Alteration of clonal profile. II. Studies on the capacity of BALB/c splenic B cells to perpetuate responsiveness to phosphorylcholine and T 15 idiotypic dominance

Physiology of murine B lymphocytes. II. Life-spans of mitogen and thymus-independent antigen (type 2) reactive B lymphocytes from aged mice

We showed earlier that life spans of murine B lymphocytes could be estimated by measuring the functional reactivities of normal B cells upon transfer into x-linked immunodeficient (xid) mice, which do not respond to anti-mouse IgM (anti-mu) antibodies and thymic-independent type-2 (TI-2) antigens. Here the same approach was adopted, to evaluate the life spans of B-lymphocytes from aged mice. Spleen cells from normal young and aged mice were transferred into young or aged xid recipients and the decay kinetics were followed by measuring the proliferative response to anti-mu and PFC response to TNP-Ficoll, a prototype TI-2 antigen. The results indicated that anti-mu reactive B cells of both young and aged mice decayed with similar non-linear kinetics. About 50% of the donor cells decayed in 8-10 days, whereas, the remaining decayed at a slower rate and it appeared that the median life-expectancy of this latter population could be at least 3 weeks. Essentially, there was no apparent difference in the decay kinetics of anti-mu reactive B cells of young and aged mice. Unlike anti-mu reactive cells, TNP-Ficoll reactive B cells showed 2-3-fold enhancement in the PFC response during the first 2 weeks, and persisted at least until 5 weeks post transfer. This result indicated that TNP-Ficoll reactive B cells are long-lived. Further, it was found that the turn over rate of TNP-Ficoll reactive B cells was also very similar in young and aged mice. The environment of the aged mice also did not appear to have any effect since the survival profiles of anti-mu reactive B cells were the same in young or aged xid recipients. Altogether, these results suggest that aging does not significantly alter the life spans of mature B lymphocytes.

Analysis of human lymphocyte protein expression. I. Identification of subpopulation markers by two-dimensional polyacrylamide gel electrophoresis

This study provides new knowledge on the changes in protein expression that differentiate the functionally and phenotypically different cells of the human immune system. Purification by flow cytometry of normal lymphocytes (both T and B cells), monocytes and granulocytes, combined with high-resolution two-dimensional polyacrylamide gel electrophoresis, revealed reproducible qualitative and quantitative changes between these cell populations. Characteristic profiles of marker proteins for each cell type were identified. Determination of markers for T lymphocyte subpopulations was achieved by the comparative analysis of normal T cells separated on the basis of CD4 and CD8 expression in combination with the analysis of cells from patients with T cell chronic lymphocyte leukemia. These results suggest that the modulation or regulation of proteins is very strictly controlled in lymphoid differentiation, and that several quantitative and a few qualitative differences can give rise to completely different phenotypes. Thus, instead of detecting numerous random differences among lymphocyte protein patterns, rather stringent regulation of protein expression in each subpopulation was found.

Immunocompetence of chimeric rabbits. III. Serial passage and persistence of B-lymphocyte memory

In a model consisting of noninbred rabbits matched for major histocompatibility antigens and mismatched for immunoglobulin allotypes, using cell donors and recipients unrelated to each other, B-cell memory has been demonstrated to persist through three successive transfers for a period approaching 2 years. Memory cells from the original donor are shown to dominate specific antibody responses of the primary and secondary recipients. Vigorous antibody responses by donor-derived cells are obtained even when antigenic stimulation is delayed by several months. The data suggest that B memory cells may be particularly efficient in the colonization of recipients, and the potential significance of these findings for adoptive immunization of human bone marrow recipients is discussed.

Plasma cells and their precursors. IV. Cross-reacting and non-cross-reacting, sheep erythrocyte lysing IgG antibody clones induced in rabbits immunized with rat- and chicken-erythrocytes

Rabbits were i.v. immunized with rat erythrocytes or chicken erythrocytes. The sera were investigated using the IEF technique. A number of the RRBC immunized animals and a high proportion of the CRBC immunized animals contained SRBC-lysing IgG antibody clones in addition to apparently normal anti-RRBC or anti-CRBC antibodies. Intravenous immunization with RRBC, followed by immunization with CRBC, yielded clones of SRBC-lysing IgG antibodies in almost every rabbit tested. By varying the interval between the RRBC- and CRBC injections, we established that the time needed for the RRBC-induced production of the responsible SRBC-specific IgG AFCP is approximately 5 days. These cells show an average functional half-life of 75 days. At least some of the RRBC- and CRBC-evoked SRBC-lysing IgG antibody clones are incapable of lysing either RRBC or CRBC. We suggest that the production of cross-reactive and non-cross-reactive, hetero-specific AFCP provides a natural explanation for the availability of preexistent AFCP responsible for the presence of the "early phase" of the IgG antibody response to several antigens.

Lack of a requirement for idiotype matching: T cells from mice which cannot produce idiotype support idiotype-positive antibody response

A requirement for idiotype matching was reported such that carrier-primed T helper cells from mice, which are unable to produce an idiotype (idiotype-negative) because of genetic reasons or adult anti-idiotype or neonatal anti-mu antibody treatment, did not provide helper function for an idiotype-positive antibody response. We have analyzed the requirement for idiotype matching in the response to phosphorylcholine by using mice which are idiotype-negative because they were injected with anti-idiotype antibody shortly after birth. Carrier-primed T cells from such animals supported idiotype-positive responses when mixed with normal or primed B cell populations and challenged with appropriate antigen; these responses were quantitatively and qualitatively similar to those obtained with T cells from idiotype-positive animals. These results demonstrate no requirement for idiotype matching and suggest that the procedure used to establish an idiotype-negative T cell donor may be decisive in showing a requirement for idiotype matching.

