Maternal B lymphocytes specific for paternal histocompatibility antigens are partially deleted during pregnancy.

Although genetically different from its mother, a mammalian fetus bearing paternal alloantigens is normally not rejected. To investigate one of the many possible mechanisms involved in this important biologic phenomenon, we analyzed the consequences of fetal alloantigen recognition on maternal B lymphocytes. We used transgenic mice expressing a unique B cell receptor with a relatively high affinity for the MHC class I molecule H-2Kk on most B lymphocytes. We provide the first evidence for an alloantigen-specific B cell deletion in the spleens and bone marrow of transgenic mothers bearing H-2Kk-positive fetuses. This highly reproducible deletion affects < or =80% of Id-bearing B cells, starts at midpregnancy, and is only observed until term. Such a specific maternal B cell deletion could contribute to the success of the fetal allograft.

Structure of the polyglutamyl chain of tubulin: occurrence of alpha and gamma linkages between glutamyl units revealed by monoreactive polyclonal antibodies.

Polyglutamylation, a posttranslational modification which consists of the sequential addition of one to six glutamyl units in the carboxy-terminal domain of both tubulin subunits, is a major event in neurons. Its structure has been investigated by using monoreactive polyclonal antibodies directed against distinct glutamylation motifs, ie alpha- and gamma-linkages between glutamyl units. It is shown that, beside alpha-linkages previously characterized, gamma-linkages also occur in glutamyl chains of brain tubulin. The co-existence of these two basic motifs leads to a conception of the polyglutamyl chain with a very sophisticated structure which could, through its complexity, help the microtubule to reach its structure and fulfil its functions.

Trypanosoma cruzi infection enhances polyreactive antibody response in an acute case of human Chagas' disease.

The kinetics of antibody response in an acute case of human Chagas' disease was investigated. Hypergammaglubulinaemia appeared at day 17 of infection, and persisted after 66 days of infection, at which time parasitaemia became undetectable. Titration of immunoglobulins showed that the three principal isotypes were involved in the response, emphasizing polyclonal B cell activation. Total IgA was detected before total IgM, and the latter before total IgG. High titres of autoantibodies were found among IgM and IgG subclasses. IgA was also the first isotype to be detected among specific anti-Trypanosoma cruzi antibodies. However, the maximal parasite antibody response was attained after 30 days of infection for all isotypes. With regard to possible cross-reactivity between molecules of host and parasite, adsorption experiments on T. cruzi-specific immunosorbent were designed. Specific antibodies, present in the eluates, also recognized natural antigens, especially laminin. In order to characterize the alpha-galactose epitope of laminin, adsorption experiments on sheep erythrocytes were performed, and revealed the possible presence of another epitope on the glycoprotein. Our results indicate that in the case of Chagas' disease investigated here, polyclonal activation occurred; moreover, they suggest that molecular mimicry may play a role by increasing autoantibodies, probably via a parasite-driven mechanism.

Simultaneous presence, in one serum, of four monoclonal antibodies that might correspond to different steps in a clonal evolution from polyreactive to monoreactive antibodies.

Three monoclonal IgG of different subclasses (IgG1, IgG2, and IgG4) and one IgA1 were isolated from the serum of patient Per suffering from an immunocytic sarcoma. All four monoclonal Ig shared the same N-terminal sequence of their H chains (VH3). Furthermore, their kappa-chains exhibited identical isoelectric charges and N-terminal sequences (VK2) and expressed the same private idiotope. A strong antitubulin activity was found in IgA1Per and in two of the three monoclonal IgGPer. The specificity was restricted to tubulin for IgA1Per and IgG4Per, whereas IgG1Per also displayed significant polyreactive bindings and IgG2Per failed to react with any of the Ag tested. The monoreactive IgG4Per, as well as the polyreactive IgG1Per, bound a large peptide in the central part of both alpha and beta subunits of tubulin (amino acid position 100 to 300). In contrast, the monoreactive IgA1Per bound to a rarely detected epitope close to residue 310 of these subunits. The tubulin epitope recognized by polyreactive IgG1Per was similar to that of germ-line-encoded polyreactive antibodies. It is hypothesized that IgG4Per- and IgA1Per-producing cells derive from the IgG1Per polyreactive clone after somatic events leading to the production of monoreactive antibodies.

[Immunologic abnormalities in pigs with hog cholera virus infection (author's transl)]. / Modifications des réactions immunitaires au cours de la peste porcine classique.

The effects of an acute Hog Cholera Virus (HCV) infection upon immune functions of experimentally infected pis were studied. Leukopenia was found to occur in both vaccinated and non-vaccinated infected animals but without any decrease in lymphocyte proportion. Lymphocytes from infected pigs had an altered response to phytohemagglutinin (PHA) as judged by an in vitro tritiated thymidine uptake of PHA-stimulated lymphocyte cultures. The beginning of a secondary humoral immune response to lysozyme appeared to be significantly depressed in HCV diseased animals.

Partial inhibition of the humoral immune response of pigs after early postnatal immunization.

The ability of young pigs to be immunized during the postnatal period was studied. Eight groups of pigs born on the same day from 3 sows were injected with hen egg-white lysozyme in Freund's incomplete adjuvant at days 0, 1, 2, 3, 4, 5, 7, and 10 after birth. The serum antibody titers were determined each week. Results indicated that pigs injected within the first 3 days of life exhibited a delay of 10 days in the appearance of the humoral antibodies, compared with the antibody response observed in pigs injected later. Serum antibody titers were markedly lower in the early immunized pigs. The secondary immune response was similar in all pigs. This partial inhibition is not directly linked to the corticoids present in the serum at the immunization day. Possible reasons for this impairment of the humoral immune response were reviewed.

[Adjuvant effect of Quil-A on the porcine humoral immune response (author's transl)]. / Etude de l'effet adjuvant du Quil-A sur la réponse immunitaire humorale chez le porc.

Quil-A, a purified extract of saponin, was analyzed for its adjuvant properties in the porcine humoral immune response against lysozyme. The adjuvant properties of Quil-A are comparable to the oil adjuvant properties in the pig. The optimal dose was found to be 1 mg per pig. Quil-A enhanced also slightly the homocytotropic antibodies.

Heat sensitivity of porcine IgG.

The sensitivity to heat of porcine IgG was studied. The serum from immunized pigs was heated at 56 degrees C for 30 min as for decomplementation. The elution pattern of the serum proteins on an agarose gel column showed a dramatic change with the appearance of a large peak of the gel-excluded material. This peak contained mainly IgG molecules which still retained its antibody activity. This fact points to misinterpretations which can easily occur in 7S and 19S antibody recognition during the porcine immune response. Correlation is suggested of this property with the large number of interheavy chain disulfide bridges present in porcine IgG.