The feed-back mechanism in immunoglobulin synthesis

Allotype and charge-related differences in the immune response

Rabbits homozygous at the Ab kappa chain allotypic locus (Ab4/Ab4 and Ab9/Ab9) were immunized with negatively and positively charged antigens. The negatively charged antigens were bovine serum serum albumin (BSA; pI = 4.9), ovalbumin (OV; pI = 4.9) and two synthetic polypeptides: copolymer L-glutamic acid L-tyrosine (abbreviated TG; pI = 4.8) and multichain poly (L-tyrosine: L-glutamic acid) poly D-alanine: poly L-lysine (poly L-lysine backbone) abbreviated (TG) --AL; pI = 4.8). The positively charged antigen was hen egg lysozyme (LYS; pI = 10.2). Homozygous Ab9 rabbits responding to negatively charged antigens made less antibody than did Ab4 homozygotes. In contrast, both groups of animals responded equally well to positively charged lysozyme. The relative electric charges of the antibodies were assessed by Sephadex A-50 chromatography. The charge distribution was found to depend on the charge of the eliciting antigen. The positively charged antibodies of Ab9/Ab9 rabbits were not nearly as positively charged as those raised in Ab4/Ab4 rabbits. The difference in average electric charges and in the range of these charges between Ig Ab4 and Ig Ab9 explain quantitative differences in antibody formation in response to negatively charged antigens and may be a contributing factor to the "pecking order", i.e. unequal phenotypic expression of light chain genes in Ab4/Ab9 heterozygotes.

Suppression of VH, C gamma and C mu gene products in rabbits by maternal immunization against IgM allotype and detection of somatic recombinant molecules in these animals

Suppression of the mu-chain allotype Ms16 was obtained in young heterozygous Ms16/Ms17 rabbits by immunizing the Ms17 mother against the paternal Ms16 allotype. Examination of the concentration of the VH and CH allotypes of paternal origin (a2,Ms16 and e14) in the offspring, revealed not only Ms16 suppression but also VH and C gamma allotypic suppression. The degree of suppression for the C gamma markers (4-25-fold decrease) was much less than that for the C mu or VH markers (50-150-fold decrease). The excess C gamma marker (e14) was found to be present for the major part on molecules possessing the VH allotype derived from the homologous allelic chromosome. The pattern of persistence of molecules with the suppressed C gamma marker in the serum is consistent with the idea that these molecules arise by somatic recombination and that the gene order is VH, C mu and C gamma.

In vitro studies on allotype suppression. IV. Abrogation of waning suppression by normal immunoglobulin of the suppressed allotype

The mechanism of allotype suppression in rabbits has been investigated by studying the in vitro immune responses of spleen cells from rabbits in advanced stages of spontaneous recovery from suppression. Whereas the spleen cells from highly suppressed rabbits can be released from their suppressed state only if treated with a combination of antibodies against the non-suppressed type and immunoglobulin (Ig) of the suppressed type, treatment with either of these two components alone suffices to overcome suppression when cells of more poorly suppressed spleen donors are used. The demonstration that suppression can be abrogated by normal Ig of the suppressed type alone, when cells are obtained from rabbits in the final phases of suppression, lends further support to the previously suggested concept that the probable role of this normal Ig in the release phenomenon may be that of neutralizing an effector of allotype-specific repression, possibly involving suppressor cells.

Deletion of b5 immunoglobulin-bearing lymphocytes in allotype-suppressed rabbits

The proportion of peripheral blood lymphocytes with cell surface b5 immunoglobulin (Ig) was compared with serum b5 Ig levels in allotype-suppressed and recovering b5 homozygous rabbits in order to establish the cellular defect in suppression and to determine the relation between lymphocyte membrane Ig and secreted Ig of the same allotype. In rabbits fully suppressed for b5, the absence of circulating b5 Ig is reflected in a complete deletion of b5-bearing lymphocytes. During spontaneous escape from suppression, the appearance of b5-bearing lymphocytes precedes the appearance of detectable serum b5. During recovery from suppression b5-bearing lymphocytes recover rapidly toward normal levels, but circulating b5 levels remain chronically and disproportionately depressed.

