 following injury but had returned to normal by Day 10. Due to the discrepancy between increased secondary PFCs and normal or decreased serum immunoglobulin levels, we measured clearance of exogenously administered IgG. The half-life of IgG in burn mice was 2.5 days compared to 7.1 days in control ( P < 0.05). In conclusion, the antibody response is enhanced after burn injury in the mouse, but this is not reflected in serum levels of specific antibody or immunoglobulins probably due to increased clearance from the circulation.

Evaluation of pesticide effects on humoral response to sheep erythrocytes and mouse hepatitis virus 3 by immunosorbent analysis

Effect of selected organochlorine, organophosphorus, and carbamate pesticides on the humoral immune IgM response was examined upon immunization of inbred C57B1/6 mice with neutral, polyvalent, T-dependent sheep erythrocytes (SRBC) and T-independent lipopolysaccharide (LPS). In addition, a pathogenic antigen, mouse hepatitis virus 3 (MHV3) was used for determination for the interaction of selected pesticides on the primary IgG immune response in a model of viral infection, of the genetically resistant A/J mouse strain. Single, sublethal doses of dieldrin, carbofuran, and matacil induced a marked immunosuppression of the humoral responses to both neutral and pathogenic antigens. The data showed that single, sublethal doses (0.4 ≤ LD 50 ≤ 0.6) of dieldrin, carbofuran, and matacil inhibited the number of SRBC-primed cells without any direct cytotoxic effect on the activated plasmocyte, as the titer of specific antibody measured by an enzyme-linked immunosorbent assay (ELISA) per activated cell, was constant. In contrast, exposure to malathion at 10–14 days prior to the assay increased the number of plaque-forming cells (PFC) and the anti-SRBC IgM and anti-MHV3 IgG antibody titer, suggesting therefore an increase in the humoral response to neutral and pathogenic antigens in C57B1/6 and A/J mice. Immunomodulation of the humoral IgM response by selected pesticides was shown to take place at a stage prior to antibody secretion from the activated cell, as the ELISA/PFC index was similar to the control value. The data obtained for dieldrin-induced inhibition of the humoral response to SRBC and LPS antigens suggest a mechanism of immunosuppression common for both T-dependent and T-independent antigens. Good correlations were obtained for the immunomodulatory effects of selected pesticides, as measured by PFC and ELISA, which encourages support for the latter technique in the immunotoxicological screening of pesticides.

Ah receptor mediated suppression of the antibody response in mice is primarily dependent on the Ah phenotype of lymphoid tissue

Halogenated aromatic hydrocarbons act through the aromatic hydrocarbon ( Ah) receptor in mice to produce a series of toxic effects of the immune system. The receptor protein is a product of the Ah gene locus. Ah responsive ( Ah b Ah b ) mice express a high affinity receptor in both lymphoid and nonlymphoid tissues whereas nonresponsive Ah d Ah d mice express a poor affinity receptor. To determine the role of the Ah receptor of lymphoid tissue relative to that of nonlymphoid tissue in the induction of immune impairment, bone marrow was used to reconstitute lethally irradiated mice of the same or opposite Ah phenotype. All mice were given 3,3′,4,4′-tetrachlorobiphenyl (35 and 350 μmol/kg) ip 2 days before immunization with sheep erythrocytes (SRBC). The immune response to this T dependent antigen and organ weights were determined 5 or 7 days later in normal or chimeric mice, respectively. Monoclonal Lyt 1.1 and Lyt 1.2 antibodies were used to establish the origin of the cells which repopulated the chimeric thymuses. The immune responses of both BALB cBy ( Ah b Ah b ) and the BALB cBy × DBA 2 hybrid, CByD2F 1 ( Ah b Ah d ), were significantly suppressed but DBA 2 mice were unaffected. The immune responses of chimeric BALB cBy → BALB cBy and BALB cBy → DBA 2 (donor → recipient) mice were also significantly suppressed and thymic atrophy was observed in both cases. The serum anti-SRBC antibody titers of DBA 2 → BALB cBy chimeras were also significantly decreased although not to the same extent as in BALB cBy → DBA 2 mice. Chimeric DBA 2 → DBA 2 mice were not affected. These results indicate that the sensitivity to Ah receptor mediated suppression of the antibody response is primarily determined by the Ah phenotype of the lymphoid tissue.

The Effect of Environmental Temperature on Immune Response and Metabolism of the Young Chicken. 5. Effect of Low Environmental Temperature on the Humoral Immune Response to Sheep Red Blood Cells in Relation to Energy Metabolism

