Forsdyke D R
Immunology. 1973 Oct;25(4):597-612.
Lymph node cells from preimmunized rabbits were cultured with varying concentrations of antigen in autologous serum which had been collected before immunization. [H]Thymidine was added after 18 hours of culture and the cells were harvested at 24 or 66 hours for the determination of the radioactive labelling of acid-precipitable material. Preheating serum (56°, 20 minutes) enhanced labelling in both control and antigen-treated cultures. This `heat effect' had an early (24 hour) non-specific component, independent of antigen concentration, and a late (66 hour) specific component which was most evident at high antigen concentrations. The conditions of preheating serum (temperature and time) required to produce the heat effect were similar to those required to remove haemolytic activity against rat erythrocytes. However, at certain temperatures and times there were discrepancies. These discrepancies, and data from experiments in which preheated and unheated sera were mixed in varying proportions, or interchanged in different sequences, were explicable on the basis of (i) a requirement for complement in stoichiometric quantities dependent on the number of cells being inhibited, (ii) the involvement of the majority of the cultured cells in the early non-specific component of the heat effect, but only cells capable of proliferating in response to added antigen in the late specific component, (iii) the secretion of complement by cultured cells. Preheating serum (66°, 20 minutes) depressed labelling in control and antigen-treated cultures and reduced agglutinating activity against both autologous and heterologous erythrocytes. The results are discussed in relationship to models which require that the size of a specific lymphocyte clone be positively or negatively regulated by the concentration of antigen specific for that clone. With increasing antigen concentration three effects on cells bearing specific receptor sites are distinguished. (i) Cell stimulation under conditions of antigen concentration and cell receptor specificity such that only a few antigen molecules can bind to cells. (ii) Complement-dependent inhibition under conditions such that more antigen molecules can bind to cells. (iii) Complement-independent inhibition under conditions, possibly unphysiological, such that very large quantities of antigen molecules can bind to cells.
将免疫前兔子的淋巴结细胞与不同浓度的抗原在免疫前采集的自体血清中进行培养。培养18小时后加入[H]胸腺嘧啶核苷，在24或66小时收获细胞，用于测定酸沉淀物质的放射性标记。预热血清（56℃，20分钟）可增强对照培养物和抗原处理培养物中的标记。这种“热效应”有一个早期（24小时）非特异性成分，与抗原浓度无关，还有一个晚期（66小时）特异性成分，在高抗原浓度下最为明显。产生热效应所需的预热血清条件（温度和时间）与去除对大鼠红细胞的溶血活性所需的条件相似。然而，在某些温度和时间存在差异。这些差异以及将预热和未预热血清以不同比例混合或按不同顺序互换的实验数据，基于以下几点可以解释：（i）依赖于被抑制细胞数量的化学计量的补体需求；（ii）大多数培养细胞参与热效应的早期非特异性成分，但只有能够对添加抗原作出反应而增殖的细胞参与晚期特异性成分；（iii）培养细胞分泌补体。预热血清（66℃，20分钟）会降低对照培养物和抗原处理培养物中的标记，并降低对自体和异源红细胞的凝集活性。结果结合了要求特定淋巴细胞克隆大小受该克隆特异性抗原浓度正向或负向调节的模型进行了讨论。随着抗原浓度增加，区分了对带有特异性受体位点的细胞的三种效应。（i）在抗原浓度和细胞受体特异性条件下的细胞刺激，使得只有少数抗原分子能与细胞结合。（ii）在更多抗原分子能与细胞结合的条件下的补体依赖性抑制。（iii）在可能非生理的条件下的补体非依赖性抑制，使得大量抗原分子能与细胞结合。
