Defective B cell tolerance in adult (NZB X MZW)F1 mice.

Hapten-specific tolerance was induced in vitro by trinitrophenyl-human gamma globulin (TNP32HGG) to a comparable degree in B cells from adult autoimmune (NZB X NZW)F1 (B/W) mice and normal BDF1, CBA/J, and DBA/1J mice. When a lower epitope density tolerogen (TNP7HGG) was used, B/W mice were significantly less sensitive than normal mice to the induction of B cell tolerance. This finding of defective B cell tolerance in adult B/W mice is consistent with previous reports that document other B cell abnormalities that may relate to the expression of autoimmune disease.

Immunomodulatory effect of procainamide in man. Inhibition of human suppressor T-cell activity in vitro.

Procainamide (PA) induces the production of a number of autoantibodies in a high proportion of treated individuals and in some a syndrome closely resembling systemic lupus erythematosus. The mechanism underlying this action of PA is unclear. To examine the possibility that PA might induce autoantibody formation by altering normal immunoregulatory mechanisms, the action of this drug on an in vitro model of antibody formation in man was examined. PA was found to augment the generation of immunoglobulin-secreting cells (ISC) from human peripheral blood mononuclear cells (PBM) in response to pokeweed mitogen but had no effect on pokeweed mitogen-induced tritiated thymidine incorporation. When purified populations of B and T cells were used, PA enhanced the generation of ISC in B-cell cultures supported by untreated T cells but not by T cells treated with mitomycin C. These results indicate that PA augmented B-cell responses by inhibiting suppressor T-cell activity and not by augmenting helper T-cell or B-cell function. N-Acetyl-procainamide had no effect on the generation of ISC in this system. The effect of PA on concanavalin A (Con A)-induced suppressor cell activity was also examined to determine whether PA altered the generation or expression of suppressor T-cell function. PBM were cultured with 30 microgram/ml of Con A for 48 h to generate suppressor cells. When these were co-cultured with fresh PBM, the number of ISC generated was decreased by 58.1 +/- 3.4% (mean +/- SEM, n = 6). Cells that had been similarly incubated without Con A were not inhibitory. The addition of PA to the Con A-stimulated cultures inhibited the generation of suppressor cells as indicated by the fact that the response of fresh cells co-cultured with the Con A-stimulated cells was diminished by only 27.2 +/- 4.3%. In this system too, N-acetyl-procaimamide had no effect. By contrast, adding PA only to the co-culture of Con A-stimulated cells with fresh PBM had a less marked effect on suppressor cell function. These results indicate that the major action of PA is to inhibit the generation of suppressor T-cell activity. Such an effect may explain the capacity of this agent to induce autoantibody formation in treated individuals.

Transient expression of pentameric IgM on the surface of NZB B cells.

In contrast to normal B lymphocytes, splenic B cells from autoimmune NZB mice express on their surface greater amounts of IgM than IgD. We have found that the predominant mu chain species present on these cells is derived from pentameric secretory IgM which can be radioiodinated during transient association with the cell membrane. If the contribution from 19S IgM is discounted, then the surface IgM:IgD ratio of NZB mice is only moderately higher than that of B cells from normal strains.

Regulation of B cell tolerance by macrophage-derived mediators: antagonistic effects of prostaglandin E2 and interleukin 1.

A role for prostaglandins in the mechanism of B cell tolerance induction in normal adult mouse spleen cells was examined. Two inhibitors of the cyclooxygenase pathway of arachidonic acid metabolism, indomethacin and acetylsalicylic acid, abrogated hapten-specific B cell tolerance induction by trinitrophenyl-human gamma-globulin. Tolerance was fully restored by the addition of prostaglandin E2 (PGE2) at a concentration of greater than or equal to 6 nM. T cell-depleted spleen cells produced comparable amounts of PGE2 in culture, indicating that the tolerance promoting activity of PGE2 occurred with physiologically relevant concentrations. Depletion and reconstitution experiments indicated that macrophages in the spleen cell preparations completely accounted for both PGE2 production and the effects of indomethacin and acetylsalicylic acid on B cell tolerance induction. The macrophage product interleukin 1 (IL 1) was also found to alter B cell susceptibility to tolerance induction. Thus, human IL 1 containing monocyte supernatants and purified IL 1 were found to interfere with B cell tolerance induction when added to macrophage- and T cell-depleted splenic B cells. Tolerance was restored in such cultures by the addition of 10 nM PGE2. These experiments demonstrate that within mixed lymphoid populations macrophages through the release of mediators modulate B cell susceptibility to tolerance induction.

Defective B-cell tolerance in New Zealand black mice. Fc receptor-independence of resistance to low-epitope-density tolerogens.

