D'Arena G, Musto P, Cascavilla N, Di Giorgio G, Fusilli S, Zendoli F, Carotenuto M
Division of Hematology, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy.
Haematologica. 1998 Mar;83(3):197-203.
One of the most important potential advantages in the use of human umbilical cord blood (HUCB) for hematopoietic reconstitution after myeloablative therapy seems to be the lower occurrence of acute graft-versus-host-disease (GvHD) in recipients after allogeneic transplantation. Since mature T cells play an important role in GvHD pathogenesis, we tried to verify whether a different immunophenotypic pattern exists between HUCB and peripheral blood (PB) T cells.
An immunophenotypic study on 40 HUCB and 40 PB samples from healthy adult volunteers was performed, by means of flow cytometry using a large panel of monoclonal antibodies in double labeling.
The absolute lymphocyte count was greater in HUCB (5233 +/- 1808 microL) than in adult PB (1941 +/- 378 microL). Significant differences in percentage were found between cord and adult T-cells, respectively (CD3+: 59.9 +/- 12 vs 74.9 +/- 4.6%), CD3- CD16+ and/or CD56+ natural killer (NK) cells (23.8 +/- 10.1 vs 10.8 +/- 5.3%) and CD3+CD16+ and/or CD56+ cytotoxic T lymphocyte subset (0.3 +/- 0.3 vs 10.7 +/- 4.1%). There was no difference in CD4/CD8 ratio (1.7 +/- 0.5 vs 1.6 +/- 0.2%) between the two groups. In absolute terms, HUCB contained an higher number of all lymphocyte subsets, with the exception of CD3+CD16+ and/or CD56+ T lymphocyte subpopulation, CD3+CD25+ and CD3+HLADR+ activated T-cells. CD38, a marker of activation and immaturity, was present on virtually all cord T cells and on approximately half of the adult T cells. The large majority of HUCB T cells co-expressed CD45RA naive antigen (CD4+CD45RA+: 87.6 +/- 5.2%, CD8+ CD45RA+: 93.5 +/- 7.8%; CD4+CD45RO+: 12.3 +/- 5.2%; CD8+CD45RO+: 6.4 +/- 7.8%) whereas in adult PB T cells an higher number of CD45RO+ memory cells was detected (CD4+CD45RA+: 44.8 +/- 9.6%; CD8+CD45RA: 71.5% +/- 8.1%; CD4+CD45RO+: 55.2 +/- 9.6%; CD8+ CD45RO+: 28.5 +/- 8.1%). Finally, less than 14% of lymphocytes were shown to belong to B lineage in both sources, while, in absolute terms, they were more represented in HUCB with respect to adult PB.
In the present study we found significant difference between HUCB and adult PB lymphocytes in their immunophenotypic profile. In particular HUCB showed T lymphocytes that appeared to be phenotypically immature. Indeed, as a likely consequence of poor antigenic experience during pregnancy, the majority of HUCB cells were naive, expressing the RA isoform of the CD45 molecule. These findings could justify the previously reported reduced cord blood lymphocyte alloreactivity when allogeneic transplantation is performed and require further functional studies in order to confirm the impairment of HUCB immune system response to alloantigens.
在清髓性治疗后使用人类脐带血（HUCB）进行造血重建的最重要潜在优势之一，似乎是同种异体移植后受者急性移植物抗宿主病（GvHD）的发生率较低。由于成熟T细胞在GvHD发病机制中起重要作用，我们试图验证HUCB和外周血（PB）T细胞之间是否存在不同的免疫表型模式。
采用大量单克隆抗体进行双标记流式细胞术，对40份来自健康成年志愿者的HUCB样本和40份PB样本进行免疫表型研究。
HUCB中的绝对淋巴细胞计数（5233±1808μL）高于成年PB（1941±378μL）。脐带血和成人T细胞在百分比上存在显著差异，分别为CD3 +：59.9±12对74.9±4.6%，CD3 - CD16 +和/或CD56 +自然杀伤（NK）细胞（23.8±10.1对10.8±5.3%）以及CD3 + CD16 +和/或CD56 +细胞毒性T淋巴细胞亚群（0.3±0.3对10.7±4.1%）。两组之间的CD4/CD8比值无差异（1.7±0.5对1.6±0.2%）。就绝对值而言，HUCB包含更多数量的所有淋巴细胞亚群，但CD3 + CD16 +和/或CD56 + T淋巴细胞亚群、CD3 + CD25 +和CD3 + HLA - DR +活化T细胞除外。CD38是活化和不成熟的标志物，几乎所有脐带血T细胞和大约一半的成人T细胞都有表达。大多数HUCB T细胞共表达CD45RA幼稚抗原（CD4 + CD45RA +：87.6±5.2%，CD8 + CD45RA +：93.5±7.8%；CD4 + CD45RO +：12.3±5.2%；CD8 + CD45RO +：6.4±7.8%），而在成人PB T细胞中检测到更多数量的CD45RO +记忆细胞（CD4 + CD45RA +：44.8±9.6%；CD8 + CD45RA：71.5%±8.1%；CD4 + CD45RO +：55.2±9.6%；CD8 + CD45RO +：28.5±8.1%）。最后，两种来源中均显示不到14%的淋巴细胞属于B谱系，而就绝对值而言，HUCB中的B淋巴细胞比成人PB中更多。
在本研究中，我们发现HUCB和成人PB淋巴细胞在免疫表型特征上存在显著差异。特别是HUCB显示出表型上不成熟的T淋巴细胞。实际上，作为孕期抗原接触不足的可能结果，大多数HUCB细胞是幼稚的，表达CD45分子的RA异构体。这些发现可以解释先前报道的进行同种异体移植时脐带血淋巴细胞同种异体反应性降低的现象，并且需要进一步的功能研究以证实HUCB免疫系统对同种异体抗原反应的损害。
