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It has previously been shown that rats do not expel a primary infection of Nippostronglus brasiliensis during lactation. In the present paper, three aspects of the immune response of the lactating rat to the parasite were examined and compared with the response of non-lactating rats. Protective and reaginic antibodies were present in the circulation of rats first infected during lactation, in titres as high or higher than those in non-lactating controls. The intestinal mast cell response was similar both in timing and magnitude and lactating rats became susceptible to shock with the i.v. injection of antigen. Attention was drawn to the similarity between the response of the lactating rat and that of the neonate to this infection. [ABSTRACT FROM AUTHOR]

Red cells sensitized with naturally occurring or 'immune' fowl antibody were lysed by fresh fowl serum. This fowl complement could not be replaced by that of human, rabbit or guinea pig. Both naturally occurring and 'immune' antibodies to red cells in the mammalian species tested did not lyse with fowl complement. Lysis by fresh fowl serum of sheep red cells sensitized with mammalian antibody is due to the presence of naturally occurrent antibody to these cells in the fowl serum; the enhancement of this lysis by the mammalian antibody will be described more fully in the next paper. Naturally occurring antibody to sheep red cells present in turkey serum and 'immune' antibody to fowl red cells were not lytic with fresh turkey serum, with fowl complement, with guinea-pig complement or with any combination of these. Some properties of fowl complement are given. [ABSTRACT FROM AUTHOR]

Rabbits made immunologically unresponsive by neonatal administration of HSA, HGG or BSA were given a course of intravenous injections of the respective antigens, adsorbed on alum, after a lapse of 13-27 months since the last administration of antigen. 8/12 responded to HSA, 4/5 to HGG, 9/10 to BSA, as judged by immune elimination of antigen, but this was delayed in onset and slow compared with that in previously untreated rabbits. The antibody formed was small in quantity and usually failed to precipitate with antigen. The sedimentation coefficients of 131I-labelled antigens, in the presence of excess antibody, were measured by ultracentrifugation through a sucrose density gradient. These showed that only small complexes were formed in some of the non-precipitating antisera. In one instance the diffusion coefficient of the complex was also measured, by a technique based on diffusion through agar gel. The calculated molecular weight of the complex, 330,000 indicated the presence of only two combining sites on the antigen. Combination of the anti-HSA sera with an HSA fragment was also measured. Whereas the amount of the fragment bound by ordinary hyperimmune anti-HSA sera was about one-fifth the HSA bound, the amounts bound by the test sera were relatively much less. Some non-precipitating sera failed to bind the fragment, although they bound HSA. These findings indicate that following neonatally induced immunological unresponsiveness the capacity to respond to antigen returns piecemeal in respect of different parts of the antigenic mosaic, and that it may be severely restricted. The theoretical implications are discussed. [ABSTRACT FROM AUTHOR]

The immunological responses of rabbits to HSA, HGG or BSA were tested at various times later in animals which had received the corresponding antigens before or shortly after birth. As judged by the criterion of failure to show immune elimination of antigen, a high proportion of the rabbits remained unresponsive at times when it was calculated that all the originally administered antigen would have been eliminated from the circulation. Furthermore, removal of antigen by passively administered antibody failed to restore the capacity to respond. It is concluded that, in respect of the antigens used, their persistence in the extracellular body fluids is not a prerequisite for maintenance of immunological unresponsiveness.
Further administration of the same antigen to rabbits which had escaped from a state of specific immunological unresponsiveness generally produced a very weak response, and in a few instances resulted in a return to the unresponsive state.
When the cross-reacting antigens HSA and BSA were administered adsorbed on alum to rabbits made unresponsive by neonatal contact with BSA and HSA respectively, and at the same time a further dose of the original antigen was given, antibodies were formed which were specific for the second antigen and did not cross-react with the first. In only 1/9 animals was responsiveness to the first antigen restored. The significance of these results is discussed. [ABSTRACT FROM AUTHOR]

Cold agglutinins were separated from the sera of eleven patients suffering from the cold-antibody type of acquired haemolytic anaemia by the dissociation of the specific antigen-antibody complexes. The electrophoretic mobility of the cold antibody was found to correspond to that of γl globulin in each case. Ultracentrifugal studies carried out on eluted cold antibodies prepared from the sera of seven patients demonstrated that the antibodies were macromolecules (S20,w∼18.1). In one instance the sedimentation coefficient of the cold antibody was demonstrated to be similar to that of electrophoretically separated ‘γ1 globulin’ prepared from the same serum, indicating their identical physical state. The results of treating the sera of nineteen patients with the cold-antibody type of acquired haemolytic anaemia with mercapto-ethanol further confirmed that the cold antibodies were all macromolecules, whether derived from idiopathic cases or cases secondary to some other known disorder. [ABSTRACT FROM AUTHOR]

Cold antibodies were separated from the sera of six patients suffering from the cold-haemagglutinin syndrome and from one patient with acquired haemolytic anaemia secondayr to lymphosarcoma by dissociation of the specific antigen-antibody complexes. The eluted antibodies were studied (a) by immuno-electrophoresis along with the parent sera against horse anti-human serum and (b) by double diffusion in agar gel along with electrophoretically separated ‘γ1 globulin’† against anti-19S ‘γ-globulin’ rabbit sera. The protein forming the cold antibody was localized in the β2-M position on immuno-electrophoresis in each instance. It was found by double diffusion in agar gel to be immunologically identical with the protein forming the abnormal ‘γl-globulin’ electrophoretic peak in the parent serum. The results of these experiments indicate that the cold antibodies derived from patients with the cold-antibody type of acquired haemolytic anaemia are macro-molecular globulins. [ABSTRACT FROM AUTHOR]

