Isotype concentrations of human antibodies to Haemophilus influenzae type b polysaccharide (Hib) in young adults immunized with the polysaccharide as such or conjugated to a protein (diphtheria toxoid)

Antibody responses of young adults to Haemophilus influenzae type b polysaccharide (Hib) or its protein conjugate were studied with special attention to the isotype composition of the antibodies. Three conclusions of interest can be made: 1) Immunoglobulin G (IgG) antibodies in polysaccharide-immunized volunteers displayed the subclass pattern previously found in antibodies to meningococcal type A polysaccharide. IgG1 was the predominant subclass in IgG antibodies of some individuals, IgG2 in others. Still others had the two subclasses in varying but more even proportions. 2) The conjugate vaccine induced a geometric mean response 2 to 3 times higher and an IgG response 4 times higher to Hib than the polysaccharide vaccine. 3) Anti-Hib antibodies induced by the conjugate vaccine still had essentially the same IgG subclass composition as anti-Hib antibodies induced by the polysaccharide. This composition was strikingly different from the composition of the anti-diphtheria toxoid response induced by the same conjugate vaccine.

Isotypes of antibodies induced by plain dextran or a dextran-protein conjugate

Mice were immunized with alpha (1----6) dextran or its protein conjugate with monthly intervals, and their antibodies were quantitated with an isotype-resolved radioimmunoassay. Plain dextran (molecular weight = 5-40 million) induced antibody concentrations varying from 20 to 80 micrograms/ml (primary response). The response to a booster injection was weaker than the response to the first injection. More than 90% of anti-dextran antibodies were IgM but IgG and IgA responses could be unequivocally demonstrated. IgG1 and IgG3 were the predominant subclasses of IgG. Dextran antibody responses to a conjugate of dextran (molecular weight approximately equal to 10000) and chicken serum albumin (CSA) were stronger (80-300 micrograms/ml) than responses to plain dextran, and anti-CSA responses to the conjugate were even stronger (up to 900 micrograms/ml). Three distinctly different isotype patterns were observed. A pattern IgM much greater than IgG1 = IgG3 greater than IgG2a prevailed in responses to the plain dextran and in primary anti-dextran responses to dextran-CSA. Another pattern IgG1 greater than IgG3 greater than IgM greater than IgG2a was observed in late anti-dextran responses to dextran-CSA. The third pattern IgG1 much greater than IgG2a greater than IgG3 approximately equal to IgM was characteristic of anti-CSA antibodies. Little IgG2b or IgA antibodies were found. Different isotype patterns can best be explained on the basis of secondary factors such as T cell help.

Triggering infections in reactive arthritis

Certain microbes like yersinia, salmonella, shigella, campylobacter, chlamydia, and possibly gonococcus can trigger reactive arthritis especially in patients of the HLA-B27 type. In the present study we have used serological and culture methods to identify the probable triggering infection in 50 consecutive HLA-B27 positive patients diagnosed as having reactive arthritis. The two most common triggering agents thus identified were Yersinia enterocolitica (12 patients) and Chlamydia trachomatis (11 patients). In addition six patients had high antistreptolysin O titres and two high teichoic acid antibody titres suggesting group A streptococci and Staphylococcus aureus as triggering agents. In 13 patients no preceding infection could be identified. The identity of the infective agent seems to have very little effect on the clinical picture of the reactive arthritis - the only difference between the various aetiological groups in the present material was absence of fever in the patients with a preceding C. trachomatis infection, of whom only one out of 11 had a temperature greater than or equal to 38 degrees C, whereas 13 of 16 patients with a preceding enterobacterial, and five of the eight patients with a streptococcal or staphylococcal infection had raised temperatures.

Immunoglobulin G subclass antibody responses in influenza A and parainfluenza type 1 virus infections

Antibody responses in immunoglobulin G1, G2, G3, G4, A (IgA1) and M isotypes were studied in 10 patients with an acute influenza A and in another 10 patients with a parainfluenza type 1 virus infection using radioimmunoassay with standardized monoclonal anti-immunoglobulins. A four-fold or greater increase of antibody in patients have an acute influenza A virus infection, were found in IgG1 (all 10 cases), IgG3 (seven cases), IgG4 (eight cases) and in IgA1 (six cases) whereas IgG2 and IgM responses were observed only in one and three cases, respectively. The antibody titre values were converted to immunoglobulin units by multiplying the titre by a pre-determined correction coefficient compensating for the varying affinity of the individual monoclonal anti-immunoglobulins. These units were then used to calculate the actual proportions of each isotype. In the convalescent phase, 78% of total anti-influenza A antibodies were estimated to be of IgG1 isotype and other immunoglobulin isotypes varied from 3 to 7% of total. Similar results in parainfluenza virus antibodies were obtained with serum pairs from patients with an acute parainfluenza virus infection.

