Individual patient variations in the kinetics of intravenous immune globulin administration

Outcomes of X-Linked Agammaglobulinaemia Patients

BACKGROUND

X-linked agammaglobulinaemia (XLA), caused by mutations in BTK, is characterised by low or absent peripheral CD19 + B lymphocytes and agammaglobulinaemia. The mainstay of treatment consists of immunoglobulin replacement therapy (IgRT). As this cannot fully compensate for the immune defects in XLA, patients may therefore continue to be at risk of complications.

OBJECTIVES

To describe the clinical outcomes of XLA patients in the United Kingdom and Hong Kong and evaluate current treatment strategies.

METHODS

Patients with a definitive diagnosis of XLA were included in this cross-sectional and retrospective analysis of clinical health outcomes. Data pertaining to diagnosis, infection incidence, IgG trough levels and lung function were collected and analysed.

RESULTS

99 patients with a median age of 29.02 years (IQR 12.83-37.41) and a total follow up of 1922 patient years, were included this study. The median age at diagnosis was 3.30 years (IQR 1.04-8.38) which decreased over time (p = 0.004). 40% of the cohort had radiological evidence of bronchiectasis. Risk of bronchiectasis was not significantly associated with clinical infection incidence (p = 0.880) or IgG trough levels (p = 0.407). Two patients demonstrated novel complications, namely persistent norovirus infection, leading to haemopoietic stem cell transplantation (HSCT).

CONCLUSIONS

Despite modern therapy, most XLA patients continue to experience complications, most notably bronchiectasis, likely due to absence of IgA/M in current therapies, but lack of B lymphocytes may also lead to additional sequalae. These data strongly support the need for further research, particularly that of curative modalities including HSCT and gene therapy.

Demonstration of Gut-Barrier Dysfunction in Early Stages of Non-alcoholic Fatty Liver Disease: A Proof-Of-Concept Study

BACKGROUND/AIMS

Gut-barrier dysfunction is well recognized in pathogenesis of both non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD). However, comparison of components of this dysfunction between the two etiologies remains unexplored especially in early stages of NAFLD.

METHODS

Components of gut-barrier dysfunction like alterations in intestinal permeability (IP) by lactulose mannitol ratio (LMR) in urine, systemic endotoxemia (IgG and IgM anti-endotoxin antibodies), systemic inflammation (serum tumor necrosis factor alpha [TNF-α] and interleukin-1 [IL-1] levels), tight junction (TJ) proteins expression in duodenal biopsy and stool microbiota composition using Oxford Nanopore MinION device were prospectively evaluated in patients with NAFLD (n = 34) with no cirrhosis, ALD (n = 28) and were compared with disease free controls (n = 20).

RESULTS

Patients with ALD had more advanced disease than those with NAFLD (median liver stiffness -NAFLD:7.1 kPa [5.9-8.9] vs. ALD:14.3 kPa [9.6-24], P < 0.001]. Median LMR was significantly higher in NAFLD and ALD group when compared to controls (NAFLD 0.054 [0.037-0.17] vs. controls 0.027 [0.021-0.045] (P = 0.001)) and ALD 0.043 [0.03-0.068] vs. controls 0.027 [0.021-0.045] (P = 0.019)]. Anti-endotoxin antibody titer (IgM) (MMU/mL) was lowest in NAFLD 72.9 [3.2-1089.5] compared to ALD 120.6 [20.1-728]) (P = 0.042) and controls 155.3 [23.8-442.9]) (P = 0.021). Median TNF-α (pg/mL) levels were elevated in patients with NAFLD (53.3 [24.5-115]) compared to controls (16.1 [10.8-33.3]) (P < 0.001) and ALD (12.3 [10.1-42.7]) (P < 0.001). Expression of zonulin-1 and claudin-3 in duodenal mucosa was lowest in NAFLD. On principal co-ordinate analysis (PCoA), the global bacterial composition was significantly different across the three groups (PERMANOVA test, P < 0.001).