A critical review is given of Goldberg's (1952, 1953) theory of Antigen-Antibody reactions in vitro. Goldberg's assumptions and the mathematical development of his theory are described in detail. Comparisons of Goldberg's predictions with experimental results are given in graphical form. Some criticisms are made of Goldberg's use of equations in regions in which the derivations given by him are not valid. [ABSTRACT FROM AUTHOR]

The effect of an horse anti-mouse thymocyte globulin (ALG) preparation on the primary and secondary immune responses to sheep erythrocytes (RBC) was studied in 2-3-month-old male A/HeJ, C57B1, BALB/c, DBA/1, CBA and C3H mice. A wide variation in the primary and secondary responses of the individual strains was noticed but in ail cases these were significantly suppressed by ALG pretreatment. The capacity of the ALG to suppress the primary immune response was not overcome by increasing the antigen dose from 3 × 107 to 3 × 109 sheep RBC. [ABSTRACT FROM AUTHOR]

Irradiated (NZB × BALB/c)F1 mice were injected with syngeneic bone marrow cells, syngeneic or parental thymus cells, and sheep red cells. The antibody plaque-forming cell response depended on the number of sheep cells and the age and strain of the thymus cells. Young or adult BALB/c thymus, and young hybrid thymus, responded best to low numbers of sheep cells; with higher numbers they became tolerant. Adult hybrid thymus, and young or adult NZB thymus, responded better to high numbers of sheep cells. Hybrid mice irradiated and restored with BALB/c bone marrow developed thymus cells with the reactivity of BALB/c thymus. It is argued that NZB mice, and older hybrids, may develop autoimmunity because of an abnormality of tolerance induction manifested in their thymus cells, but of bone marrow origin. [ABSTRACT FROM AUTHOR]

A complete evaluation of the immunogenicity of oligo-L-lysines and their mono-ε-DNP derivatives requires a determination of their capacity to prepare animals for secondary responses to a highly immunogenic analogue and to elicit secondary responses in animals prepared with such an analogue. It is shown here that 1-ε-DNP-tetra-L-lysine is not effective, or only marginally effective, in preparing PLL+ guinea-pigs for secondary anti-DNP responses to DNP-poly-L-lysine whereas 1-ε-DNP-nona-L-lysine is active in such preparation. Similarly, in animals primed to DNP-ovalbumin, supplemental immunization with tetra-L-lysine is not effective in preparing strain 2 guinea-pigs for a secondary anti-DNP response to DNP-poly-L-lysine whereas both nona-L-lysine and poly-L-lysine are effective, the latter to a considerably greater degree. In animals primed with DNP-poly-Llysine or with DNP-ovalbumin and poly-L-lysine, DNP-poly-L-lysine elicits secondary anti-DNP responses whereas neither 1-ε-DNP-nona-L-lysine or 1-εDNP-tetra-L-lysine do. The data indicate that a hierarchy in the degree of immunogenicity exists within the lysyl peptides series with poly-L-lysine more immunogenic than nona-L-lysine and this, in turn, more immunogenic than tetra-L-lysine which is either nonimmunogenic or marginally immunogenic. Further, the determination of immunogenicity is a feature either of the 'helper' cell population or of a step in the response which is prior to the activation of 'helper' cells. [ABSTRACT FROM AUTHOR]

The onset of the exponential expulsion of Nippostrongylus brasiliensis worms in the rat is associated with a sharp burst of intestinal mast cell activity and increased permeability of the bowel wall. It was found that the onset of maximum velocity of worm expulsion occurred earlier in female rats than in male rats and proceeded at a faster rate. There was a corresponding difference in the timing of the mast cell rise and macromolecular leak between the sexes. This suggested that there is a relationship between these events. Cortisone, a drug known to stop worm expulsion and to suppress the mast cell response, also prevented the macromolecular leak. Electron microscopy showed that during the period of increased permeability a pathway for protein tracers had opened up between the epithelial cells and it is suggested that this is the route for enhanced antibody transfer across mucous membranes. We suggest that a stimulus or stimuli from the parasite cause synchronous development of new populations of mast cells, IgE-producing plasma cells and plasma cells synthesizing antibodies of other classes possessing an anti-worm effect. It is also suggested that these mast cells discharge their pharmacological mediators by an allergen-reaginic antibody mediated system and that these mediators create a pathway through the intestinal mucosa for the translocation of antibody. [ABSTRACT FROM AUTHOR]

The enhancement effect of some antigens on in vitro colony formation by normal mouse bone marrow cells is mediated through a normal serum αmacroglobulin (αM) which is present in newborn animals and shows no immunological specificity. The proportion of antigen and αM affects colony enhancement, and it has also been shown that specific antibody successfully competes with αM for the antigen. It seems likely that antigen-αM complex acts directly on the colony forming cell, rather than indirectly through release of colony stimulating factor. The possible relevance of this phenomenon to immune induction and, to the effect of antigens in promoting irradiation survival is discussed. [ABSTRACT FROM AUTHOR]

The immunological response of the primitive mammal Tachyglossus aculeatus has been studied. We have shown that this animal responds to flagella from Salmonella adelaide with production of mercaptoethanol-resistant antibodies during both primary and secondary responses. Although an anamnestic secondary response could be demonstrated, it was of much smaller magnitude than that of phylogenetically higher placental mammals. Serological investigations demon- strated the presence of a mercaptoethanol-sensitive antibody of high molecular weight and an antibody of lower molecular weight which was mercaptoethanol resistant. These two antibodies seem to be analogous to IgM and IgG antibodies of higher mammals. [ABSTRACT FROM AUTHOR]

