Induction of immunological tolerance in rats to Nippostrongylus brasiliensis infection

A successful attempt was made to induce immunological tolerance to N. brasiliensis in laboratory rats by exposing them to larval infections before the age of immunological maturity.

The adult capacity of rats to eliminate a primary infection in 3 weeks and to acquire resistance to reinfection was developed by 5 weeks of age. On the other hand, primary infections of 250–660 larvae, originating before 4 weeks of age, survived in 61 of 83 rats up to 10 weeks. These rats were not resistant to challenge at 5 or 7 weeks of age, nor did the challenge infection undergo immune elimination. Such tolerance was evident even in rats whose primary worm burden was chemically abbreviated prior to challenge.

It was not always possible to distinguish between tolerant and immune animals on the basis of egg output patterns. Suppression of egg output occurred even in tolerant rats harbouring relatively stable female populations.

For immunological experiments on N. brasiliensis infection in rats, the determination of a ‘take ratio’ is advocated: (20 day take/10 day take) × 100. This ratio eliminates the error inherent in variability of takes and renders comparable the results of different experiments.

The work was carried out in 1965 during tenure by one of us (T.K.) of an Exchange Scholarship under the British–Hungarian Cultural Agreement. Supervision by Professor W. Mulligan and the co-operation of colleagues in the Wellcome Laboratories are gratefully acknowledged.

Cyanogen bromide cleavage and partial sequence of the heavy chain of a pathological immunoglobulin G

The heavy chain of a pathological immunoglobulin G (Daw) of type L, subclass gamma(2b) (We) and Gm(a+)(f-), has been cleaved with cyanogen bromide. The five fragments resulting from the cleavage have been isolated and analysed. The papain-digest fragments, Fab and Fc, have also been cleaved with cyanogen bromide and the products analysed and compared with those from the heavy chain. The order of the five fragments in the heavy chain has been established and the location of some of the inter-chain and inter-fragment disulphide bonds has been determined. The sequence of the N-terminal fragment consisting of 34 residues is reported.

The influence of antibodies on immunologic responses. I. The effect on the response to particulate antigen in the rabbit

The influence of antibody on antibody formation to particulate antigen was examined in the rabbit with special reference to the importance of immunoglobulin type, the amount and relative proportion of antigen and antibody involved, and the specificity of this influence. 19S as well as 7S antibody was shown to be an effective inhibitor of antibody formation, although there was some evidence that 7S antibody was the more efficient of the two in doing so. The inhibitory effect of antibody was found to be specific for homologous antigenic determinants. Both 19S and 7S antibody were also able to enhance antibody formation. In contrast to the suppressive phenomenon, however, enhancement appeared to be nonspecific since antibody reactive with homologous (sheep red blood cell) determinants could enhance the response not only to homologous determinants but to heterologous (dinitrobenzene) determinants conjugated to the red blood cells as well. Smaller amounts of antibody were needed to enhance than to suppress antibody formation, and suppression and enhancement depended to some extent on the amount of antigen as well as to the amount of antibody used. The enhancing and suppressing influence of antibody on antibody formation appeared to be exerted concomitantly, for the response to some antigenic determinants was sometimes suppressed at the same time that the response to others was enhanced. It is suggested that enhancement or suppression of immunologic responses by antibody represents a different balance of at least two competing factors operating together: specific neutralization of appropriate determinants thus decreasing the total effective concentration of these determinants available to stimulate the formation of antibodies, and a nonspecific increase in the availability of antigen to immunologically competent cells.

