MOLECULAR DEFINITION OF A POLYMORPHIC ANTIGEN (LA45) OF FREE HLA-A AND HLA-B HEAVY-CHAINS FOUND ON THE SURFACES OF ACTIVATED B-CELL AND T-CELL
MOLECULAR DEFINITION OF A POLYMORPHIC ANTIGEN (LA45) OF FREE HLA-A AND HLA-B HEAVY-CHAINS FOUND ON THE SURFACES OF ACTIVATED B-CELL AND T-CELL
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DOI：
10.1084/jem.174.5.1085
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发表时间：
1991-11-01
影响因子：
15.3
通讯作者：
PARHAM, P
中科院分区：
文献类型：
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作者：
MADRIGAL, JA;BELICH, MP;PARHAM, P
最近描述了一种与“人 T 淋巴细胞上新的激活诱导表面结构”（LA45 抗原）反应的单形单克隆抗体（LA45 抗体），该结构类似于游离的 I 类重链（Schnabl、E.、H. Stockinger、O. Majdic、H. Gaugitsch、I.J.D. Lindley、D. Maurer、A. Hajek-Rosenmayr 和 W. Knapp. 1990。医学 171:1431）。该抗体用于从 HUT 102 肿瘤细胞中克隆 I 类重链（LA45 基因），但矛盾的是，该细胞在转染至猴 COS 细胞后并未产生 LA45 抗原。我们在此显示 LA45 基因是 HLA-Aw66.2，这是 HLA-A 基因座的一个先前未表征的等位基因。之前确定的 LA45 序列与来自 HUT 102 的 HLA-Aw66.2 和源自与 HUT 102 相同个体的 CR-B B 细胞系的序列不同，通过在 α-1 结构域中的位置 4 处用色氨酸取代丝氨酸。将 HLA-Aw66.2 以及用丝氨酸 4 取代色氨酸的该基因突变体转染人 B 细胞系 (C1R) 均导致 LA45 表位的表达。此外，我们发现 LA45 表位在 Epstein Barr 病毒转化的 B 细胞系以及凝集素激活的 T 细胞上表达，但在长期 T 细胞系或未刺激的外周血 T 细胞上不表达。 LA45 抗体的特异性是多态性的，并且 LA45 表位的存在与 α-1 结构域螺旋的残基 62 和 63 处的精氨酸、天冬酰胺 (RN) 序列精确相关。 LA45 表位分布广泛，与 HLA-A 和 -B 基因座的一半等位基因相关，但与 HLA-C 基因座无关。所有结果都与某些细胞类型表面存在游离 HLA-A 和 HLA-B 重链库一致，但其他细胞类型则不然。此类分子可能与凝集素激活的 T 细胞的 HLA 相关 I 类同种抗原有关。我们假设游离重链是由 β-2-微球蛋白从空 HLA-A、B 分子或具有弱结合肽的分子亚群中解离产生的，其大小根据细胞激活和肽供应而变化。
A monomorphic monoclonal antibody (LA45 antibody) reactive with "a new activation-induced surface structure on human T lymphocytes" (LA45 antigen) that resembled free class I heavy chains has recently been described (Schnabl, E., H. Stockinger, O. Majdic, H. Gaugitsch, I.J.D. Lindley, D. Maurer, A. Hajek-Rosenmayr, and W. Knapp. 1990. J. Exp. Med. 171:1431). This antibody was used to clone a class I-like heavy chain (LA45 gene) from the HUT 102 tumor cell, which paradoxically did not give rise to the LA45 antigen on transfection into monkey COS cells. We show here that the LA45 gene is HLA-Aw66.2, a previously uncharacterized allele of the HLA-A locus. The previously determined LA45 sequence differs from that of HLA-Aw66.2, from HUT 102, and the CR-B B cell line derived from the same individual as HUT 102 by substitution of tryptophan for serine at position 4 in the alpha-1 domain. Transfection of HLA-Aw66.2, and of a mutant of this gene with serine 4 substituted for tryptophan, into a human B cell line (C1R) both resulted in expression of the LA45 epitope. Furthermore, we find expression of the LA45 epitope on Epstein Barr virus-transformed B cell lines as well as lectin-activated T cells, but not on long-term T cell lines or unstimulated peripheral blood T cells. The specificity of the LA45 antibody is polymorphic and the presence of the LA45 epitope is precisely correlated with the sequence arginine, asparagine (RN) at residues 62 and 63 of the helix of the alpha-1 domain. The LA45 epitope is broadly distributed, being associated with half the alleles of both HLA-A and -B loci but none of the HLA-C locus. All the results are consistent with the presence of pools of free HLA-A and -B heavy chains at the surfaces of certain cell types but not others Such molecules are probably responsible for the HLA-associated class I alloantigens of lectin-activated T cells. We hypothesize the free heavy chains result from dissociation of beta-2-microglobulin from subpopulations of empty HLA-A,B molecules, or molecules with weakly bound peptides, that vary in size depending on cellular activation and peptide supply.