Immunological tolerance in vitro: kinetic studies at the cellular level

When normal mouse spleen, cells in suspension are cultured in vitro in the presence of polymer from S. adelaide flagellin, an immune response can be obtained as measured at the level of single antibody-forming cells. Cultures were stimulated with different doses of antigen, ranging from 0.2 ng to 3 microg/ml of tissue culture fluid and it was found that the peak number of approximately 500 antibody-forming cells per 10(6) harvested cells by day 4 was antigen dose dependent, 2-20 ng/ml being the optimal concentration. When more than 1 microg/ml of polymer from S. adelaide together with either 20 ng/ml of polymer from S. waycross or with 4 x 10(6) sheep erythrocytes were placed in the system, unresponsiveness to S. adelaide, but immunity to the other antigens occurred simultaneously. Cells made immunologically tolerant in vitro to S. adelaide H antigens were transferred into syngeneic lethally irradiated recipients and challenged with the same antigen. The adoptive immune capacity in these mice, as measured at the level of the immunologically competent cell was reduced by 80-90% as compared with relevant controls. Attempts to induce low zone tolerance in vitro were without success. To study the kinetics of tolerance induction in vitro, cells were cultured with tolerogenic doses of antigen for various periods of time, washed, and subsequently cultured with immunogenic doses of antigen for 4 days. It was found, that immunological tolerance may be induced to a significant degree in vitro within a period of 15 min. Similar results were obtained when spleen cells were exposed for various lengths of time to tolerogenic doses of antigen but at a temperature of 4 degrees C instead of 37 degrees C. The results are taken as suggestive evidence that the initial step in tolerance induction is related to the direct interaction between the surface of immune competent cells and antigen molecules.

Studies on rabbit lymphocytes in vitro. IX. The suppression of antiallotype-induced blast transformation in lymphocyte cultures from allotypically suppressed donors

The number of lymphocytes transformed in vitro by antiallotype sera in cultures obtained from allotypically suppressed rabbits is significantly less than that induced in cultures from normal rabbits. There is a compensatory increase in the amount of transformation induced by antiallotype sera directed toward the unsuppressed allotype. Thus the control of allotypic expression is suppressed rabbits appears to be the same for lymphocytes and for plasma cells.

Competition of 19S and 7S antigen receptors in the regulation of the primary immune response

Prior to sheep red cells (SRC) mice were given 7S or 19S anti-SRC antibodies or mixtures of both. All 7S preparations suppressed the immune response. All 19S preparations enhanced the primary response, as measured by an up to 15-fold increase in the number of PFC per spleen. Results obtained with mixtures showed that 7S and 19S antibodies are competitive in their effect. The kinetics of the appearance of PFC in the mouse spleen after injection of SRC suggest that the depressive effect of 7S antibody simulates a reduction in SRC dose, whereas the enhancing effect of 19S antibody appears as a temporary increase in the rate at which PFC appear. Antibodies from one animal species are quite effective in another species.

Immunoglobulin synthesis in mice: suppression by anti-allotype antibody

In the mouse, antibody directed against an immunoglobulin allotype, Ig-1b, passed from mother to offspring or injected into neonates, suppresses synthesis of immunoglobulin carrying Ig-1b. In allotype homozygotes as well as heterozygotes the allotype suppression is manifested both by a delay of several weeks in attaining initial detectable allotype levels and a reduction in allotype level continuing into adulthood. A possible mechanism for the differentiation of the immune system consistent with both the kinetics of suppression reported here for the mouse and the comparatively longer lived and more complete allotype suppression described for the rabbit is discussed. Evidence for a strong intralitter (as opposed to interlitter) correlation of age of onset of immunoglobulin allotype synthesis is presented.

Cells as antigen carriers and as immunoglobulin producers. Synthesis of antibody and allogeneic immunoglobulin after transfer of antigen-treated cells to newborn rabbits

The injection into newborn rabbits of a small quantity of human albumin, associated with red blood corpuscles or nucleated rabbit cells, induces an antibody response in the majority of animals, whereas the same quantity of antigen in solution fails to stimulate antibody formation or induces tolerance. The promoting capacity of the cells depends on attachment of antigen to them. The antibody produced after the injection of albumin, associated with nucleated cells, is of recipient origin. However, immunoglobulin carrying the marker of donor cells can be demonstrated in the recipient animals, and may reach serum concentrations similar to those normally present in animals which are heterozygous with respect to the marker. It appears that the antibody-promoting function and the synthetic capacity for allotype are quite distinct and that the period required for allotype formation is very short with mononuclear peritoneal exudate cells and is very much longer with cells from the thymus. The capacity of cells from lymph nodes for sustained allotype formation is less than that of thymus cells but greater than that of mononuclear peritoneal exudate cells.