Phylogeny of immunoglobulin structure and function. I. Immunoglobulins of the lemon shark

Lemon sharks immunized with bovine serum albumin produced two molecular forms of antibodies detectable by passive hemagglutination of antigen-coated, tanned sheep erythrocytes. Throughout the course of immunization 2-ME-sensitive antibody was associated with a 19S immunoglobulin fraction (4-5 mg/ml serum) while late in the course of immunization antibody was found also associated with a 7S immunoglobulin fraction (7-8 mg/ml serum). No evidence for any anamnestic response was found in these animals. Naturally occurring hemagglutinins for sheep erythrocytes were found to be 2-ME-sensitive and present in the 19S immunoglobulin fraction. These immunoglobulin fractions were readily purified by DEAE-cellulose chromatography and Sephadex G-200 gel filtration. Both immunoglobulin molecules yielded equimolar amounts of H and L polypeptide chains when subjected to extensive reduction and alkylation followed by gel filtration in 5 M guanidine-HCl. Antigenically reactive H and L chains were obtained by partial reduction and alkylation followed by gel filtration in 1 M propionic acid. The 7S and 19S immunoglobulin H chains were indistinguishable by fingerprints of tryptic digests, disc electrophoretic patterns, antigenic properties, and mass (molecular weight approximately 70,000), thus suggesting these two molecules to belong to the same immunoglobulin class. The shark 19S and 7S immunoglobulin L chains were indistinguishable from each other by similar criteria and were different from the H chains. These L chains exhibited the electrophoretic heterogeneity of their mammalian counterparts. The 7S (shark immunoglobulin) molecule was shown to have a molecular weight of approximately 160,000 and to consist of 2H and 2L polypeptide chains (total mass congruent with180,000). The 19S molecule was shown to have a molecular weight of 800,000-900,000; therefore, there were probably five 7S subunits per 19S molecule, comparable to mammalian gammaM. Other reasons for considering the 7S and the 19S lemon shark molecules to belong to a class of immunoglobulins comparable to the gammaM class of mammals are that they both have high carbohydrate contents, and H chains of mass similar to micro chains. The lemon shark serum proteins with electrophoretic mobilities comparable to gamma G of mammals were not related to the immunoglobulins of this species. These proteins had no antibody activity and had no antigenic or chemical similarity to either the H chains, the L chains, or the intact immunoglobulin molecules from the lemon shark.

Reaginic antibodies and immunity to Nippostrongylus brasiliensis in the rat. I. The effect of thymectomy, neonatal infections and splenectomy

Rats thymectomized at birth were infected with Nippostrongylus brasiliensis at 6 weeks of age. In some, but not all, rats egg production was greatly prolonged after the primary infection. Thymectomized rats were less resistant than controls to second infections.

In rats infected at birth the development of resistance was significantly delayed. Neonatally infected rats, when they were 6 weeks old, were less resistant to reinfection than adult controls. Rats infected three times in the neonatal period were more resistant to challenge at 6 weeks of age than rats infected once at birth, but less resistant than adult controls. The degree of immunity induced by a single neonatal infection was variable; some rats showed little or no resistance to reinfection 6 weeks later.

Antibody formation, measured by the occurrence of reagins, was altered in the same way by both neonatal thymectomy and neonatal infection. In the thymectomized (immunologically deficient) and newborn (immunologically immature) rats, reagin formation following initial infection was delayed; there was a reduced anamnestic response after challenge; mean titres were lower and more variable than in control animals; and in some rats circulating reagins were never detected.

In thymectomized rats the capacity to demonstrate anaphylaxis was as variable as in control rats, but in the few thymectomized rats in which egg production was prolonged, anaphylaxis was slight at a time when most intact rats had developed the capacity to show anaphylaxis. Rats infected at birth and adult rats infected at the same time were equally susceptible to systemic anaphylaxis 6 weeks later, although by this time there was a marked difference in the degree of resistance to the parasite developed by the two groups.

In adult rats splenectomy before, during or after initial infection had no effect either on the rate of development, or the degree of immunity induced by primary or secondary infections, or on antibody formation.

We would like to thank Miss W. Griffiths and A. J. Edwards for their willing technical assistance. This work was done whilst one of us (B.M.O.) was the holder of a Wellcome Fellowship of the Animal Health Trust.

Changes in the protein content of the serum and intestinal mucus of sheep with reference to the histology of the gut and immunological response to Oesophagostomum columbianum infections

Sheep infected with Oesophagostomum columbianum showed anorexia, loss of weight, diarrhoea and macroscopically obvious oedema and inflammation of the alimentary tract. Arthus-like lesions caused by the larvae developed particularly in the large intestine.