CONCLUSION

While remaining activated in both etiologies, gut-barrier dysfunction abnormalities were more pronounced in NAFLD at early stages compared to ALD despite more advanced disease in the latter.

Immunoglobulin use in immune deficiency in the UK: a report of the UKPID and National Immunoglobulin Databases

Supply of immunoglobulin in the UK faces pressures due to increasing demand, cost and variable supply. This paper describes immunoglobulin replacement therapy (IGRT) in primary immunodeficiency (PID) and secondary immunodeficiency (SID) to assist in the ongoing planning of UK immunoglobulin provision. A retrospective analysis of the National Immunoglobulin Database and the UKPID registry was carried out. In total, 3,222 patients are registered as receiving IGRT for immunodeficiencies. Predominately antibody disorders made up the largest diagnostic category (61% of patients). The total cost of IGRT for immunodeficiency for 2015/16 was £40,673,350; an average annual cost of £1,099,254 per centre and £12,124 per PID patient. SCIg accounted for 43.8% and 50.1% of IGRT, with home therapy accounting for 42.7% and 57.5% of place of therapy in the National Immunoglobulin Database and UKPID registry respectively. In 2015/16 use of immunoglobulin in SID increased by 24% over the previous financial year. The overall trends of increasing demand in immunology are mirrored in other specialties, most notably neurology and haematology. These data are the first national overview of IGRT for immunodeficiencies, providing a valuable resource for clinicians and policy makers in the ongoing management of UK immunoglobulin supply.

Pharmacokinetics and Pharmacodynamics of Intravenous Immunoglobulin G Maintenance Therapy in Chronic Immune-mediated Neuropathies

The regimen for IVIg maintenance treatment varies considerably between patients with chronic immune-mediated neuropathies. Although it is widely recognized that treatment regimens should be improved, detailed pharmacokinetics (PK) of IVIg have not yet been established. We aimed to determine the PK of IVIg maintenance treatment in patients with clinically stable, treatment-dependent, chronic immune-mediated neuropathy. Patients received a median IVIg dose of 30 g (range, 15-70 g) every 14 days (range, 7-28 days) resulting in high IgG peak levels (median, 25.9 g/L; range, 16.7-41.0 g/L) and trough levels (median, 16.1 g/L; range, 9.7-23.6 g/L). IgG PK parameters, including half-life (median, 23.1 days; range, 11-60 days), were constant during subsequent courses in the same patients, but varied considerably between patients. The IgG levels at 1 week after infusion correlated with grip strength. These results provide insight into the PK of IVIg maintenance treatment in patients with chronic immune-mediated neuropathies.

Intravenous immune globulin and thromboembolic adverse events in patients with hematologic malignancy

In patients with hypogammaglobulinemia secondary to chronic lymphocytic leukemia (CLL) or multiple myeloma (MM), intravenous immune globulin (IVIg) may be administered to reduce the risk of infection. Since 2013, IVIg products have carried a boxed safety warning about the risk of thromboembolic events (TEEs), with TEEs reported in 0.5% to 15% of patients treated with IVIg. In this retrospective cohort study of older patients with CLL or MM identified from the Surveillance, Epidemiology, and End Results-Medicare Linked Database, we assessed rates of clinically serious TEEs in 2724 new users of IVIg and a propensity-matched comparison group of 8035 nonusers. For the primary end point, arterial TEE, we observed a transient increased risk of TEE during the day of an IVIg infusion and the day afterward (hazard ration = 3.40; 95% confidence interval [CI]: 1.25, 9.25); this risk declined over the remainder of the 30-day treatment cycle. When considered in terms of absolute risk averaged over a 1-year treatment period, the increase in risk attributable to IVIg was estimated to be 0.7% (95% CI: -0.2%, 2.0%) compared with a baseline risk of 1.8% for the arterial TEE end point. A statistically nonsignificant risk increase of 0.3% (95% CI: -0.4%, 1.5%) compared with a baseline risk of 1.1% was observed for the venous TEE end point. Further research is needed to establish the generalizability of these results to patients receiving higher doses of IVIg for other indications.

