McFarland H I, Nahill S R, Maciaszek J W, Welsh R M
Department of Pathology, University of Massachusetts Medical Center, Worcester 01655.
J Immunol. 1992 Aug 15;149(4):1326-33.
We have found that CD11b, a cell surface integrin of macrophages, granulocytes, and NK cells, is expressed by a subset of CD8+ T cells that include both the active virus-specific CTL and the virus-specific memory CTL populations. CD8+CD11b+ cells comprise less than 3% of naive mouse splenocytes, but after lymphocytic choriomeningitis virus (LCMV) infection increase by 9- to 12-fold by the peak (day 8) of the virus-specific CTL response. Depletion of day-8 splenocytes with anti-Mac-1 and C' or enrichment by sorting for CD11b+ or CD8+CD11b+ spleen cells demonstrated that LCMV-specific CTL are CD11b+. The CD11b+ subpopulation also contained the bulk of the IL-2-responsive CD8+ cells. MEL-14, a homing marker down-regulated on activated T cells, was down-regulated on the majority of CD8+ cells that became CD11b+. Less than 1% of LCMV-immune splenic lymphocytes expressed CD11b. Antibody and C' depletion of this population severely impaired the ability of immune splenocytes to respond to in vitro secondary stimulation with LCMV-infected peritoneal macrophages, but did not affect the generation of a primary allospecific CTL response in MLC. Mixing of CD8-depleted and CD11b-depleted LCMV-immune splenocytes failed to restore the ability of these cells to mount a virus-specific memory CTL response, indicating that a cell coexpressing CD8 and CD11b is essential for this response. As determined by limiting dilution analysis, the precursors for the LCMV-specific memory CTL response were enriched in the CD11b+ population of LCMV-immune splenocytes. CD11b stained far fewer CD8+ splenocytes from naive mice than did CD44 (Pgp-1), and among immune splenocytes it identified a small subpopulation of CD44hi cells, indicating that CD11b may be the best single marker available for discriminating between naive and memory CD8+ T cells.
我们发现，CD11b是巨噬细胞、粒细胞和自然杀伤细胞的一种细胞表面整合素，在包括活性病毒特异性细胞毒性T淋巴细胞（CTL）和病毒特异性记忆CTL群体的CD8⁺ T细胞亚群中表达。CD8⁺CD11b⁺细胞在未接触抗原的小鼠脾细胞中所占比例不到3%，但在淋巴细胞性脉络丛脑膜炎病毒（LCMV）感染后，在病毒特异性CTL反应的高峰期（第8天）增加9至12倍。用抗Mac-1和补体（C'）清除第8天的脾细胞，或通过分选CD11b⁺或CD8⁺CD11b⁺脾细胞进行富集，结果表明LCMV特异性CTL是CD11b⁺。CD11b⁺亚群还包含大部分对白细胞介素-2有反应的CD8⁺细胞。MEL-14是一种在活化T细胞上下调的归巢标志物，在大多数变成CD11b⁺的CD8⁺细胞上也下调。不到1%的LCMV免疫脾淋巴细胞表达CD11b。用抗体和补体清除该群体严重损害了免疫脾细胞对LCMV感染的腹腔巨噬细胞进行体外二次刺激的反应能力，但不影响混合淋巴细胞培养（MLC）中初次同种异体特异性CTL反应的产生。将去除CD8和去除CD11b的LCMV免疫脾细胞混合，无法恢复这些细胞产生病毒特异性记忆CTL反应的能力，这表明共表达CD8和CD11b的细胞对该反应至关重要。通过有限稀释分析确定，LCMV特异性记忆CTL反应的前体细胞在LCMV免疫脾细胞的CD11b⁺群体中富集。与CD44（Pgp-1）相比，CD11b染色的未接触抗原小鼠的CD8⁺脾细胞要少得多，并且在免疫脾细胞中，它识别出一小部分CD44高表达细胞，这表明CD11b可能是区分未接触抗原和记忆性CD8⁺ T细胞的最佳单一标志物。
