| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1988: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1987: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
The structure and function of Lyb-2 and the mechanisms of B cell activation mediated by B cell stimulatory factor-1 (BSF-1/IL-4) were investigated. The followings were the summary of the results. 1. Role of Lyb-2 in immunoglobulin class regulation by BSF-1. Lyb-2 antibody greatly reduced IgGl induction initiated by LPS and BSF-1 by the action on processes triggered by BSF-1. Limiting dilution analysis revealed that Lyb-2 antibody reduces the procursor frequency but not the clone size of BSF-1-induced IgGl-producing cells. Furthermone, it was shown that this regulation occurred at the transcriptional level of IgGl gene. These and our previous results indicate that the Lyb-2 plays a critical role in B cell differentiation mediated by BSF-1. 2. Structural features of Lyb-2. SDS-PAGE analysis of lysates of surface-iodinated splenic B cells immunoprecipitated with Lyb-2 antibody showed that the lyb-2 molecule is composed of two molecular species. One species is a disulfide-linked heterodimr of 45 kD and 105 kD chains, and the other seems to be a homotrimer of 45 kD chain. 3. Identification of second messengers in BSF-1-mediated signaling events. With Ia-inducing activity of BSF-1 as a readout system, blocking experiments were performed with various inhibitors such as protein kinase inhibitors, Ca ion channel blockers, intracellular Ca ion antagonists, Calmodulin antagonists, and Na^+/H^+ antiport inhibitors. In the event, Ia induction by BSF-1 was inhibited only by TMB-8, an intracellular Ca ion antabonist. Thus, it may be that BSF-1 action is mediated by a minute amount of Ca ion released from the intracellular store, which cannot be detected by the present methodology.
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