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Reaginic antibodies to the benzylpenicilloyl determinant (BPO) and ovalbumin (OA) were induced readily in B6D2F1 mice by a single i.p. injection of either 1 or 10 mug of BPO4-OA suspended with 1 mg of Al(OH)3 in 0.5 ml of saline. Administration of conjugates consisting of the hapten coupled to the isologous, nonimmunogenic murine gamma-globulins (MgammaG), i.e., BPO9-MgammaG, BPO11-MgammaG, or BPO12-MgammaG, resulted in complete and specific suppression of the induction of the anti-BPO reaginic antibody response without affecting, however, the level of reaginic antibodies to OA. Further study of the effect of epitope density on the immunologic properties of BPOX-MgammaG revealed that a) the lightly haptenated conjugated, BPO1-MgammaG and BPO2.9-MgammaG, were not immunosuppressive, b) the conjugates, BPO4.3-MgammaG and BPO19-MgammaG, were partially tolerogenic, and c) the heavily haptenated conjugate, BPO31-MgammaG, was nontolerogenic. Moreover, most importantly, the ongoing anti-BPO response in sensitized mice was readily abrogated by either four daily or four weekly injections of BPO9-MgammaG. The immunosuppressive effect of BPO12-MgammaG conjugates was dose dependent, complete suppression being achieved with 200 mug of the tolerogen. The unresponsiveness to BPO of spleen cells from immunosuppressed donors was also maintained in adoptive cell transfer experiments in spite of the additional administration of the immunizing antigen under conditions expected to yield a secondary IgE response. Hence, it is suggested that, with special precautions to prevent unleashing an anaphylactic shock, treatment of penicillin-sensitive individuals with polyvalent conjugates of an appropriate number of BPO groups per human gamma-globulin molecule would constitute a rational immunotherapeutic procedure for the abrogation of the allergic response to BPO.

The availability of safe and effective IgG preparations for replacement therapy for patients with primary disorders of humoral immunity allows almost unlimited doses of IgG to be used. Thus, knowledge of the optimal dose and serum concentration of IgG to be achieved is of practical importance. In a multicenter study of a reduced and alkylated IgG preparation (MISG), it was shown that the MISG was well tolerated and as effective as the intramuscular immune serum globulin (ISG) used for more than 30 years. During the course of this study, we observed that the standard dose of 100 mg/kg/month resulted in a wide range of IgG levels. We began a study using another intravenous IgG preparation to determine whether the variable IgG levels were due to variability in the half-life of IgG in these patients and whether an individualized dose of IgG could be calculated based on the half-life for each patient. The half-life was greatly prolonged, ranging from 26 to 86 days compared with 21 days in normal individuals. However, there was no correlation between the half-life and the serum IgG concentration over the range of concentrations measured. When patients were treated with higher doses of IgG, based on the amount calculated to raise the serum IgG concentration to 200 mg/dl, only 1 patient actually achieved that level and only 3 had a significant increase in the serum concentration despite the higher dose. Failure to achieve the predicted levels could not be explained by a shortened half-life and seemed to be related to increased losses in the early, redistribution, phase. The half-life was not reduced in patients who did achieve higher serum IgG concentrations, suggesting that the half-life is characteristic for each patient and not directly dependent on the serum IgG concentration. However, only modest increases were observed and additional studies using much higher doses of IgG will be necessary before this issue can be settled. Similarly, we did not see an additional benefit in those patients receiving higher doses of IgG, and further studies will be necessary before it can be determined whether higher levels of IgG can reduce the incidence of chronic infections and justify the increased time and expense. The results of the completed study have been published elsewhere [7].

Intravenous gamma-globulin (IVGG) effectively elevates the platelet count of most patients with chronic idiopathic thrombocytopenic purpura (ITP). This study examined whether this effect was related to changes in in vitro immunoglobulin secretion and suppression in coculture. Before treatment, patient in vitro immunoglobulin secretion was less than 50% of the concurrent control in all eight cases and the patients suppressed antibody synthesis in coculture an average of 39%. After treatment, increases in in vitro immunoglobulin secretion and decreases in suppression were closely related to a good response to IVGG therapy as measured both by acute increases in the platelet count (P less than 0.05) and by the long-term outcome from therapy (P less than 0.05). Decreases in platelet-associated IgG correlated with increases in in vitro immunoglobulin secretion (P less than 0.05). Data consistent with the lack of inhibition of in vitro immunoglobulin secretion following IVGG included long-term increases in both serum IgM and IgG (independent of transfused IgG) and maintenance of the percentage of total IgG that was IgG3. T-cell numbers and subsets and lymphocyte proliferation were unaffected by IVGG. IVGG tends to normalize in vitro immunoglobulin secretion and its suppression in those ITP patients with good clinical responses in conjunction with decreased levels of autoantibody. This evidence suggests that good responders to IVGG may have inhibition of antiplatelet antibody production. IVGG does not appear to interfere with normal antibody production.