The effect of low environmental temperature on the humoral immune response to sheep red blood cells (SRBC) was investigated in relation to energy metabolism. Two experiments were done with 3- to 6-week-old pullets using two climate respiration chambers. During both experiments a standard temperature regimen of constant 25 C was maintained in one chamber, whereas the temperature in the other chamber was constant 10 C (Experiment 1) or fluctuated between 5 to 15 C (Experiment 2). The relative humidity was held at 70% at all temperature regimens. Feed allowance was such that growth rates at the two temperatures within experiment were expected to be similar.Indeed, growth rate and body weight were not significantly (P>.05) influenced by temperature in Experiment 1. Feed consumption at 10 C was 32.7% above that at 25 C. At 5 to 15 C feed consumption was 34.1% higher than at 25 C, whereas growth rate was reduced (P<.05) by 8%. At 0 and 10 days after injection, differences in hemagglutinin anti-SRBC antibody titers (log2) between temperatures within each experiment were not significant. The 2-mercaptoethanol resistant (2-MEr) antibody titers 5 days after injection were increased by 26% (P<.05) at 10 C compared to 25 C. The fluctuating low temperature reduced 2-MEr antibody titers 5 days after injection by 19% (P<.05). Differences in total antibody titers 5 days after injection between temperatures were not significant, but they tended to be reduced by low temperatures. No significant thermal effects on plaque forming cell counts and relative weights (percent of body weight) of spleen and bursa of Fabricius were found. Fat gain during the period between day of injection (Day 0) and peak antibody titers (Day 5) was significantly increased at the low temperatures. Thermal effects on protein gain were not significant, but more protein was deposited at 25 C than at the other temperature regimens during this period after injection.

Immunosuppressive effect of Entamoeba histolytica extract on hamsters.

The immune response to sheep red blood cells (SRBC) in mice and hamsters injected with an extract of entamoeba histolytica was studied. Both the primary and secondary immune response, measured by anti-SRBC antibody titers, were unaltered in the mouse, while a significant depression of the primary, but not the secondary, response was observed in the hamster. The effect was greatest when the amebic extract (AE) and SRBC were injected on the same day. The number of anti-SRBC rosettes formed in the spleen cells of hamsters treated with both AE and SRBC on day 0 was measured from days 1-16. The response peaked on day 13, while cells from animals injected with SRBC alone gave a maximal response on day 5. The formation of anti-SRBC rosettes in T-lymphocyte-enriched spleen cells treated with anti-gamma globulin serum and complement was almost abolished for the duration of the experiment. It is suggested that the mechanism responsible for this immunosuppressive phenomenon could involve early interference in the afferent limb of the immune response.

The Effect of Environmental Temperature on Immune Response and Metabolism of the Young Chicken. 3. Effect of Environmental Temperature on the Humoral Immune Response Following Injection of Sheep Red Blood Cells

The effect of environmental temperature on the humoral immune response of pullets following injection of sheep red blood cells (SRBC) was investigated. For this purpose four experiments were performed in two climate respiration chambers. In each experiment a standard temperature regimen of constant 25 C was maintained in one chamber. The temperature regimens in the other chamber were as follows: a constant temperature of 15 C (Experiment 1) and 35 C (Experiment 3) and a temperature, which fluctuated between 10 to 20 C (Experiment 2) and between 30 to 40 C (Experiment 4). Total haemagglutinin anti-SRBC antibody titers at Day 5 after injection were increased significantly (P<.01) a t 10 to 20 C, 35 C, and 30 to 40 C compared to the antibody titers of pullets at 25 C. 2-Mercapto-ethanol resistant antibody titers at Day 5 after injection were increased significantly (P<.05) at 35 C and 30 to 40 C.The effect of feeding level and thermal acclimation on antibody titers was investigated within each temperature regimen. Restricted feeding at low or high temperatures increased antibody titers at Day 5 after injection. Exchange of pullets, just before injection, to low or high temperatures decreased total antibody titers at Day 5 after injection.

Perinatal PCB exposure and its effect on the immune system of young rabbits.

Antibody mediated and cell mediated immune functions of offspring from New Zealand white rabbits fed control chow or chow containing 10, 100 or 250 ppm of Aroclor 1248 (PCB) were assessed. Only those offspring from mothers fed 250 ppm of PCB had a significantly lower contact sensitivity response to 2,4-dinitro, 1-fluorobenzene (DNFB). There was no significant decrease in either the plaque forming cell (PFC) response to sheep red blood cells (SRBC) or serum anti-SRBC antibody titer at any exposure level. Histopathologic examination of the spleen and thymus did not reveal any changes in cellularity that might be associated with immuno-suppression; nor did differential white blood cell counts or mitogen response of peripheral blood lymphocytes to PHA or Con-A differ significantly from controls.

Effect of polychlorinated biphenyls on the immune responses of rhesus monkeys and mice

Female rhesus monkeys were fed either normal chow or chow containing 2.5 or 5.0 ppm of Aroclor 1248 (PCB). After 6 months, the PCB-fed monkeys developed chloracne, alopecia, and facial edema. After 11 months, control and treated monkeys were immunized with sheep red blood cells (SRBCs) and tetanus toxoid (TT). Monkeys fed 5.0 ppm of PCB had significantly lower anti-SRBC antibody titers than controls at only two intervals following primary immunization. Antibody response to TT was not measurably affected by PCB exposure. Both PCB-fed groups had consistently lower γ-globulin levels than controls. These results indicate that sustained exposure to low levels of PCB could have modest to slight immunosuppressive effects, which might be important depending on the general health of the individual. Mice fed up to 1000 ppm of PCB for 3 to 5 weeks exhibited no signs of PCB intoxication other than liver hypertrophy. However, these mice, when challenged with Salmonella typhimurium, showed higher mortality and significantly greater numbers of viable organisms in the spleen, liver, and blood than did controls. Similarly, exposed mice showed an increased sensitivity to endotoxin. Thus, mice exposed to subclinical doses of PCB (i.e., doses insufficient to produce overt clinical signs of intoxication) appear to have an impaired ability to withstand challenge by pathogens and an increased sensitivity to endotoxin.