Regulation of in vitro immunoglobulin secretion in healthy individuals and multiple sclerosis patients

Mitogen driven differentiation of mononuclear cells is a useful model of antibody synthesis and secretion in humans. We have studied Pokeweed mitogen (PWM) induced immunoglobulin secretion in vitro in both healthy individuals and multiple sclerosis patients. Within the healthy population we have identified individuals who consistently secrete low levels of IgG in response to PWM and others who secrete very high levels. The underlying mechanisms involved in low response are not well understood. We have observed that the peripheral blood mononuclear cells (PBMC) obtained from low responders differ from those obtained from high responders in each of the following: Their T-helper cell subset contains a higher ratio of T suppressor-inducer cells over T helper-inducer cells; their PBMC contain a higher level of in vivo radiation-sensitive suppression; their PBMC generate a lower autologous mixed lymphocyte response; and their B lymphocytes secrete lower amounts of IgG when mixed with heterologous high responder T helper cells. These results suggest the response involves the interactions between T helper cell subsets, T suppressor cells and B lymphocytes and that the level of response is the sum of the contribution of each subset. PWM induced immunoglobulin secretion was measured in multiple sclerosis patients during different phases of clinical disease activity. Relapsing-remitting multiple sclerosis patients in early relapse secreted less immunoglobulin than patients with prolonged relapse, suggesting that immune function varies with clinical disease activity. Testing the level of PWM induced immunoglobulin secretion in relapsing-remitting multiple sclerosis patients during the clinically stable phase suggested that those patients who secreted high levels of IgG in response to PWM were more likely to suffer a clinical relapse within 6 months than those patients who secreted a low amount. Chronic progressive multiple sclerosis patients secreted higher amounts of immunoglobulin in this assay than healthy control individuals. This group of multiple sclerosis patients also had; (i) reduced Concanavalin A (Con A) suppressor cell activity measured both by the ability to suppress a/ Con A induced proliferation and b/ PWM induced IgG secretion in heterologous cell cultures and; (ii) reduced percentages of T cells expressing T suppressor and T suppressor-inducer markers. The treatment of chronic progressive multiple sclerosis patients in vivo with lymphoblastoid interferon resulted in a dramatic reduction in level of PWM induced immunoglobulin secretion without alteration in Concanavalin A induced suppression or in the percentages of T cells expressing subset specific markers. The PWM induced IgG secretion assay is a valuable technique for investigating the regulation of humoral immunity in both health and disease.Medicine, Faculty ofPathology and Laboratory Medicine, Department ofGraduat

Probiotic Preparation VSL#3 Alters the Distribution and Phenotypes of Dendritic Cells within the Intestinal Mucosa in C57BL/10J Mice1–3

Probiotic nutrients have shown promise in therapy for the treatment of gastrointestinal inflammation, infection, and atopic disease. Intestinal dendritic cells (DC) play a critical role in shaping the intestinal immune response. In this study, we tested the effect of a probiotic preparation (VSL#3) on DC distribution and phenotypes within the intestinal mucosa using a lineage depletion-based flow cytometric analysis. In naïve C57BL/10J mice, intestinal mucosal DC were composed of plasmacytoid DC (pDC) and myeloid DC (mDC). The pDC were the dominant form in lamina propria and Peyer's patches, whereas mDC were the prevailing type in the mesenteric lymph nodes. Additional characterization of pDC and mDC with flow cytometry revealed that they expressed heterogeneous phenotypes in the intestinal mucosa. In mice gavaged with the probiotic VSL#3 for 7 d, the proportion of pDC within the lamina propria was >60% lower, whereas the pDC subset in the mesenteric lymph nodes was more than 200% greater than in sham-treated controls (P < 0.01). Within pDC, the proportion of functionally unique CX3CR1+ DC was greater than in controls in both the lamina propria and the Peyer's patches (P < 0.01). In contrast to pDC, the mDC number was greater than in controls in all intestinal lymphoid tissue compartments in VSL#3-treated mice (P < 0.01). In conclusion, this study suggests that phenotypically and functionally distinct DC subsets are localized to specific lymphoid tissues within the intestinal mucosa and that the VSL#3 probiotic nutritional supplement alters the distribution of the DC subsets within the intestinal mucosa. These changes may be important in the alteration of mucosal immunity following probiotic VSL#3 therapy