Vaccines and Kawasaki disease

The distinctive immune system characteristics of children with Kawasaki disease (KD) could suggest that they respond in a particular way to all antigenic stimulations, including those due to vaccines. Moreover, treatment of KD is mainly based on immunomodulatory therapy. These factors suggest that vaccines and KD may interact in several ways. These interactions could be of clinical relevance because KD is a disease of younger children who receive most of the vaccines recommended for infectious disease prevention. This paper shows that available evidence does not support an association between KD development and vaccine administration. Moreover, it highlights that administration of routine vaccines is mandatory even in children with KD and all efforts must be made to ensure the highest degree of protection against vaccine-preventable diseases for these patients. However, studies are needed to clarify currently unsolved issues, especially issues related to immunologic interference induced by intravenous immunoglobulin and biological drugs.

Evidence for metabolic endotoxemia in obese and diabetic Gambian women

OBJECTIVE

Emerging evidence from animal models suggests that translocation of bacterial debris across a leaky gut may trigger low-grade inflammation, which in turn drives insulin resistance. The current study set out to investigate this phenomenon, termed 'metabolic endotoxemia', in Gambian women.

METHODS

In a cross-sectional study, we recruited 93 age-matched middle-aged urban Gambian women into three groups: lean (body mass index (BMI): 18.5-22.9 kg m(-2)), obese non-diabetic (BMI: 30.0 kg m(-2)) and obese diabetic (BMI: 30.0 kg m(-2) and attending a diabetic clinic). We measured serum bacterial lipopolysaccharide (LPS) and endotoxin-core IgM and IgG antibodies (EndoCAb) as measures of endotoxin exposure and interleukin-6 (IL-6) as a marker of inflammation.

RESULTS

Inflammation (IL-6) was independently and positively associated with both obesity and diabetes (F=12.7, P<0.001). LPS levels were highest in the obese-diabetic group compared with the other two groups (F=4.4, P<0.02). IgM EndoCAb (but not total IgM) was highly significantly reduced in the obese (55% of lean value) and obese diabetic women (30% of lean; F=21.7, P<0.0001 for trend) compared with lean women.

CONCLUSION

These data support the hypothesis that gut-derived inflammatory products are associated with obesity and diabetes. Confirmation of these findings and elucidation of the role of the microbiota, gut damage and the pathways for translocation of bacterial debris, could open new avenues for prevention and treatment of type 2 diabetes.

Serum IgG levels in IV immunoglobulin treated chronic inflammatory demyelinating polyneuropathy

OBJECTIVE

To determine the variability of serum IgG in patients with chronic inflammatory demyelinating polyneuropathy (CIDP).

METHODS

All 25 CIDP patients had active but stable disease and were treated with individually optimised fixed dose IVIg regimens. IgG was measured by turbidimetry and variability was defined as coefficient of variation (CV).

RESULTS

The intra-patient variability of the pre-treatment IgG levels, post-treatment levels and increase in serum IgG shortly after IVIg (ΔIgG) was low (mean CV=3%, 4%, 10%). The inter-patient variability between patients treated with the same dose and interval was low in pre-treatment, post-treatment and ΔIgG level (mean CV=13%, 11%, 20%). The ΔIgG levels were associated with IVIg dosage (rs=0.78, p<0.001).

CONCLUSIONS

Clinically stable CIDP patients show a steady-state in serum IgG after serial IVIg infusions. The low intra- and inter-patient variability in IgG may indicate that constant levels are required to reach this stability.

Pharmacokinetics of Intravenous Immunoglobulin: A Systematic Review

BACKGROUND

Intravenous immunoglobulin (IGIV) is used in the treatment of a wide variety of immune disorders. To our knowledge, no comprehensive or systematic review on the pharmacokinetics of IGIV has been published despite the availability of many published individual studies.

OBJECTIVE

To systematically review published studies of the pharmacokinetics of IGIV.

METHODOLOGY

We conducted a search of PubMed/MEDLINE from January 1966-September 2005 and EMBASE from January 1980-September 2005 for English-language articles on the pharmacokinetics of IGIV. This search was supplemented by a bibliographic review of all relevant articles.