The interaction between 7S IgG2 from unimmunized guinea-pigs and macrophage-rich peritoneal exudate cells from oil-stimulated guinea-pigs was examined by 125I-labelled IgG2 uptake. The cell uptake of 125I-labelled IgG2 reaches a maximum after 90 minutes at 20°; increased levels of labelling (1 to 23 atoms of iodine per immunoglobulin molecule) lead to slightly enhanced uptake, but the effect does not exceed experimental variability. Peripheral white blood cells bind relatively low levels of IgG2; the uptake by peritoneal cells is attributable primarily to a subpopulation of glass-adherent cells, presumably macrophages. Binding of IgG2 to macrophages is reversible even with a mild washing procedure. Repeated washing of cells did not affect the association constant, but the apparent number of receptor sites per cell was progressively reduced. After correction for the washing procedure employed, the number of IgG2 receptor sites was estimated as 2.5 ± 0.4 × 106 per cell; the association constant (Ka) was 1.46 ± 0.45 × 106 L/M at 20°. [ABSTRACT FROM AUTHOR]

Naturally occurring cellular and humoral immunity to a purified polyglycerophosphate (teichoic acid) have been observed in normal albino rats. Skin tests as well as in vitro correlates of delayed hypersensitivity yielded positive results in more than 50 per cent of rats between the ages of 24 and 40 weeks while rats 6-20 weeks old exhibited no cellular responses, Passive haemagglutination assays for natural antibodies to glycerol-teichoic acid revealed their occurrence in all rats between the ages of 6-20 weeks as well as in most of the older rats examined. These antibodies were usually found in the IgM fraction, but some animals possessed them in the IgG-containing fraction. The regular appearance of antibodies before the appearance of cellular response, if confirmed, may imply that B-cell responses precede T-cell responses in certain circumstances. [ABSTRACT FROM AUTHOR]

Long persisting antigenic stimulation at immunogenic levels leads to a profound inhibition of antibody formation. With Brucellus abortus, there is first a brief and high IgM response. IgG antibody titres remain at a low level for some days, and then begin a slow and progressive increase, leading to a rather persistent maximum, and finally after about 300 days, to the state of inhibition. When the same total dose is given with monthly intervals, the effect is quite different, with similar IgM and IgG peaks being observed after each dose. The inhibited animals respond moderately to a ten-fold higher antigen dose, and only with IgG. Six months after interruption of the persistent antigenic stimulus, a strong response can be obtained after a new antigenic stimulation, with a substantial proportion of IgM. It is concluded that persistent antigenic stimulation plays a major role in the change from IgM to IgG synthesis. [ABSTRACT FROM AUTHOR]

The classes of immunoglobulin-containing cells in the lungs of mice after primary infection with Sendai virus were studied using an indirect immunofluorescence technique. It was found that during the first 5 days of the infection there was a considerable increase in all classes of immunoglobulin-containing cells with the IgA-containing cells retaining their pre-infection predominance. By the 6th day of the infection both IgG and IgA cells were present in equal numbers. This 1: 1 ratio persisted for nearly 30 days and was followed by a gradual reversion to IgA excess. IgM-containing cells represented only 1/15-1/30 of all immunoglobulin-containing cells at any time during the infection. [ABSTRACT FROM AUTHOR]

Production of antibody against major trasplantation antigens has been studied in sheep receiving osteoarticular allografts at the knee joint. These investigations have shown that this type of allograft leads to the rapid production of serum antibodies in the recipient animal. It was found that a high proportion of the sheep used in these studies possessed antibodies before operation. A large number of the animals which possessed antibody against major transplantation antigens prior to operation developed a wide spectrum of antibodies after operation more rapidly than did those recipients who had no pre-existing antibody. A smaller number showed an increase in antibody spectrum which was comparable with non-sensitized recipients. An analysis of the patters of antibody production was carried out in order to assess the possible benefits of reducing the bony component of the graft in lowering its immunogenicity. It was found that the thickness of bone carried by the graft was largely irrelevant and the immune response was initiated with only small amounts of bone. There is some evidence in this data that the surface area of bone is important in determining the pattern of the immune response. [ABSTRACT FROM AUTHOR]

Rabbit hyperimmune γ-globulin was produced against type 5 adenovirus. This was digested with pepsin to produce bivalent fragments of antibody. These fragments retained the capacity to precipitate with antigen, but were defective in their power to neutralize virus infectivity. Their neutralizing capacity deviated from that of native antibody in the following ways : The proportion of virus neutralized was smaller. The progressive neutralization of virus ceased within 10–15 minutes of mixing virus and fragments of antibody. The rate of neutralization of virus depended only on the concentration of fragments of antibody, and was independent of the relative proportions of virus and antibody fragments. Over the ranges tested the antibody fragments inactivated an approximately constant proportion of virus irrespective of the amount of virus used in the primary, mixture. There is a brief discussion of the significance of these results for an understanding of the mechanism by which complete antibody neutralizes virus infectivity. [ABSTRACT FROM AUTHOR]

Rats, injected with crude bovine heart extracts, showed dissociation of their immunological response. Complement-fixing and capillary precipitating anti-bodies were produced, active against particulate antigens, while tanned-cell haemagglutinating and gel-diffusing antibodies were active against soluble antigens. Particulate antigens were centrifuged down from tissue extracts as 60,000 g but not at 12,000 g. The kinetics of production and specificity differed in the two groups of antibody. When rats were injected with bovine tissues from birth, to produce immuno-tolerance, they did not produce complement-fixing or capillary precipitating antibodies on later challenge with bovine heart but did produce haemagglutinating and gel-diffusing antibodies. Even before challenge, pretrated rats showed haemagglutinating antibodies, while the response by this test to the further immunization was partially suppressed. [ABSTRACT FROM AUTHOR]

Erythrocytes labelled with chromium51 were injected into embryos and young chicks and a similar challenge given soon after the majority of the initial dose had been eliminated. While tolerance was the typical response in embryos and chicks up to 3 days of age, immunity could be induced in most chicks from this time onwards. The intensity of the immune response increased rapidly until the 12th day of age. No maternal antibody could be detected. Pretreatment of the embryo with testosterone impaired the immune response of 14-day-old chicks. [ABSTRACT FROM AUTHOR]