Immunogenic properties of alpha (1----6) dextran, its protein conjugates, and conjugates of its breakdown products in mice

Mice were immunized with alpha (1-6) dextran, either as such or coupled to protein carriers, and their anti-dextran response was measured by a solid-phase radioimmunoassay and the Farr assay. Like earlier investigators we found that protein-conjugated dextran was more antigenic than plain dextran. Our novel findings were that (1) a standard dose (30 micrograms of dextran per injection) coupled to strongly antigenic protein (chicken serum albumin (CSA) was three times more antigenic than dextran coupled to weakly antigenic bovine serum albumin (BSA); (2) dextrans of low molecular weight (1000-10,000 daltons) coupled to CSA induced at least ten times stronger secondary responses than did a similarly coupled macromolecular dextran (5-40 million daltons); (3) variation of the CHO/protein ratio from 0.3 to 1 had little effect on the antigenicity of the dextran. Increase of the ratio from one appeared to decrease immunogenicity when BSA was the carrier but not when CSA was the carrier.

C3c and C3d fragments of human C3 bind myeloma IgG1 and IgG3 proteins

Eight human myeloma proteins, two of each IgG subclass, were studied for binding to solid-phase C3c and C3d by the ELISA technique. Myeloma IgG1 kappa, IgG1 lambda, IgG3 kappa and IgG3 lambda proteins bound to C3c and C3d, while two IgG2 kappa, and two IgG4 kappa proteins failed to show significant binding affinity. The results suggest that like C1q, the stable binding sites of C3, located on the C3c and C3d parts of the molecule, have affinity for IgG subclasses 1 and 3.

The four subclasses of IgG can be isolated from mouse serum by using Protein A-Sepharose

We confirmed the findings of Ey and colleagues that mouse IgG is absorbed by protein A-Sepharose at pH 8.0. Also confirmed was their finding that IgG1 mainly elutes from such a column by means of a buffer with pH 6.0 and that the corresponding pH values for IgG2a and IgG2b were 4.5 and 3.5. We made the new finding that the bulk of IgG2a bearing allotypes a or j eluted already at pH 5, in contrast to IgG2a bearing allotype b. Another new finding was that IgG3 was mainly eluted at pH 4.5 regardless of the allotype. All four subclasses of IgG could thus be physically separated if the allotype was a or j (the only known exception is allotype b). Separation of IgG2a and IgG3 was achieved even when the allotype was b by using a pH gradient for elution. IgG2a came out at a slightly higher pH than IgG3. Mouse IgG antibodies against group A streptococcal polysaccharide belonged mostly to IgG3 and, to a lesser extent, to IgG2a and IgG2b.

Immunological methods based on antigen-coupled bacteriophages

Simple chemicals, many proteins, nucleic acids or polysaccharides can be coupled to bacteriophages without completely destroying their infectivity. The coupled phages are then sensitive to inactivation by the relevant antibodies. Thus it is possible to construct phage inactivation assays for antibodies or inactivation inhibition assays for antigens. The advantages of the bacteriophage methods include superior sensitivity and good stability of the reagents. The phage inactivation method detects preferably high-affinity antibodies, but what really matters is a high avidity. Because of the polyvalency IgM antibodies can have a high avidity associated with moderate affinity, and therefore low amounts of IgM class antibody, for instance natural antibody, are often measurable by this test. The chemical conjugation inactivates a proportion of the bacteriophages. If the antigen can be made chemically reactive (self-coupling), approximately 10% of the phage particles escape this inactivation and can serve as indicators of antibody action. When the antigen cannot be made chemically reactive, this inactivation is more complete and the phage assay is less satisfactory.

Establishment of a human lymphoblastoid cell line with specific antibody production against group A streptococcal carbohydrate

A human lymphoblastoid cell line, secreting specific antibody against Group A carbohydrate (A-CHO) was established by pre-selection of antigen binding normal human lymphocytes, followed by Epsetin Barr virus (EBV) induced immortalization. Culture supernatants were assayed for anti A-CHO antibodies by radioimmunoassay, N-acetyl-glucosamine-coupled T4-phage plaque inhibition tests and passive hemagglutination. As a rule, the supernatants contained about 10 micrograms/ml anti-A-CHO antibodies of the IgM-kappa type. The antibody was fractionated and partially purified on an N-acetyl glucosamine Sepharose 4B column with a recovery of about 3 micrograms/ml of supernatant.

The role of B-cell memory in secondary IgG and IgM responses

Mice were primed with the hapten 3-nitro-4-hydroxy-5 iodophenacetic acid (NIP) conjugated to chicken globulin (cg) and were boosted 2, 6, or 12 months later with CG conjugates of the related haptens 3,5-diiodo-4-hydroxyphenacetic acid (DIP) or 3-nitro-4-hydroxphenacetic acid (NP). Accelerated secondary responses were demonstrated both in the 7S and 19S class. Fine-specificities of secondary-response antibodies were studied by the hapten inhibition method of haptenated bacteriophage inactivation. 7S antibodies were found to have the fine-specificity of anti-NIP antibodies regardless of whether DIP or NP was the booster hapten ('original antigenic sin'). 19S antibodies had the fine-specificity of anti-DIP when DIP was the booster hapten. NP as the booster hapten resulted in 19S antibodies whose fine-specificity was intermediate between anti-NIP and anti-NP. A strong B-cell memory could thus be demonstrated in the 7S antibody response and a weak B-cell memory in the 19S antibody response.