RESULTS

Data elements extracted from these articles included study design, number of study subjects, indication for IGIV therapy, IGIV treatment regimen (formulation, dosage, and duration), pharmacokinetic parameters (clearance, volume of distribution, elimination rate constant, and half-life), analytic methodology, pharmacokinetic model, and blood sampling times. The United States Preventive Services Task Force rating scale was used to categorize the 50 pertinent citations identified in our literature search. According to the rating scale, 12 studies were level I (prospective, randomized, controlled studies), 3 were level II-1 (prospective, nonrandomized, controlled studies), 30 were level II-2 (prospective, nonrandomized, uncontrolled [cohort] studies), and 5 were level III (case reports or descriptive studies).

CONCLUSION

The pharmacokinetics of IGIV shows considerable intra- and interpopulation variability among patients with normal immunoglobulin levels, patients with primary immunodeficiency diseases, bone marrow transplant recipients, patients with immune deficiency due to chronic lymphocytic leukemia or multiple myeloma, very low birth weight neonates, neonates with suspected sepsis, high-risk infants in the neonatal intensive care unit, high-risk infants with cardiopulmonary disease, children with cryptogenic West or Lennox-Gastaut syndrome, women and infants with fetal alloimmune thrombocytopenia, and women with recurrent spontaneous abortions. Despite the large number of studies characterizing the pharmacokinetics of IGIV, major literature gaps include lack of information on IGIV clearance or area under the curve parameters and target serum immunoglobulin G concentrations. Further study is needed to rigorously characterize the pharmacokinetic properties of IGIV in a range of patient populations.

Unusual persistence in healthy volunteers and ill patients of hyperimmune immunoglobulin directed against multiple Pseudomonas O-chain and Klebsiella serotypes after intravenous infusion

Persistence of intravenous (i.v.) hyperimmune immunoglobulin (100 mg/kg) directed against clinically predominant serotypes of Pseudomonas and Klebsiella in ill, febrile patients was compared to healthy volunteers to determine if ill patients have a decreased Ig half-life resulting in an increased immunoglobulin requirement. Type-specific antibodies were measured by ELISA for 83 days in eight healthy volunteers and for 35 days in eight ill patients with surgical complications or hematologic malignancy. Mean values and fold rises of antibody concentrations for the two groups were above preinfusion values at 35 days. The antibody fold rises in patients and in healthy volunteers were similar. Type-specific antibody levels in some patients increased after illness coincident with elevation of total immunoglobulins. We conclude that the duration of potentially therapeutic levels of infused type-specific hyperimmune immunoglobulin may persist for a longer period of time than what has been measured for total immunoglobulin. While the mechanism of this persistence remains to be characterized, the possibility of type-specific antibody synthesis induced by immunoglobulin administration must be considered.

Use of intravenous immunoglobulin to prevent or treat infections in persons with immune deficiency

Intravenous immunoglobulin (IVIG) concentrates were originally developed as replacement therapy for individuals with primary deficiencies of the immune system. However, in various well-designed, controlled clinical trials, the ability of IVIG to prevent and possibly treat infections in patients with secondary immune deficiencies has also been considered. In this review, we briefly consider these different applications and suggest whether the data are sufficient to employ IVIG in these clinical settings.

Intravenous immune globulins. A review of their uses in selected immunodeficiency and autoimmune diseases