Trinitrophenyl (TNP) human gamma-globulin with low-epitope-density tolerizes B cells from normal BDF1 mice in a Fc gamma receptor-dependent manner but does not tolerize B cells from preautoimmune NZB mice. In order to investigate the relationships between tolerance induction and epitope density independently of Fc gamma receptor function in these two strains, TNP conjugates of two additional thymic-independent tolerogenic carriers, D-glutamic acid-D-lysine (D-GL) and carboxymethyl cellulose (CMC), were tested. A brief pulse with low-epitope-density conjugates such as TNP4.4-D-GL rendered unfractionated or T-cell-depleted spleen cells from BDF1 but not NZB mice tolerant in a hapten-specific manner. Spleen cells from NZB mice, however, were susceptible to tolerization with TNP13.5-D-GL. NZB mice were also resistant to tolerance induction in vivo with TNP5.5-D-GL, TNP3-CMC, and TNP6-CMC, all of which tolerize BDF1 mice in vivo. Both strains were tolerized with TNP13.5-D-GL and TNP13-CMC in vivo. NZB mice were also significantly less susceptible to tolerance induction with TNP3-CMC when TNP-Ficoll was substituted for TNP Brucella abortus as the challenge antigen. These findings militate against the possibility that an Fc gamma receptor defect is the principal mechanism of resistance of NZB B cells to tolerance induction with-low-epitope density conjugates.

Defective B cell tolerance induction in New Zealand black mice. I. Macrophage independence and comparison with other autoimmune strains.

B cell unresponsiveness was examined in vitro by using spleen cells from autoimmune NZB, BXSB/Mp male, MRL/Mp-Ipr/Ipr (MRL/l), and control mice, and the tolerogen trinitrophenyl human gamma-globulin (TNP-HGG). The B cell subset responsive to TNP-Brucella abortus in each autoimmune and control strain that was tested was highly susceptible to tolerance induction with the use of high epitope density conjugates (TNP30HGG and TNP32HGG). When a tolerogen with a lower epitope density was used (TNP7HGG), several control strains were all rendered tolerant in a thymic-independent and hapten-specific manner. NZB B cells were resistant to all concentrations of TNP7HGG tested, whereas B cells from BXSB/Mp male and MRL/1 mice were resistant to low concentrations of this tolerogen. NZB mice were resistant in addition to tolerance induction with TNP9HGG, TNP10HGG, and TNP12.7HGG. Experiments were performed to determine whether splenic macrophages played a role in resistance to tolerance in NZB mice. The mixing of NZB and control DBA/2J T cell-depleted splenocytes revealed no modulatory effects by the accessory cells in culture. Moreover, B cells rigorously depleted of macrophages by double Sephadex G-10 column passage exhibited characteristic patterns of resistance or susceptibility in NZB and control strains, respectively. These findings support the conclusion that resistance to tolerance in NZB mice is determined at the B cell level and are consistent with the hypothesis that diverse immunoregulatory disturbances contribute in varying degrees to the development of systemic lupus erythematosus in different inbred strains of mice.

Ontogeny of susceptibility of mouse splenic B cells to tolerance induction in vitro by TNP-D-GL.

The susceptibility of mouse spleen cells to hapten-specific tolerance induction of a primary in vitro thymus-independent antibody response was examined. Both the induction of tolerance by 2,4,6-trinitrophenyl-D-glutamic acid-D-lysine (TNP96D-GL) and of antibody formation (elicited by TNP-Brucella abortus) in neonatal spleen cell cultures were unaffected by anti-Thy-1.2 plus complement treatment. Spleen cells from neonatal mice were only slightly more sensitive to TNP96D-GL tolerance induction than were cells from adult mice. The difference in susceptibility to tolerance induction was not nearly as great as that predicted by "clonal abortion"-type theories of B cell tolerogenesis.

Lyme disease.

Although initially considered a localized epidemic form of arthritis. Lyme disease is now known to have protean manifestation (skin, joint, heart, nervous system) and worldwide distribution. It is caused by infection with the spirochaete Borrelia burgdorferi and is transmitted by a variety of hard ticks and, in some localities, fleas. Antigenic variation between isolates may determine the differences in clinical expression observed between cases in North America and Europe. The reservoir in the animal kingdom is primarily in deer and mice but house pets have also been implicated. The disease is easily treated with oral antibiotics (tetracycline or penicillin) at an early stage but requires parenteral penicillin and can become refractory to medication at late stages. Prompt diagnosis assures the best outcome. Whereas the classic rash, erythema chronicum migrans, is pathognomonic, diagnosis in its absence may rest on serological tests. Bacteriological isolation is seldom successful and is lengthy (Shrestha et al, 1985). Since cloning of the DNA for several of B. burgdorferi antigens has been accomplished, utilization of hybridization techniques may allow rapid detection of the presence of the organism and confirm difficult cases in the future.

The ontogeny of thymic independent antibody responses in vitro in normal mice and mice with an X-linked B cell defect.

The primary in vitro antibody response of neonatal spleen cells to three thymic independent antigens has been examined. The time of onset of responsiveness to TNP-Brucella abortus and TNP-lipopolysaccharide was significantly earlier than the onset of responsiveness to TNP-Ficoll. This ontologic sequence was not affected by T cell depletion or antigen presentation on adult macrophages. In neonatal mice bearing the X-linked CBA/N defect, the response to TNP-Brucella abortus and TNP-lipopolysaccharide was much delayed and no response to TNP-Ficoll developed. We conclude that different thymic independent antigens address different subpopulations of B cells, one of which appears earlier in ontogeny than the other.