In subjects with normal immune system injectable gammaglobulins produce unexpected effects: B cells become unable to mature into plasmocytes in vitro when cultured in the presence of pokeweed mitogen. This inhibitory effect seems to be associated with binding of the denatured gammaglobulins to B cell membrane receptors for the IgG Fc fragment (Fc gamma). In addition, injectable gammaglobulins activate a radiosensitive suppressor T cell population without Fc receptors for IgG. Activation of the suppressive function inhibiting of B cells into plasmocytes results from excessive secretion of prostaglandin E2 (PGE 2) by monocytes. We have previously demonstrated that PGE 2 in excess activates certain suppressor T cells. The secretion of PGE 2 by monocytes is thought to be associated with the binding of denatured IgG's to membrane receptors for the corresponding Fc. Activation of suppressor T cells was reproduced in vitro by incubating total T cells or T cells without Fc gamma receptors in the presence of either complete gammaglobulins or of the aggregates they contain. In contrast, preparations deprived of aggregates and F (ab)'2 fragments isolated from gammaglobulins do not produce any detectable activation of suppressor T cells. The results obtained in vitro may not necessarily correspond to the effects of injectable gammaglobulins on humoral response in vivo. We should point out, however, that a fall in plasma IgE levels may be observed in some subjects and that in exceptional cases of IgG and IgA hypergammaglobulinaemia a fall in IgG and IgA has been recorded after gammaglobulin injections.

Of 3533 Rh-negative women who began a pregnancy without detectable Rh antibodies, 62 (1.8%) demonstrated evidence of Rh isoimmunization during pregnancy or within 3 days after delivery. All denied transfusions as well as abortions or previous pregnancies not followed by the administration of Rh immune globulin. Rh isoimmunization during pregnancy or within 3 days after delivery, which will not be prevented by the administration of Rh immune globulin after delivery, is the most important cause of residual Rh isoimmunization. A clinical trial of antenatal administration of Rh immune globulin, initially at 34 weeks's and subsequently at 28 and 34 weeks' gestation, in 1357 Rh-negative pregnant women who were delivered of Rh-positive babies, was effective in preventing the development of Rh isoimmunization during pregnancy or within 3 days after delivery. Antenatal prophylaxis with Rh immune globulin will be necessary if the incidence of Rh isoimmunization is to be reduced to its lowest possible level. Antenatal prophylaxis at 28 weeks' gestation is now an insured service in Manitoba.

To study the effect of treating rabbits with a locally administered noncorticosteroid anti-inflammatory drug, we gave 26 rabbits unilateral subconjunctival injections of 15 mg of indomethacin suspension daily for 16 days, starting one day before the intracorneal injection of the same eye with bovine gamma globulin. We graded the eyes clinically and killed groups of rabbits on postimmunization days 6, 9, 12, and 15. We determined the number of antibody-forming cells in the homolateral cervical lymph nodes, corneas, and uveal tracts and tested the sera, aqueous humor, and vitreous humor for antibodies. Indomethacin-treated eyes showed significantly less inflammatory response, and an insignificantly greater number of antibody-forming cells, than the controls.

A study was made of the effect of different doses of hydroxythiamine on activity of alkaline phosphatase and transketolase in rat spleen and thymus during primary and secondary administration of human gamma-globulin. Immunization of rats significantly raised alkaline phosphatase activity in both organs. Administration of a large single dose of hydroxythiamine (400 mg/kg bw) reduced transketolase activity in the thymus and spleen in both immunized and non-immunized animals and did not change alkaline phosphatase activity in these organs.

Two (0.18%) of 1086 Rh-negative primigravidas or multigravidas treated similarly in all previous pregnancies, who were given a single injection of Rh immune globulin (300 mug) at 28 weeks' gestation and subsequently were delivered of Rh-positive babies, had demonstrable Rh isoimmunization at the time of that injection and must be considered "logistic" failures of antenatal prophylaxis. The remaining 1084 (who were treated again after delivery) had no evidence of Rh isoimmunization at delivery and none of the 512 screened at 6 months after delivery appeared to be immunized. If the 28th-week injection had not been protective, one would have expected 14 of the 1084 to have been demonstrably Rh isoimmunized and evidence of Rh isoimmunization to have persisted in 6 of the 512 observed 6 months after delivery.Six of 719 Rh-negative multigravidas who had not received Rh immune globulin after previous pregnancies or had been treated only after delivery showed evidence of Rh isoimmunization despite a single injection of Rh immune globulin at 28 weeks in a subsequent pregnancy. In three of the six the cause was most likely "sensibilization" due to previous exposure to Rh-positive blood or an untreated Rh-positive pregnancy. in 3 of the remaining 716 (0.42%) there may have been true failure of antenatal Rh prophylaxis administered at the 28th week. One would have expected this figure to be 12 of 716 if antenatal Rh prophylaxis at 28 weeks' gestation were totally unsuccessful.It is concluded that a single intramuscular injection of Rh immune globulin, 300 mug, is 88% effective in preventing Rh isoimmunization during pregnancy in Rh-negative primigravidas and in multigravidas treated antenatally in all previous pregnancies, and is 75% effective in preventing Rh isoimmunization in Rh-negative multigravidas untreated during previous pregnancies. The majority of failures are due to Rh isoimmunization during pregnancy prior to antenatal prophylaxis at 28 weeks.