Intravenous immune globulin (IGIV) was introduced a decade ago as a therapy for primary immunodeficiency diseases. It proved to be a valuable therapeutic substance for this purpose and is now considered to be the treatment of choice. The intent was to supply ubiquitous anti-infectious agent antibodies through passive immunisation to replace deficient circulating antibody content. During such therapy, unexpected benefits were noted in thrombocytopenic patients. Since that time, the therapeutic indications for IGIV infusions have greatly increased, with a particular interest in infectious, haematological and autoimmune diseases. This review summarises the status of IGIV therapy in haematological diseases within the categories of primary immunodeficiency diseases, secondary immunodeficiency states and autoimmune syndromes. The majority of firm data have been gathered on the treatment of patients with primary immunodeficiency disease. These data are reviewed from the aspect of anticipated therapeutic response and side effects. Emphasis should be placed on the IgG circulating blood levels as there is a need for individualizing therapy because of marked interindividual patient variation. The use of IGIV therapy in primary and secondary immunodeficiency states should consider the potential benefits to be attained in haematological malignancies and related complications which may be magnified by chemotherapy and radiation therapy. The mode of action of IGIV in autoimmune diseases, although not yet precisely determined, may involve establishing reticuloendothelial blockade or immunomodulation by supplying anti-idiotype antibodies.

Clinical use of immune serum globulin as replacement therapy in patients with primary immunodeficiency syndromes

IVIG is the definitive therapy for primary immunodeficiency diseases associated with hypogammaglobulinemia or specific antibody deficiencies. Administration of IVIG is relatively safe, but occasional adverse reactions are usually self-limited and generally are not an indication for stopping therapy. Home administration of IVIG has found increasing favor among treating physicians and their patients.

Pharmacokinetics of intravenous immunoglobulin in neonates

Intravenous immunoglobulin (IVIG) may be a therapeutic adjunct to antibiotic treatment of neonatal infections. We examined the pharmacokinetics and safety of IVIG in human neonates. Thirty neonates with suspected sepsis were randomly assigned either to a treatment (receiving either 250, 500, or 1,000 mg/kg of IVIG plus antibiotics) or control (antibiotics alone) group. The 500 mg/kg dose produced a rise in total IgG for greater than 8 and in group B streptococcus (GBS) type-specific IgG for greater than 4-14 days. The type-specific antibody elevation varied with the amount of pathogen-specific antibody and dose of IVIG. Pharmacokinetic analysis suggests a Vdss of 42 ml/kg, Cl of 3.0 ml/kg/day, a biphasic elimination curve, and a terminal elimination half-life of 24.2 days. No toxicity was observed. These data may be valuable in determining optimal dosing schedules for IVIG in treating or preventing neonatal infections.

Clinical use of a new pH 4.25 intravenous immunoglobulin preparation (gamimune-N)

A multicentre, randomised, double-blinded, cross-over study was done to evaluate the clinical use and safety of a new immunoglobulin preparation for intravenous use (IVIgG). This reagent, IVIgG pH 4.25, was compared to a standard commercially available preparation IVIgG pH 6.8. Thirty-nine patients with primary immunodeficiency disease received a total of 232 infusions at a dose of 400 mg/kg every 4 weeks. Adverse effects from such infusions were transient and minimal. Clinically significant abnormalities did not occur. There were no statistically significant differences between the results for IVIgG pH 6.8 and for the new IVIgG pH 4.25 preparation. It was possible to infuse the new IVIgG pH 4.25 reagent at rates of 0.1 ml (5.0 mg)/kg/min without inducing vasomotor adverse effects.

Alterations in the half-life and clearance of IgG during therapy with intravenous gamma-globulin in 16 patients with severe primary humoral immunodeficiency

Published studies of the metabolism of human IgG using trace amounts of radiolabeled IgG demonstrated that the elimination of native IgG followed first-order kinetics but that the half-life of IgG was shortest in patients with the highest serum concentrations of IgG. To evaluate the effect of increasing the serum concentration of IgG on the metabolism of IgG, we determined the half-life and clearance of IgG and tetanus antibody in 16 patients with severe primary humoral immunodeficiency diseases while they received several doses of intravenous gamma-globulin (IVIG). Each patient received 100 mg/kg of IVIG each month and the half-life and clearance of IVIG were determined by following the decline in the serum IgG concentration. The dose of IVIG was adjusted to give a minimum IgG level of 200 mg/dl and the half-life was reevaluated. The dose was again adjusted to give minimum concentrations of 450 mg/dl and two additional studies were performed. Mean doses of IVIG infused increased from 100 to 346 mg/kg. The mean trough serum IgG concentration was 191 mg/dl on the standard dose and increased to 427 mg/dl at the highest dose. The serum half-lives of IgG were highly variable, ranging from 22 to 96 days. The mean decreased from 43 days in the first to 33 days in the third and fourth studies, and the clearances of IgG increased from 1.8339 to 2.4302 mg/kg/day, but the differences were not statistically significant. Patients with the highest serum IgG concentrations tended to have the longest half-lives, suggesting that intrinsic IgG production might falsely prolong the calculated half-life of IgG.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of IgG-associated determinants in reduced and alkylated preparations of human IgG3 by monoclonal antibodies