Rabbits previously immunized to two antigens were restimulated by the injections of one antigen followed, 1 day later, by the second. Spleens were removed 2 days after the injection of the second antigen and a cell suspension prepared. Such preparations synthesized antibody to both antigens simultaneously when incubated in vitro. The system-synthesizing antibody to the first antigen, however, was 1 day in advance of the other, developmentally. The effect of various metabolic inhibition on cell survival and the incorporation of radioactive amino acid into each antibody and into cell-proteins was measured. By comparing the effect of each inhibitor on these four parameters it was found that the inhibition of antibody synthesis by ethidium bromide, mitomycin C, 6-mercaptopurine, 5,6-dichlorobenzimidazole riboside, 6-thioguanosine and X-irradiation was secondary to a general derangement of cell metabolism. In contrast, the thymidine analogues, 6-azauridine and possibly colchicine exerted a more selective effect on the antibody formation mechanism. The thymidine analogues and 6-azauridine did not appear to inhibit antibody synthesis per se, but to prevent the development of antibody-forming capacity. The significance of these results is discussed. [ABSTRACT FROM AUTHOR]

Thirteen out of fourteen normal mature rabbits injected with sulphanilazo-human-serum-albumin produced antibodies against sulphanilic acid. In contrast, out of fifteen mature rabbits which had received human serum albumin at birth, none produced detectable antibodies to sulphanilic acid after injections of the sulphanilazo-human-serum-albumin. Fourteen out of fifteen normal mature rabbits produced antibodies to sulphanilic acid after injections of sulphanilazo-rabbit-serum-albumin. One out of nine mature rabbits which had been injected neonatally with sulphanilic acid produced antibodies against the hapten when immunized with the sulphanilazo-human-serum-albumin. The implications of these results are discussed in relation to some current views on antibody formation. [ABSTRACT FROM AUTHOR]

The response to primary antigenic stimulation was measured in C3H mice bearing two types of plasma-cell tumours, the 5563 tumour producing γ-type myeloma proteins and the 5674 tumour producing β-type myeloma proteins. Haemocyanin and pneumococcus type III polysaccharide, which produce 6.5S antibodies, and sheep erythrocytes, which produce 18S haemolysins, were used. Levels of serum antibody to all antigens were low in mice with the plasma-cell tumours, compared with those in normal mice, or mice with a mammary carcinoma. The larger the tumour, the lower were the antibody levels. Antibody levels were lower generally with the 5563 tumours than with the 5647 plasma-cell tumours of similar weight. Although rapid catabolism of normal gamma globulins contributes to the low level of serum antibody in mice with the 5563 γ-type tumour, diminished responsiveness of the antigen-susceptible cells appears to be the principal factor in the impaired antibody response in mice with the 5647 β-type plasma-cell tumour. [ABSTRACT FROM AUTHOR]

Examines the autohemolysin-producing cells in the peripheral blood and some tissues of mice following mice injection of bacterial vaccines. Role of micro-organism in the development of autoimmunity; Formation of the anti-tissue antibodies during the immunological response to bacterial products; Preparation of bacterial vaccines from 24-hour Agar cultures of Staphylococcuss aureus strain.

The capacity of CBA mouse B lymphocytes to bind polyvalent rabbit anti-mouse immunoglobulin antibody, even when this reagent is present in low concentration, was used as an index of a lymphocyte's B cell status. Various mouse tissues were held for 30 minutes at 0° with 0·2 μg/ml of 125I-labelled anti-Ig, and smear preparations of washed cells were examined, following radioautography, for their content of B cells. The survey covered two areas of B cell differentiation, namely the spontaneous emergence of B cells in the mouse foetus, and the development of B cells in lethally irradiated mice that had received early foetal liver as a source of haematogenous stem cells. The foetal survey suggested a multifocal origin of B cells, commencing 3 days before birth, in all major sites of erythromyelopoiesis, namely liver, spleen and bone marrow. Lymph nodes showed B cells later than did these organs, and thymus contained virtually no B cells at any stage. A rapid influx of B cells into lymph nodes took place shortly after birth. The CBA mouse is born with somewhat over 105 B lymphocytes in toto, of which the majority are in liver, spleen and blood. The irradiation-recovery study showed: (1) that B cells are, statistically, more sensitive to high dose irradiation than T cells; (2) that a B cell-free stem cell source can repopulate the B cell pool; (3) that repopulation is surprisingly slow; and (4) that numerical and functional recovery of B cells parallel each other to a reasonable degree. The significance of the results is discussed from the viewpoints of lymphocyte differentiation and immunological tolerance. [ABSTRACT FROM AUTHOR]

Cell kinetics of the 2,4,6-trinitrophenyl (TNP)-erythrocyte response in non-immune, immune, and vinblastine-treated immune BDF1 mice were studied by measuring hapten- and carrier-RFC and hapten- and carrier-PFC responses at various time intervals. Injection of a single dose of horse red blood cells alone enhances the anti-TNP response. [ABSTRACT FROM AUTHOR]

A system for studying in vitro the antibody response against a single determinant and to ail the determinants of a macromolecule (β-D-Galactosidase of Escherichia coli) is described. It consists of culturing fragments of rabbit lymph nodes (either preimmunized in vivo or not) and exposing them to antigen in vitro. Antibodies secreted into the culture during several days, and up to 3 months in the secondary response, were titrated for: (a) one-hit activation of AMEF, the cross-reacting :material produced by a point mutant Lac- E. coli; and (b) precipitation of wild type enzyme. Titrations of activating and binding antibodies are very sensitive owing to the amplification potential inherent in the enzymatic assays, which allows several antibody measurements on minute samples. In addition antigen decay in vitro was followed and correlated with the antibody response, showing faster disappearance when the latter took place. Time-course studies of the in vitro antibody response demonstrated that precipitating titres are higher and last longer than activating antibody titres. Repeated in vitro challenges showed decay of the memory-potential of in vivo primed lymph nodes, as well as the possibility of inducing an immune response in vitro using non-primed lymph nodes. The results underline the amenability of the present system to the study of in vitro primary and secondary immune responses toward restricted portions of a macromolecule. [ABSTRACT FROM AUTHOR]

