Phenotypic and functional immaturity of human umbilical cord blood T lymphocytes.

Abstract

Successful implementation of bone marrow transplantation for hematopoletic reconstitution is limited by the lack of suitably IELA-matched donors and by the occurrence of graft-versus-host disease that frequently accompanies this procedure. Recent clinical reports have implied that the use of umbilical cord blood as a source of transplantable stem cells may solve these problems. To date, definitive experiments have not been performed to assess the immunological potential of T cells found in umbilical cord blood, which could mediate graft-versus-host disease. In the present study we have observed that umbilical cord blood contains T lymphocytes that appear to be phenotypically immature. In addition, umbilical cord blood lymphocytes appeared to be functionally immature as shown by minimal responses to stimulation with interleukin 2, phytohemagglutinin, or alloantigens. Thus, umbilical cord blood may be more suitable for allogeneic transplantation than bone marrow in that these cord blood cells may not be as capable of mediating graft-versus-host disease.Bone marrow transplantation plays an integral part in the treatment of various cancers and inherited blood disorders. The ideal donor for bone marrow transplantation is an identical twin, the next best donor being an HLA-matched sibling. As 1 ± 2 8 ± 4 5 ± 5 7 ± 3 2 ± 2 10 + 5 4 ± 3 2 ± 3 5 ± 4 9 ± 5 3 ± 2 84 ± 6 PBL (n = 13) 62 + 11 38 ± 9 22 ± 6 63 ± 8 3 ± 3 11 ± 5 13 ± 8 8 ± 2 6 ± 5 14 ± 6 6 ± 3 17 ± 6 0 ± 0 0 ± 0 1 ± 0.4 53 ± 20 HUCB and PBL mononuclear cells were isolated and analyzed by flow cytometry. The mean percentage ofcells positive for each ofthe indicated antigens is shown, as well as the standard deviation for each population of cells. The data were derived from independent analysis of 50 HUCB and 13 PBL samples. Data were analyzed by t test, as reported in the text. TCR, T-cell antigen receptor.CD45RA phenotype. More importantly, JfUCB T cells expressed the CD3 antigen at lower levels than jlid PBL T cells (Fig. 1). The average mean fluorescence of d>3 expression on T cells of five randomly selected HUCB samples was 599 + 9.8 (mean ± SEM) versus 659 ± 6.7 for the CD3 expression of T cells from five randomly selected PBL samples.In addition, percentages of B cells (CD19+ and CD24+), monocytes (Macl+) and NK cells (CD16+) were comparable to those in PBL samples, but s50% of the B cells in cord blood were of the CD5+ phenotype, indicative of immature lymphocytes. Relatively few cells in HUCB expressed class II HLA antigens, and cells expressing the HLA-DP antigens were barely detectable. Those HUCB cells that did express class II HLA antigens did so at a level of expression that was at least an order of magnitude lower than that found on PBLs (as determined by the mean channel fluorescence) (data not shown). Functional Analysis of T Lymphocytes from HUCB. HUCB was analyzed immediately upon isolation for the ability ofthe cells to mediate cytolysis. No lytic activity was detectable in fresh HUCB cells, neither NK cell-like lysis (as measured a...

TNF-α-induced apoptosis in neonatal lymphocytes: TNFRp55 expression and downstream pathways of apoptosis

“…; 570 ± 15.7) T cells. This observation is in contrast to that of Harris et al 41 who reported decreased density of CD3 on cord blood T cells. However, these investigators did not provide data on background staining with isotype control.…”

“…18,31,32,41 Therefore, decreased TNFR-I expression in cord blood T cells could be due to a shift towards CD45RA + population. However, we observed no significant difference in the expression of TNFR-I in CD45RA + and CD45RO + subsets of CD4 + and CD45RA + subsets of CD8 + T cells between cord blood and peripheral blood.…”

“…cDNA was synthesized using 200 ng of total cellular RNA and 100 ng of random hexamers in a 20 l volume of a solution containing 50 mm tris HCl, 75 mm KCl, 3 mm MgCl 2 , 10 mm DTT, 500 m each of dNTPs and 10 U reverse transcriptase using a RT-PCR kit (Perkin-Elmer, Branchburg, CT, USA). For quantitation, graded amounts of cDNA were used and PCR was carried out as described 41 for 25 cycles. Sense and antisense primers for TNFR-I were purchased from Clontech (Palo Alto, CA, USA).…”

“…[16][17][18][19][20][21][22][23][24][25][26][27] Neonatal lymphocytes are functionally immature with regard to proliferative response to mitogens and antigens, cytokine production, antibody production, and other effector functions. Neonatal lymphocytes also demonstrate increased susceptibility to tolerance induction and to the immunosuppressive effects of cyclosporin A and glucocorticoids.…”

“…[28][29][30] Furthermore, the majority of neonatal T cells are naïve (CD45RA + ) phenotype. 18,31,32 It has been demonstrated that naïve T cells are less susceptible to apoptosis than memory (CD45RO + ) T cells. 33 Recently, age-related changes in T cell apoptosis have been reported.…”