The gross immunological responses of the sheep were associated with antibodies in greater titre within the mucus of the gut than in the serum. Acquired immunity was manifest through an antibody-antigen reaction which was localized mostly in the large intestine and which involved proliferation of the lymphoid tissue of the gut and an increased synthesis of protein. Lower titres of antibody in serum than in mucus may indicate leakage of antibody away from the gut. The direct effects of antibody were established by the respiratory inhibition of the 3rd-stage larvae. The presence of antibody was associated with particularly high concentrations of β globulin after first and β and γ globulins after second infection. Specific antibody was demonstrated in these protein fractions by blockage of electrophoretic movement by larval antigen in the buffer.

The antibody-antigen reaction may act as a trigger which releases the nonspecific effects of excess mucus production and oedema which causes mechanical dislodgement of the infection. The natural and specific respiratory inhibitory effects of mucus on the worm would facilitate this dislodgement process.

The greatest cellular reactions occurred where there was an active infection. Usually these reactions were associated with oedema, hyperaemia and an increase in the size of the mesenteric lymph nodes.

The genetic control of gamma-globulin heavy chains. Studies of the major heavy chain subgroup utilizing multiple genetic markers

The genetic control of gammaG1-heavy chains was investigated by taking advantage of two recently described genetic antigens, Gm(z) and Gm(y), both produced by heteroimmunization of rabbits with myeloma proteins. These were studied in conjunction with known genetic markers, Gm(a) and Gm(f). The results indicated that among Caucasians there are two major allelic genes, Gm(za) and Gm(fy), coding for distinct varieties of gammaG1-heavy chains. Each of these contains a pair of genetic antigens which are located on different fragments of the chain and can be separated by enzymatic splitting with papain. The different areas of the heavy chains appear to be under the control of the same gene. In Mongoloid populations a grouping of three genetic antigens, Gm(f), (y), and (a), was found on isolated myeloma proteins and normal gamma-globulins indicating the presence of a Gm(fya) gene. The possible genetic events leading to the contrasting Caucasian and Mongoloid genes are discussed. In the gamma-globulin system the occurrence of multiple genetic antigens in different positions of the same heavy chains is the general rule. A better understanding of the relationships between the genes for the gammaG1-subgroup to those for the gammaG2- and gammaG3-subgroup has been obtained through the use of the multiple genetic markers. Strong evidence was obtained for intergenic crossover mechanisms to explain racial differences in the relationships of these genes as well as certain unusual gene complexes found through family studies. Further evidence was obtained for mapping the closely linked genes for the three subgroups in a specific order.

Light and heavy chain components of gamma globulins in urines of normal persons and patients with agammaglobulinemia

A heavy chain component of gammaG-globulins in normal urines has the characteristics of the proteolytic digestion product, Fc-fragment. This fragment is estimated to compose up to 15% of the gamma globulins present in urines. In contrast to urinary light chains, the urinary Fc-like fragment probably represents a catabolic component in normal gammaG-globulin metabolism. The light chains of the urine constitute more than half the total gamma globulin present. The calculated kappa/lambda ratio of light chains averaged 1.9 in ten urines, but the ratio in individual urines varied widely to either side of this figure. In two adult patients with agammaglobulinemia whose sera contained less than one-hundredth the normal gamma globulin levels, the urinary Fc-like fragment was absent, whereas the light chain levels were only one-tenth the average normal level. Treatment with exogenous gamma globulins resulted in normal or near normal Fc-like fragment excretion, whereas light chain excretion was only modestly affected.

Fractionation on DEAE-Sephadeex of normal and a-myeloma human sera. I. Electrophoretic heterogeneity of gamma-a globulins

DEAE-Sephadex chromatography was employed to fractionate the γA globulins of normal and A-myeloma human sera. By immunoelectrophoresis, the normal γA globulins had mobilities ranging from that of γ1 to α2 globulins, whereas the myeloma γA globulins were of essentially uniform mobility. Most of the normal γA globulins were homogeneous with respect to sedimentation in a sucrose density gradient, indicating that their immunoelectrophoretic heterogeneity was due largely to differences in molecular charge rather than size.