Antibody production in the African clawed toad (Xenopus laevis) against Salmonella flagella and the immunochemical properties of the antibodies were studied. The titre of the serum antibodies increased slowly and reached a maximum at 3 weeks after immunization and they were detectable even 20 weeks after antigenic stimulation. No protein components were electrophoretically demonstrated at the region corresponding to the IgG of mammalian antibodies. Two types of antibodies were found; the one produced early after immunization was heat- labile and the other produced later was heat-stable. The former was of low molecular weight (7S component) and the latter was macromolecular (19S component). Both antibodies moved electrophoretically to the cathode and were sensitive to 2-mercaptoethanol (2-ME) treatment, and their antigenicities were not identical. The low molecular weight antibody did not fix complement in the presence of antigen, in contrast to the macromolecular antibody. The low molecular weight antibody did not correspond to the IgG type of mammalian antibodies in the following properties; 2-ME sensitivity, heat-sensitivity, electrophoretic mobility and absence of complement-fixing ability. [ABSTRACT FROM AUTHOR]

A system is described with which an antibody response to soluble chicken ovalbumin can be obtained in dissociated spleen cell cultures from primed mice. This was assayed by determining specific anti-ovalbumin plaque-forming cells (PFC). Only IgG-producing cells (indirect PFC) were seen. The mice received alum-precipitated ovalbumin i.p. and cultures were set up either late in the primary splenic response (23–27 days after injection) or near the peak of the response (10–14 days). With both groups secondary responses were seen in the presence of antigen on the fourth day of culture. In the second group PFC were present in the cultures at a high level initially. The number of PFC de- creased over the first 2 days, the rate of decrease being greater in the presence of antigen. When mice were primed with alum-precipitated ovalbumin together with B. pertussis as adjuvant, responses could not now be obtained in culture. With mice taken late in the primary response (23–27 days), a considerable number of PFC were present in the cultures initially. The number decreased throughout the 4-day period and the decline was accelerated by antigen. With mice taken near the peak of the response (10–14 days) no PFC were seen in culture, even on the first day, in the presence or absence of antigen. The first phenomenon, suppression by antigen, is considered to be of general significance since it may also be seen in cultures from mice receiving no B. pertussis as described. It is suggested that the second phenomenon is due to adverse culture conditions resulting from the white cell mobilization initiated by B. pertussis; after 23–27 days conditions have recovered to a point where suppression but not the secondary response can occur. The suppressive effect of antigen could be related to antigenic competition or tolerance. [ABSTRACT FROM AUTHOR]

In eighty-nine adult Nigerians, with clinical and asymptomatic amoebiasis and in patients with conditions other than amoebiasis, serum concentrations of immunoglobulins (G, A and M) are presented as geometric mean values (mg/ml). Statistical analysis revealed a significant relationship between active symptomatic amoebiasis and raised IgG concentrations in all the groups studied except in pregnant and post-partum states. In contrast, analyses of the IgA and IgM data showed no significant correlation except in males with amoebic dysentery; and in males with amoebic liver abscess in which the respective irnmunoglobulins are significantly raised (Table 1). Estimation of immunoglobulin levels during a follow-up study in fifteen amoebiasis patients showed a tendency for IgG to fail appreciably with treatment of the disease. The role of humoral immune responses in amoebiasis is discussed in the light of the low levels found in pregnancy and post-partum states, when the disease is known to be most severe. [ABSTRACT FROM AUTHOR]

The effect of a single batch of horse anti-mouse thymocyte globulin on the humoral immune response has been extensively investigated in 10-12-weekold male mice of six inbred strains. The preparation under test readily suppressed the primary immune response of A/HeJ, C57B1, DBA/1, CBA and C3H mice to 0.1, 1.0 and 10.0 mg doses of alum precipitated bovine serum albumin (alum BSA). However, at the doses used it generally failed to significantly suppress the primary immune response of BALB/c mice to 0.1 and 1.0 mg doses of this antigen. Furthermore, the effectiveness of the suppression was somewhat diminished by the incorporation of bordetella pertussis organisms into the alum BSA inoculum. The product also suppressed the secondary immune response to alum BSA in C3H mice and C57B1 mice but, at the same doses, was without significant effect on the secondary responses of A/HeJ and CBA mice. [ABSTRACT FROM AUTHOR]

Incorporation of [³H]thymidine into the spleens of intact mice during the primary and secondary responses to SRC has been studied. In both responses, auto-radiographs show a well marked increased incorporation of [³H]thymidine by cells in the peri-arteholar zone during days 1 and 2. The degree of labelling indicated that many of these cells were in S phase in preparation for mitosis. A similar response occurred in cells situated in the mantle layer on day 3 to day 4 of the primary response, but was much less evident in the secondary response. This was in keeping with the results of scintillation counting which showed that increased uptake of [³H]thymidine was more sustained in the primary than in the secondary response to SRC. Many lightly labelled cells indicating metabolic turnover of DNA developed in the red pulp of the spleen at times which coincided with the maximum development of antibody-producing cells (PFC) which occurred about 24 hours earlier in the secondary than in the primary response. Germinal centres showed many lightly labelled nuclei. In both primary and secondary responses these areas enlarged, becoming maximal in size after the peaks of PFC were achieved. It was concluded that the enlargement of germinal centres was the result of trapping of cells in the areas rather than proliferation. From these studies it appears that metabolic turnover of DNA occurred in areas of the spleen intimately associated with antibody formation. The possible role of this process in antibody synthesis is discussed in the light of these observations. [ABSTRACT FROM AUTHOR]