Antigen persistence and serum antibody production in intact Xenopus were monitored using human gamma globulin (HGG), in adjuvant, in various immunisation schedules. Retention of HGG in spleen and serum was directly related to the quantity injected. However, antibody responses to a dose range between 1 mu-g-6 mg antigen were similar in intensity. These were detected in the serum two weeks after injection and at this stage were exclusively mercapto-ethanol (ME) sensitive; ME-resistant antibodies had appeared by four weeks. No antibodies were detected below a dose of 100 ng HGG. The effect of splenectomy on antibody levels was tested using HGG/adjuvant or sheep erythrocytes (SRBC) in saline. Splenectomised toads showed impairment of antibody responses only to threshold doses of HGG (100 ng) but to a wider range of SRBC doses.

The ontogeny of the humoral immune response to a 'thymus dependent' and a 'thymus independent' antigen, human gamma globulin (HGG) and Aeromonas salmonicida (AS) respectively, was investigated in the fry of rainbow trout, Salmo gairdneri, by direct immersion vaccination in the antigens (dose 5 mg/L HGG; 10(8) cells/ml AS; 30 minutes) at known ages/weights from 7 days post hatch, and at 1, 2, 3, and 4 months post hatch. Half the fry in each group were tested for antibodies 4 weeks after vaccination, the remainder were reimmunised and tested again after a further 4 weeks. Appropriate controls to test for tolerance induction and memory responses were included. The results indicate that fry are capable of mounting a humoral immune response very early in ontogeny. There is a period of 'unresponsiveness' which persists for longer against HGG, than against AS, though it was not thought to be tolerance as such. Memory could be detected to HGG in fry given a first immunisation at 2 months. The results are compared with preliminary experiments in which fry were first thymectomised 4 weeks before the first immunisation. In fry thymectomised at 1 month post hatch, and tested for primary and secondary responses at 2 and 3 months, the primary response to HGG is unaltered, but the secondary response is reduced. Both the primary and secondary response to AS is unaltered. When thymectomy is performed later, the effect on the secondary response to HGG is no longer apparent, but the primary response to AS is slightly reduced.

A controlled clinical trial was carried out to test the effectiveness of a comparatively low dose of anti-D immunoglobulin (250 mug) in preventing rhesus immunization.In the control group 17 out of 329 women (5%) formed rhesus antibodies, whereas in the treated group only 3 out of 333 women (0.9%) showed active immunization, all three of whom had an exceptionally large transplacental bleeding.

In response to a second injection of rabbits with a dinitrophenylated antigen, given 2 months to 2 yr after the first injection, there was rapid synthesis of large amounts of antibody high in relative affinity for the dinitrophenyl (DNP) determinant. The antibodies formed 3 days after restimulation were already high in affinity. Amounts of antigen too small to elicit detectable antibody production may prime the animal for a partial secondary response characterized by the formation of antibody of intermediate affinity after a second antigenic stimulus. Investigations into the specificity requirements for the secondary response indicated that variation in the carrier protein and in the haptenic determinant could be tolerated. Thus, after immunization with DNP-bovine gamma-globulin, DNP-hemocyanin elicited the vigorous production of high affinity anti-DNP antibodies. However, DNP serum albumin was much less effective: it elicited a secondary response in some animals primed with DNP-bovine gamma-globulin only when the interval between injections was increased from 10 to 28 wk. A secondary response was also evoked when the haptenic determinent of the second immunogen differed slightly from that of the one injected initially (i.e., 2,4,6-trinitrophenyl versus 2,4-dinitrophenyl).

A study of the incidence of Rh-sensitization showed a 6.5% incidence of anti-D appearing for the first time during the last trimester of pregnancy. In 24 of the 29 subjects these antibodies were weak, and were found only when a sensitive technique using enzyme-treated Rh-deletion test cells was employed. The remaining five, however, had high-titre antibodies, which were associated with a positive Coombs test on cord blood.Rh-immune globulin administered at delivery resulted in disappearance of the anti-D in all but one of the subjects with weak antibody to whom it was given, suggesting that this treatment can reverse early sensitization. There was no effect when Rh-immune globulin was given to one subject with a high anti-D titre.Since sensitization has been found to occur frequently during the last trimester of pregnancy, an antenatal schedule of prophylaxis is advocated.