Using classical typing antisera, previous experiments have failed to demonstrate IgG3 in partially reduced and alkylated preparations of human IgG intended for intravenous application (IGIV). To establish that IgG3 is actually present in such preparations, we designed an enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies as solid-phase reagents and protein A-purified IgG3 as antigen. Three different samples of reduced and alkylated antigen were used: (1) IgG3 isolated from a ready-for-infusion IGIV; (2) IgG3 which was purified from an intramuscular (Cohn fraction II) IgG solution before being subjected to a mild reduction and alkylation procedure, and (3) completely reduced and alkylated IgG3. The reduction and alkylation procedure did not affect the solubility of IgG3, indicating that IGIV prepared in this manner should contain normal quantities of IgG3. In the ELISA, solid-phase monoclonals which were cross-reactive with multiple IgG subclasses clearly reacted with reduced and alkylated IgG3. Furthermore, there was no substantial difference between the quantities of modified and native antigen required for 50% maximal ELISA signal. In contrast, solid-phase monoclonals with IgG3-restricted specificity did not recognize reduced and alkylated material. These results indicate that IGIV prepared by reduction and alkylation has a normal IgG3 content and confirm that some IgG3-specific determinants are altered by the modification procedure.

Comparison of varicella zoster antibody titers in patients given intravenous immune serum globulin or varicella zoster immune globulin

We compared the VZV IgG antibody titers after administration of varicella zoster immune globulin and serum immune globulin intravenously (IGIV) in VZV seronegative pediatric patients with cancer. Four patients received VZIG at standard doses; four received IGIV at 4 ml/kg every 4 weeks for four doses; and five received IGIV at 6 ml/kg every 6 weeks for two to four doses. VZV antibody titers were measured by radiommunoassay (RIA), enzyme-linked immunosorbent assay (ELISA), indirect fluorescent antibody assay (IFA), and neutralizing antibody assay. The mean peak and trough VZV titers by RIA were comparable in all three groups: 1:724 at 4 weeks after VZIG, 1:2048 at 4 weeks after 4 ml/kg IGIV, and 1:776 at 6 weeks after 6 ml/kg IGIV. The titers measured by ELISA, IFA, and neutralizing antibody were comparable after VZIG or IGIV. The VZV titers by RIA were maintained at greater than or equal to 1:1024 after subsequent doses of 4 ml/kg IGIV, and at greater than or equal to 1:256 after subsequent doses of 6 ml/kg IGIV. Adverse effects were rare. The VZV antibody titers assessed 4 to 6 weeks after IGIV administration were equivalent to the titers measured 4 weeks after administration of VZIG.

Prolonged interval high-dose intravenous immunoglobulin in patients with primary immunodeficiency states

Intravenous immunoglobulin can be a very effective form of treatment for patients with primary immunodeficiency states. Recommendations for intravenous dosing previously have been empirically derived. In order to determine the potential prolongation of intervals between infusions following the administration of 500 mg/kg of intravenous immunoglobulin, 11 patients were studied. This high-dose therapy was well tolerated and resulted in a modest prolongation of therapeutic IgG levels when compared with lower-dose 150 mg/kg regimens. Significant variability among individual patients was observed. Implications of this high-dose therapy are discussed.