We have investigated the cell populations required for the in vivo and in vitro immune response of mouse spleen cells to rabbit Fab'2 and Fab' and sheep red blood cells (SRBC). The production of IgM antibodies to SRBC both in vivo and in vitro is dependent upon the presence of thymus-derived lymphocytes, although some response does occur in their absence. The IgG response can only be obtained in vivo, and is also dependent upon the presence of thymus-derived lymphocytes. By contrast, the in vivo and in vitro IgM response of mice to rabbit Fab'2 and Fab' is independent of the presence of thymus-derived lymphocytes, but the in vivo IgG response is thymus dependent. The in vitro response to both SRBC and rabbit Fab'2 is low in cultures depleted of macrophages, but the rabbit Fab'2 response appears less affected by macrophage depletion than the SRBC response. [ABSTRACT FROM AUTHOR]

Summary. The major (Group I) allergen of rye grass pollen and two of its allergoids, adsorbed on alumina gel, were injected into three groups of non-allergic humans. In addition m inducing the anticipated blocking antibody (IgG) response, all individuals developed immediate skin hypersensitivity to the allergen and its allergoids characteristic of reaginic antibody-(IgE-)mediated reactions. At some time during the course of the study, virtually every individual's peripheral blood leucocytes were also found to release histamine when challenged in vitro with low concentrations of allergen and allergoids. Quantitatively, each person's skin and leucocyte sensitivities were not as well correlated as in naturally allergic people. Leucocyte responsiveness was generally shortlived, but could be restored by antigenic restimulation. Allergoid:allergen sensitivity ratios were greater in allergen- than allergoid-immunized individuals, but less than in naturally allergic individuals. Unexpectedly, allergoid-immunized individuals' leucocytes were more sensitive to allergen than allergoid. Despite the observed skin and leucocyte reactivities, none of the people showed clinical manifestations of hay fever following natural exposure to pollen. The skin sensitivity of the artificially sensitized individuals could be passively transferred to non-allergic humans by intradermal inject:ion of serum (P-K Test), thereby implicating the involvement of IgE antibody. Further proof of the role of IgE was obtained by blocking the P-K test, either by heating the serum or by adsorbing it using an anti-IgE immunosorbent. [ABSTRACT FROM AUTHOR]

An evaluation of the specificity of antigen binding receptors possessed by cells involved in cellular immune responses and by cells in the antibody synthesizing line was made in order to determine to what extent each cell type could distinguish between closely related mono-ε-DNP-oligo-L-lysines. The antigen binding receptors of cells involved in cellular immune responses were studied by the elicitation of delayed hypersensitivity reactions in vivo and by the stimulation of DNA synthesis by lymph node cells in vitro using 1-ε-DNP-nona-L-lysine and 9-ε-DNP-nona-L-lysine. These experiments demonstrated that closely related compounds could be distinguished by this cell population. On the other hand, serum antibody from animals immunized with 1-ε-DNP-nona-L-lysine did not regularly distinguish between various mono-ε-DNP-oligo-L-lysines of differing immunogenicity or between 1-ε-DNP-nona-L-lysine and 9-ε-DNP-nona-L-lysine. Serum antibody specificity is assumed to reflect the specificity of the receptors possessed by the precursors of antibody producing cells. Thus, it appears likely that the cells involved in cellular immune responses or functioning as 'helper' cells in the stimulation of antibody synthesis by other cells are capable of determining the immunogenicity of a compound. On the other hand, precursors of antibody producing cells, at least in primed animals and in the mono-ε-DNP-oligo-L-lysine response, do not appear to make distinctions between peptides of differing immunogenicity. [ABSTRACT FROM AUTHOR]

The present report describes the morphology of lymphoid tissues and the humoral antibody response during primary and secondary immune responses to sheep erythrocytes (SRBC) in Snell-Bagg hereditary pituitary dwarf mice. It has been found that while 19S primary response was depressed to a great extent, 7S secondary response reached practically normal levels. Histological studies of the peripheral lymphoid tissues have shown patterns of cellular depletion in nonthymus-dependent areas in dwarfs killed during primary response, while these areas appeared markedly cellular after a second antigenic stimulation. It is suggested that the cell systems involved in antibody production during primary and secondary responses to SRBC may be separate and different. As a result, the endocrine imbalance of the dwarf mice affects only the primary response to SRBC. [ABSTRACT FROM AUTHOR]

In the antibody response to rabbit IgG in BALB/c mice, antigenic competition has been demonstrated between Fc and Fab'. Similar competition was found when a mixture of Fc and Fab' was used as antigen. In both cases the presence of Fc suppressed the antibody response to Fab'. Competition was demonstrable only in the primary antibody response. The effect on competition of varying the mutes and the time course of administration of the antigens was investigated. [ABSTRACT FROM AUTHOR]

Formation of aggregates in mixtures of antigen and antibody was followed by measurement of the intensity of light scattered at 90° and of the ratio of the intensities of light scattered at 45° and 135° under varied environmental conditions—concentration, antigen/antibody ratio, temperature, concentration of neutral salts, hydrogen ion and organic solutes. We propose that the aggregation of antigen-antibody complexes is accelerated by change in the structure of antibody molecules that occurs on combination with antigen. The effect of solutes on the rate of aggregation may be due to reduction of the association constant of the combination of antigen and antibody or to inhibition of the change in structure of antibody on combination. Acceleration of the early stage of aggregation by increase of temperature is attributed to increased rate of change in the structure of antibody. [ABSTRACT FROM AUTHOR]