Regulatory idiotypes. T helper cells recognize a shared VH idiotope on phosphorylcholine-specific antibodies

Priming of BALB/c mice with phosphorylcholine-hemocyanin (PC-Hy) induces T helper cells that are detected in splenic fragment cultures responding to immunization with trinitrophenylated PC-binding myeloma proteins, TEPC 15 (TNP-T15) and MOPC 167 (TNP-M167). Trinitrophenylation did not alter the binding site, idiotype, or isotype of the antibodies as demonstrated by binding studies. To assay idiotype-recognizing helper cells, Ly-2.2-depleted T cells from PC-Hy-primed donor mice were transferred to syngeneic athymic mice. Splenic anti-trinitrophenol fragment cultures were prepared from the nude recipients, and the response to TNP-T15 and TNP-M167 was measured by enzyme-linked immunosorbent assay. The number of responding fragments is dependent on the number of transferred primed T cells. The homing efficiency of 51Cr-labeled helper cells into the spleen of nude recipients was determined. The frequencies of T helper cells taken from PC-Hy-primed donors required for a B cell response to TNP-T15 or TNP-M167 were indistinguishable. The fine specificity of the anti-PC idiotype-recognizing T helper cells was studied by adding hapten (PC) or unconjugated myeloma proteins to fragment cultures as inhibitors at the time of immunization. PC and PC-bovine serum albumin, as well as T15 and M167, inhibited the helper function in vitro. Furthermore, free heavy chains of T15 and M167 partially inhibited T help, but free light chains of both idiotypes had no effect. These findings collectively show that T helper cells, induced by priming with antigen, recognize a shared idiotypic determination on T15 and M167 that is part of the PC binding site. The heavy chains of T15 and M167 appears to be the major structural component of this determinant. Evidently, T helper cells can recognize a shared determinant that is present on idiotypically different myeloma proteins. This determinant appears to be conserved throughout evolutionary and somatic mutations. The role of this shared, binding site-related idiotypic determinant as a regulatory idiotype in T-B cell interaction is discussed.

Mice with the xid defect have helper cells for T15 idiotype-dominant anti-phosphorylcholine primary and secondary plaque-forming cells responses

We have examined the abilities of helper T cells from commercially available (CBA/N X BALB/c)F1 (NBF1) xid male and phenotypically normal female mice to help T15+ and T15- B cells to produce thymus-dependent phosphorylcholine (PC)-specific direct plaque-forming cell responses. Carrier-primed T cells from both male and female mice were found (a) to restore T15+ TD responses in congenitally athymic BALB/c mice, (b) to help PC-primed BALB/c splenic B cells produce predominantly T15+ responses, and (c) to provide help for T15+ and T15- PFC responses generated by PC-primed normal F1 splenic B cells. Furthermore, carrier-primed irradiated xid and normal recipients contributed adequate helper activity for T15 dominant responses. We therefore conclude that male and female NBF1 mice are equally capable of helping T15+ responses.

Monoclonal vs. heterogeneous anti-H-8 antibodies in the analysis of the anti-phosphorylcholine response in BALB/c mice

Biological activities of monoclonal A/J antibodies to the T15 idiotype in BALB/c mice were compared to heterogeneous antibodies raised by conventional immunization procedures. Two monoclonal antibodies, AB1-2 and GB4-10, which are of the gamma 1, chi class, appeared to have identical specificities by binding criteria and reacted similarly to conventional antibodies in their abilities to induce neonatal suppression, inhibit plaque-forming cell induction by phosphorylcholine (PC) antigens and to inhibit specifically, anti-PC plaque-forming cells. However, in functional analyses of anti-PC responses in various strains of mice, discrepancies were noted in the T15 responses as defined by monoclonal antibodies and conventional antisera. This heterogeneity was also observed in adult mice suppressed with the GB4-10 monoclonal antibody. These animals eventually produced an anti-PC responses of AB1-2 idiotype but lacking the GB4-10 marker. These results show that the T15 IgM anti-PC response in BALB/c and other strains of mice is heterogeneous and probably consists of a family of clones. Particular clones can be precisely eliminated by the use of appropriate monoclonal antibodies, and the anti-PC response that eventually recovers is still T15+ but lacking the suppressed clones.

Alteration of clonal profile. III. T15 ontogenetic advantages are not sufficient for establishing idiotypic dominance in adoptive transfer

We have examined the ontogeny of BALB/c plaque-forming cell (PFC) responses to phosphorylcholine (PC) from fetal and neonatal liver by using the (CBA/N x BALB/c)F1 transplantation model. In this system, thymus-dependent (PC-keyhole limpet hemocyanin) and thymus-independent class 1 (PC-Brucella abortus, PC-lipopolysaccharide) PC antigens stimulate B cell subpopulations, which functionally emerge early after transfer. Responsiveness to a thymus-independent class 2 antigen, C-polysaccharide extract of a Streptococcus pneumoniae mutant, is acquired later. The response to PC antigens tested initially exhibited T15 dominance. Non-T15 clones, which are not expressed to a great degree in normal BALB/c mice, are inherently slow in their rate of maturation; in adoptive transfer, however, they eventually comprise much of the transplanted anti-PC PFC response. Obviously, the advantages the T15 subset has in ontogeny do not result in idiotypic dominance once the immature cells are removed from the intact BALB/c environment. We discuss possible regulatory mechanisms involved in the alteration of the T15+:T15- ratio.