Shigehiro Motoi

Studies on B‐Cell Memory

Effects of LPS on primary and secondary antibody responses to typical TI‐2 antigens were investigated in mice. Simultaneous injection of LPS with a TI‐2 antigen showed only little adjuvant effect on the following primary antibody response to the antigen. In contrast, either a single or multiple injections of LPS, prior to the immunization with a TI‐2 antigen, significantly augmented the following primary antibody response to the antigen. LPS, however, inhibited the development of B‐cell memory to a TI‐2 antigen when administered together with the antigen. Moreover, an injection of LPS in mice, which had strong IgM and IgG B‐cell memories to a TI‐2 antigen, caused disappearance or profound reduction of the memories. The results suggest that LPS produced by gram‐negative bacteria exerts inhibitory effects on the development and continuation of B‐cell memory to bacterial infections.

Endoscopic studies on the minute structures of colonic mucosa in the follow-up observation of ulcerative colitis

SummaryThirty cases of ulcerative colitis were examined endoscopically by means of magnifying colonoscope with dye spraying method (the combined method), and their minute mucosal structures were classified into four categories endoscopically, which correlated well with the histological findings. By this procedure, it was easy to detect the subsidence of inflammation of the mucosa in the quiescent phase or to reveal the active inflammatory involvement of the bowel. Moreover, inspecting the minute changes of the colonie mucosa detected by the combined method, remission was more correctly decided and rigid control is contributing to the decrease in the recent rate of recurrence of ulcerative colitis.

Effect of aging on immunological memory in gastrointestinal tract induced by sheep red blood cells in mice

SummaryTolerance induction by oral administration of sheep red blood cells (SRBC) was investigated in young and aged mice. Two-month old C3H/He mice receiving oral administration of 8xl09 SRBC a day for two weeks became tolerant to a subsequent SRBC challenge in the systemic immune system. In contrast, older C3H/He mice aged about 1 year old receiving the same treatment did not become tolerant but resisted tolerance induction and produced a prominent IgG memory in the systemic immune system. Autoimmune-prone NZB mice showed a similar resistance to tolerance induction even at 3 months of age. To investigate a possible role of the liver in the oral tolerance induction, young (2-month old) C3H/He mice received an injection of lxl08 SRBC via portal vein. The mice thus treated, were not tolerized at all but immunized.The results suggest that gut-associated local immune system play a key role in the induction of the oral tolerance and that the tolerance inducing function of the local immune system declines with aging. Antigens in the gut including denatured self antigens may immunize the systemic immune system of aged animals.