Lepisosteus osseus possesses high titres of natural agglutinins to human group A (HuA) erythrocytes and to Salmonella typhosa 'O' (STO) antigens. Moderate natural haemagglutinin titres to sheep red blood cells (SRBC) were noted. Cold agglutinin (4°) titres exceeded agglutinin titres recorded at 25°. Immunization with STO antigen resulted in a marked increase in corresponding anti-STO agglutinins, as well as increases in anti-HuA and anti-SRBC agglutinins. Animals immunized with SRBC antigen produced elevated anti-SRBC agglutinin titres, while immunization with HuA erythrocytes produced no changes in agglutinin levels. Immunization with STO following previous injections with HuA resulted in increases of corresponding anti-STO agglutinins, as well as marked increases in anti-HuA agglutinins. Absorption studies indicated that anti-STO agglutinins were not cross reactive against HuA antigens. Natural and immune antibodies were all of the same macromolecular class. Rises in antibody titres were reflected in both cold and warm agglutinins. Animals maintained for long periods at low temperatures exhibited preferential ability for increased synthesis of cold agglutinins to HuA. Natural haemolytic titres, as measured by an SRBC indicator system, were also elevated as compared to mammalian systems. These titres increased with stimulation with SRBC. Results suggest that the high levels of natural haemolytic and agglutinin activity in this species are of immunogenic origin. [ABSTRACT FROM AUTHOR]

After injection of several antigens, synthesis of specific antibodies is, in all studied cases, accompanied by synthesis of immunoglobulins unable to react with the antigen. The ratio between non-reactive immunoglobutins and specific antibodies decreases during successive immunizations. The immune response to two different antigens (TMV and BSA) is very similar: antibody levels in the serum and numbers of antibody secreting cells in file spleen of immunized animals are nearly identical. When these two antigens are simultaneously injected in rabbits, each antigen seems to initiate independently proliferation of antibody secreting cells and of non-reactive immunoglobulin secreting cell populations. The meaning of these results is discussed. [ABSTRACT FROM AUTHOR]

The technique of equilibrium density gradient centrifugation has been used to study the antibody forming cells (AFC) produced in the Lewis rat and the toad Bufo marinus in response to polymerized flagellin protein antigen. In both animals the AFC at the peak of the response were heterogeneous in density, and formed many separate peaks, as has been observed previously with sheep erythrocyte antigen. Two lines of evidence suggested the various peaks were of biological significance. The earliest AFC found in the rat spleen were simpler in density profile than the AFC at the peak, although a complex 'steady-state' situation developed soon after. In the toad, a definite sequence of density peaks appeared progressively during the whole response. In the rat, the AFC making different classes of antibody gave different density profiles, and could be partially separated from each other. The density separation technique may be useful for studying the differentiation and maturation of antibody forming cells. [ABSTRACT FROM AUTHOR]

Initiation of an immune response to sheep erythrocytes by the transplantation of spleen cells into irradiated recipients is thought to involve an interaction between two functionally different lymphoid cells. If such populations actually exist, it should be possible to separate them from each other and to study the properties of each type of cell. To this end, mouse spleen cells have been fractionated using equilibrium centrifugation in density gradients of Ficoll. Two functionally different populations of spleen cells were obtained. Neither population was active in initiating an immune response by itself on transplantation into irradiated mice, but mixtures of the two populations were. One population of spleen cells was also active when transplanted together with normal mouse bone marrow and the other population was active when mixed with thymus cells from normal mice. These results indicate that two different spleen cells must interact to initiate an immune response in vivo. The specificity of the cell that synergizes with thymus ceils was investigated further and shown to have antigen-specific receptors on its surface. These cells can be recognized by their ability to make rosettes with erythrocyte antigens. Thus, the ‘background’ rosette-forming cells found in unimmunized mice are actually progenitors of antibody-producing cells. [ABSTRACT FROM AUTHOR]

Dvorak and Flax (1966) and others reported that adult guinea-pigs pretreated with soluble antigens showed depressed immune responses following immunization with the same antigens in Freund's complete adjuvant. These depressed immune responses included haemolytic and cytophilic antibody and delayed hypersensitivity as well as antibody measured by passive cutaneous anaphylaxis and haemagglutination. This communication describes further studies on the effect of pretreatment with alum precipitated bovine γ-globulin rather than soluble antigen. Guinea-pigs given 1 mg of alum precipitated bovine γ-globulin prior to immunization with 50 µg bovine γ-globulin (BGG) in Freund's complete adjuvant show depressed haemolytic and cytophilic antibody and delayed hypersensitivity. This depression is immunologically specific as pretreatment with alum precipitated egg albumin does not depress immune responses to bovine γ-globulin. In contrast, antibody measured by passive cutaneous anaphylaxis and haemagglutination is either unaffected or raised. Similarly, pretreatment with sheep red cells reduces the cytophilic antibody response to sheep red cells in Freund's complete adjuvant. This depression is long lasting and 1 mg alum precipitated BGG depressed the haemolytic antibody response to BGG in adjuvant given 6 months later and the delayed hypersensitivity response to BGG in adjuvant given 9 months later. Alum precipitated BGG given up to 6 days after immunization with BGG in adjuvant caused some depression of haemolytic antibody. However, this depression was transient and much less than the long lasting depression caused by pretreatment with alum precipitated BGG 7 days before immunization with BGG in adjuvant. The effect of irradiation followed by alum precipitated BGG on the immune responses to BGG in Freund's complete adjuvant was also studied. 300 r depressed haemolytic and haemagglutinating antibody but had no effect on cytophilic antibody or delayed hypersensitivity. There was no synergy between irradiation and pretreatment with BGG; the depression of immune responses caused by irradiation followed by alum precipitated BGG was no greater than the depression caused by the more effective agent when given alone. [ABSTRACT FROM AUTHOR]

The primary and secondary immune responses of toads (Bufo marinus) were studied using the bacteriophage f2 as antigen. Antibodies were identified in the serum 2 weeks after primary immunization and peak antibody levels were reached at 6 weeks. Although both IgM and IgG antibodies can be found in toad serum, most of the antibody activity in our animals persisted in the IgM fraction until 8 weeks after immunization. When a second injection of antigen was given 4 weeks after primary immunization, there was a marked increase in the total serum antibody activity and IgG antibodies were found as early as 4 weeks after the second injection of antigen. These observations suggest that the toad, B. marinus, is capable of a true secondary response to the bacteriophage f2. [ABSTRACT FROM AUTHOR]