Intravenous immune globulin therapy in hypogammaglobulinemia. A review

An immune globulin preparation specifically modified for intravenous administration has been employed therapeutically in 30 patients with primary immunodeficiency disease. Our results of this long-term study are summarized within three major categories: (1) Levels of serum IgG produced and maintained after intravenously administered serum immune globulin infusions of 100 to 500 mg/kilo. The disappearance pattern of infused IgG is outlined and individual patient variations emphasized. (2) The therapeutic effects of intravenously administered serum immune globulin therapy are reported and related to dosages of intravenously administered serum immune globulin administered and serum levels of IgG maintained. (3) The incidence and nature of detrimental side effects are outlined, and methods to reduce this problem are indicated. It is recommended that patients with primary immunodeficiency be given from 150 to 200 mg/kilo intravenously administered serum immune globulin, every four weeks, as prophylactic therapy to reduce acute infectious complications. A method to establish an optimum therapy for a specific patient is presented.

Comparative anti-Pseudomonas aeruginosa activity of chemically modified and native immunoglobulin G (human), and potentiation of antibiotic protection against Pseudomonas aeruginosa and group B Streptococcus in vivo

Immunoglobulin G intravenous is prepared by controlled reduction and alkylation of approximately four interheavy chain disulfide bonds per molecule. To determine if the protective activity of antibody modified by this process is diminished, mice were treated with identical doses of reduced and alkylated IgG and native IgG prepared from the same plasma pool. Three hours later mice were given a 10 percent body surface burn followed by challenge with the seven Fisher-Devlin-Gnabasik immunotypes of Pseudomonas aeruginosa. Against five of the seven immunotypes, the 50 percent protective doses were approximately 100 mg or less per kg body weight. Overall there was no significant difference in protection afforded to the mice by the two immunoglobulin preparations indicating that in vivo the activity of IgG against P. aeruginosa remains unimpaired by reduction and alkylation. In the second part of this study, immunoglobulin G intravenous significantly enhanced the activity of tobramycin and carbenicillin in the treatment of P. aeruginosa infection in burned mice and of penicillin G in the treatment of group B Streptococcus 1C infection in normal mice.

Improved response of patients refractory to random-donor platelet transfusions by intravenous gamma globulin

Because of frequent unavailability of HLA-compatible platelets or their inefficiency in increasing platelet counts in patients requiring platelet transfusions, platelet refractoriness remains a major problem. Since human gamma globulin has been shown to interfere with the binding of platelet-reactive immunoglobulin G (IgG) to platelets in vitro, and since gamma globulin has proved effective in reversing destruction of platelets in idiopathic thrombocytopenic purpura, we decided to investigate intravenous gamma globulin as an adjunct to random-donor platelet transfusions. We studied three patients, one with acute T-cell leukemia, and two with aplastic anemia. When a total dose of 2 g/kg of body weight of intravenous gamma globulin was infused over five to six days in these patients, two of them showed a remarkable increment in platelet counts and improved hemostasis with random-donor platelet transfusions. We conclude that intravenous gamma globulin may be used in critical situations to improve the response of patients refractory to random-donor platelet transfusions.

Efficacy and safety of high-dose intravenous immune globulin therapy for antibody deficiency syndromes

Ten patients with antibody deficiency syndromes were admitted to a treatment protocol in which the dose of intravenous immune serum globulin was increased from 100 mg/kg to a maximum of 250 mg/kg each four weeks. The dose increases were determined by recurrence of infection during treatment and by IgG trough levels of less than 400 mg/dl. Infectious episodes during intravenous immune serum globulin treatment responded well to 10 to 20 day long periods of antibiotic treatment, and prolonged infection-free periods were achieved in all patients. Only one hospital admission was necessary during the entire study period. The increase in intravenous immune serum globulin dose to 200 mg/kg did not significantly reduce the recurrence of infections. Infections also occurred in patients whose IgG trough levels were persistently above 400 mg/dl. High doses of intravenous immune serum globulin were well tolerated, and all patients are still receiving intravenous immune serum globulin treatment. A generalized pruritic rash was observed in two patients. In no patient have clinical or laboratory signs of deficiency in cell-mediated immunity developed.