B CELLS AND ACQUIRED T CELL IMMUNITY

我们最近发现补体（C）在迟发型超敏反应（DTH）和接触敏感性（CS）中的作用。这使我们发现了B细胞的作用。现在我们将研究B细胞亚群和参与的IG同种型。B-1 B细胞亚群可能通过分泌IgM发挥作用，IgM可激活C，可能导致局部T细胞募集，特别是在致敏后早期（1-4天）。我们还将探索B-2细胞IgG 2a和IgG 2 B b C激活抗体，以及B细胞APC功能。具体目标#1.鉴定所需的B细胞亚群。将FACS纯化的正常B-1与B-2细胞转移到全B细胞缺陷型JH-/-小鼠中。为了确定重组B细胞是否在激发期起作用，我们还将免疫B细胞亚群转移到已经致敏的JH-/-小鼠中，然后激发皮肤。还将使用表达显性B-1与B-2细胞的辐射嵌合体。具体目标#2.确定CS中B细胞的特性。如果B-1细胞优先参与，我们将确定它们是否是Thy-1+，这可能是通过活化的NK 1.1+细胞早期释放IL-4诱导的，活化的B-1细胞可能从腹膜迁移到淋巴结，并可能具有不同的V区和更高的Ag亲和力。具体目标#3.确定B细胞在CS中的功能。将在具有IG+ B细胞但没有分泌型IG的突变小鼠中探索APC功能。IgM的可能参与将通过使用仅缺乏分泌的IgM的突变小鼠来确定。如果它们缺乏CS，我们将尝试用纯化的IgM mAb重建。更确切地说，我们将在相关特异性IG同种型的JH-/-中创建转基因，以尝试CS重建。最后，我们将使用抗TNP IgM突变体杂交瘤细胞系，以确定Fc部分中哪些氨基酸残基是DTH所必需的。总结。我们的实验将确定参与DTH的B细胞亚群和IG同种型，以及B细胞是否在传入和/或激发阶段起作用。假定B-1细胞的独特参与是B细胞参与的一部分。这些研究带来了关于抗体在引发T细胞免疫中起作用的新想法，并且可以通过天然免疫（B-1细胞IgM）提供的连接将先天免疫（C）与获得性T细胞免疫（DTH）独特地连接。由于DTH是体内T细胞反应性的核心，这些研究可能对深入了解T细胞疾病和免疫抵抗很重要，因此可能对人类健康具有广泛的适用性。

We recently found a role for complement (C) in delayed-type hypersensitivity (DTH), and in contact sensitivity (CS). This led to our finding a role for B cells. Now we will investigate B cell subsets and Ig isotypes that are involved. The B-1 B cell subset likely plays a role by secreting IgM, that may activate C, possibly leading to local T cell recruitment, especially early after sensitization (1-4 days). We also will explore B-2 cell IgG2a and IgG2b C-activating antibodies, and B cell APC function. SPECIFIC AIM #1. To identify needed B cell subsets. FACS purified normal B-1 vs B-2 cells will be transferred into pan B-cell deficient JH-/- mice. To determine if reconstituting B cells act at the elicitation phase, we also will transfer immune B cell subsets into already sensitized JH-/- mice, and then challenge the skin. Radiation chimeras that express dominant B-1 vs B-2 cells, also will be used. SPECIFIC AIM #2. Determine properties of B cells in CS. If B-1 cells are preferentially involved, we will determine if they are Thy-1+, that may be induced via an early release of IL-4 from activated NK 1.1+ cells, and activated B-1 cells may possibly migrate from peritoneum to lymph nodes, and potentially have diverse V regions, and higher Ag affinity. SPECIFIC AIM #3. Determine how B cells function in CS. APC function will be explored in mutant mice with Ig+ B cells, but no secreted Ig. The possible involvement of IgM will be determined by employing mutant mice that just lack secreted IgM. If they are deficient in CS, we will attempt reconstitution with purified IgM mAb. More definitively, we will create transgenes in JH-/- of relevant specific Ig isotypes, to attempt CS-reconstitution. Finally, we will use anti-TNP IgM mutant hybridoma lines, to determine which amino acid residues in the Fc portion are essential for DTH. IN SUMMARY. Our experiments will determine the B cell subset(s) and Ig isotype(s) involved in DTH, and whether B cells act in the afferent, and/or the elicitation phase. Unique participation of B-1 cells is postulated, as one part of B cell involvement. These studies bring new ideas about antibodies acting in eliciting T cell immunity, and may uniquely connect innate immunity (C), with acquired T cell immunity (DTH), via linkage provided by natural immunity (B-1 cell IgM). Since DTH is central to in vivo T cell reactivity, these studies may be important to an indepth understanding of T cell diseases and immune resistance, and thus may have wide applicability to human health.