To study the mechanism of antigenic stimulation in the secondary immune response, primed lymphoid cells were stimulated with antigen in various ways in vitro. The effect of antigenic stimulation was assessed by the antibody titres obtained after in vivo culture of palmed cells in X-irradiated recipients. Primed cells were much more effectively stimulated by antigen-antibody (Ag-Ab) complex than by free antigen. Primed cells could also be stimulated by spleen or lymph node cells from normal mice which had been exposed to free antigen or Ag-Ab complex in vitro or in vivo and thoroughly washed. Under these conditions, Ag-Ab complex was again much more effective than free antigen. When the cells were incubated with Ag-Ab complex, the dose of antigen bound to the cells was somewhat increased. But this increased binding of antigen could not solely account for the increase in immunogenicity. It is suggested that the ingestion of antigen by macrophages is facilitated by the presence of antibody and that the macrophages mediate the effective immune stimulus to memory cells. The effect of antibody in increasing the immunogenicity of antigen was lost completely when antibody was digested with pepsin. Thus, the Fc portion of antibody seemed to be important for this effect. However, it was demonstrated that antibody does not operate by becoming attached to macrophages as cytophilic antibody, and that complement is not involved in this process. The augmenting mechanism of antibody on the antigenic stimulation mediated by macrophages was discussed. [ABSTRACT FROM AUTHOR]

The role of macrophages in the immune response against SRBC in spleen cell suspension cultures obtained from mice was studied. 1. The presence of macrophages increases the number of PFC against SRBC in spleen cell cultures. 2. The ratio peritoneal exudate cells to spleen cells is very critical. Two × 105 peritoneal exudate cells preincubated with sheep red blood cells stimulate 1 × 107 mouse spleen cells to an optimal response. This reaction is suppressed when 2 × 106 peritoneal cells are used. 3. Spleen cell populations which had lost the capability of producing antibodies by elimination of cells adhering to glass yielded a strong immune response upon addition of 2 × 105 peritoneal exudate cells. The significance of macrophages for the induction of the immune response is discussed. [ABSTRACT FROM AUTHOR]

A study has been made in the chicken of the late phase (after the 21st day) of the immunological response to a single intramuscular injection of a soluble protein antigen, human serum albumin (HSA), incorporated in a waterin-oil emulsion with or without heat-killed Mycobacterium tuberculosis. Birds injected with a water-in-oil emulsion showed, after a fall from the initial primary response peak (8-12th day), a second rise in antibody production beginning at the 21st day. Control birds injected with HSA in 0.15 M NaCl failed to show this second rise. The peak of the second phase of antibody production in these experiments fell between the 42nd and 59th days. The results of one experiment showed that in birds injected with Freund's complete adjuvant the average second peak level was 100-fold higher than the average first peak level. However, the second peak level of antibody reached was much higher in birds injected with HSA in Freund's complete adjuvant than in those injected with a simple water-in-oil emulsion. The avidity of anti-HSA present in the second phase of antibody production by birds injected with HSA in water-in-oil emulsions has been compared with the avidity of anti-HSA produced during the first phase (10th day). The avidity of sera obtained during the second phase of anti-HSA production by birds given water-inoil emulsions with or without added M. tuberculosis was much greater than that of sera obtained during the first phase. The anatomical site of antibody production during the second phase of antibody production has been investigated. The findings suggest that, whereas antibody production during the first phase is in the spleen and probably other lymphoid tissues, much of the antibody produced during the second phase may be from the granuloma produced at the site of injection of the water-in-oil emulsion. [ABSTRACT FROM AUTHOR]

The effect of various adjuvant procedures on the antibody response (first 21 days) for human serum albumin (HSA) has been studied in the chicken. The lack of effect on the circulating antibody level contrasts with their action in some mammals. The administration of depôt-type adjuvants failed to increase the peak circulating antibody levels (8-12 days after injection of antigen) by comparison with control birds. However, the circulating antibody level declined more slowly in birds given HSA in a water-in-oil emulsion than in birds given HSA in saline. The administration of endotoxin and 'surface active' adjuvants also failed to increase the peak circulating antibody levels over that of control birds. In three experiments there was significant depression of peak antibody levels in birds given endotoxin adjuvant in comparison to control birds. The administration of HSA in Freund's complete adjuvants containing Mycobacterium tuberculosis or Mycobacterium avium did not result in elevation of peak antibody levels compared to those of control birds given HSA in saline or HSA in a water-in-oil emulsion. Experiments to determine the effect of adjuvants from each of the main groups on the establishment of immunological memory were performed. Chickens were given adjuvant with the primary injection of HSA. A second injection of HSA without adjuvant was given 56 days later. None of the adjuvants used produced an increase in the peak antibody level attained during the secondary response compared to control birds. [ABSTRACT FROM AUTHOR]

The experimental conditions most suitable for use in the assay of serum neutralizing antibody specific for bacteriophage φX174 by a 50 per cent neutralization method were investigated. Although assays conducted at 37° more readily revealed the presence of background neutralizing activity in the serum of non-immunized germ-free and conventionally reared mice, assays performed at 4° were more suitable for use in detecting the development of newly synthesized neutralizing antibody. In definitive experiments, the SD50 values obtained, i.e. the reciprocal of the serum dilution producing 50 per cent neutralization of added bacteriophage, were found to be directly proportional to the concentration of neutralizing antibody present in serum. The magnitude of the SD50 values obtained suggests that the procedure may be employed advantageously for the detection of very small amounts of antibody and in studies dealing with the kinetics of the antibody response. [ABSTRACT FROM AUTHOR]