Disease relevance of CD7

• CD7-restricted activation of Fas-mediated apoptosis: a novel therapeutic approach for acute T-cell leukemia [1].
• However, CD7 on NK cells did not seem to transduce a lytic signal, because it neither mediated redirected killing of Fc gamma R+ murine mastocytoma P815 cells nor triggered lysis of a hybridoma expressing the antibody in a membrane-bound form [2].
• CD7 and CD43 colocalized in small patches away from the membrane blebs, which excluded externalized phosphatidylserine [3].
• Finally, comparison of the CD7 transmembrane sequence with CD4 and HIV transmembrane sequences and with respiratory syncytial virus fusion sequences demonstrated similar sequence motifs among these molecules [4].
• The high expression of CD5 and CD7 antigen in pancreatic ductal carcinoma and cholangiocarcinoma and high expression of CD7 in epithelioid sarcoma may have diagnostic value [5].

High impact information on CD7

• Targeting pokeweed antiviral protein to CD4+ T cells by conjugating it to monoclonal antibodies reactive with CD5, CD7 or CD4 expressed on CD4+ cells, increased its anti-HIV potency up to 1,000-fold [6].
• Crosslinking of the T cell-specific accessory molecules CD7 and CD28 modulates T cell adhesion [7].
• CD7 is preferentially expressed on naive T cells and is unique in being a potent inducer of naive T cell adhesion [7].
• Detailed immunological analysis demonstrated that the vast majority of these cells expressed T cell-associated antigens (i.e., CD7, CD5, CD2, CD4, and to a lesser extent, CD8) [8].
• Two-color flow cytometry revealed that among the IBM-MNCs the DCC protein was clearly expressed on the CD14+, CD13+, and factor 8+ cells, whereas it was low on the CD19+ and CD7+ cells and did not express on the CD34+, CD8+, and the glycophorin A+ cells [9].

Chemical compound and disease context of CD7

• A T cell surface membrane-associated glycoprotein, Tp40 (40,000 mol wt), also designated as CD-7, was not expressed by the T cells of a patient with severe combined immunodeficiency [10].
• The antibody was subcloned as a single chain Fv (scFv) fragment and genetically linked to a truncated Pseudomonas exotoxin A fragment containing the catalytic domains II and III but lacking the receptor binding domain I. Domain I was replaced by the scFv, thus conferring restricted specificity for CD7-positive cells [11].
• Both CD62L and CD7 in paraffin-embedded, formalin-fixed tissue are useful diagnostic adjuncts, especially in regard to the discrimination of lymphomatoid hypersensitivity reactions from true endogenous T-cell dyscrasia [12].
• Variables influencing CR rate were FAB subtype, CD7 positivity, chemotherapy regimen, creatinine level, hepatomegaly, and period of diagnosis [13].
• CD7 positive acute lymphoblastic leukemia successfully treated with high dose cytosine arabinoside and mitoxantrone: a case report [14].

Biological context of CD7

• A group of ALL cells whose cell surface phenotype was CD2 (SRBC receptor) negative and CD7 (T cell antigen) positive has been considered as precursor thymocyte ALL (pre-T-ALL) [15].
• In this study, we have studied the signals required for CD7 up-regulation on human T cells [16].
• The CD7 gp40 molecule is a member of the Ig gene superfamily and is expressed on T cell precursors before their entry into the thymus during fetal development [4].
• Using computer analysis, we transposed the amino acid sequence of the CD7 Ig kappa-like N-terminal domain of CD7 onto the spatial coordinates of REI, a previously reported Ig kappa-molecule highly homologous (48%) to the CD7 N-terminal Ig-like region [4].
• Neither 1.6 nM PMA, nor immobilized anti-CD5 mAb were mitogenic as a sole stimulus. mAb identifying CD4, CD7, CD11a, CD18, and major histocompatibility complex class I molecules were not comitogenic with PMA [17].

Anatomical context of CD7

• Few CD34+ cells in BM (2.7%) or PB (7%) expressed the T-cell antigen CD7 [18].
• p53 and N-ras mutations in two new leukemia cell lines established from a patient with multilineage CD7-positive acute leukemia [19].
• Two new myeloid cell lines (K051 and K052) were established from a patient with multilineage CD7-positive acute leukemia [19].
• Among 192 patients (26%) with T lineage ALL, 47 (6%; 24% of T lineage ALL) had lymphoblasts without sheep erythrocyte rosette formation, but with pan-T antigen CD7 on the membrane and intracellular CD3 proteins mostly in perinuclear accumulation [20].
• The CD7 Ag is also expressed on human NK cells, but its function has not been determined [2].

Associations of CD7 with chemical compounds

• Induction of T cell CD7 gene transcription by nonmitogenic ionomycin-induced transmembrane calcium flux [16].
• CD7 up-regulation by ionomycin was transient (24 to 72 h) and inhibitable by cyclosporin A, whereas CD7 up-regulation by PHA was sustained over 5 to 7 days and was significantly less inhibitable by cyclosporin A [16].
• However, in the presence of 20 mM ammonium chloride, IT directed against CD3, CD5, and CD7 were highly cytotoxic [21].
• The CD7 molecule appears to play a regulatory role in T cell proliferation, and the LFA-1 integrin molecule is involved in a wide range of immunologically important cell-cell interactions, as well as HIV-induced syncytium formation [22].
• The human CD7 antigen (gp40) is a cell surface glycoprotein found on thymocytes and mature T-cells [23].

Regulatory relationships of CD7

• The CD7 Ag was found to be expressed at a significantly (p < 0.002) higher level on fresh NK cells than on IL-2-activated, NK cells [2].
• One of them did not express the CD7 antigen but did express the CD33 antigen on the cell surface, suggesting that CD3-gamma transcription may not always be an event restricted to cells differentiating along the T-cell lineage [24].
• Discordant expression of myeloid antigens and myeloperoxidase in a case of t(8;21) positive AML expressing CD7 [25].
• The most interesting results were in the CALLA- group where 94% of the samples expressed the B cell antigen CD19 but 27% co-expressed CD7 [26].
• This demonstrates a novel function for CD7 as a death trigger and identifies galectin-1/CD7 as a new biologic death signaling pair [27].

Other interactions of CD7

• The 14 M2 AML cases lacking the t(8;21) commonly expressed CD2 (n = 5) or CD7 (n = 8) [28].
• This indicates that CB either contains very low numbers of these progenitors or that the antigen density of CD7 and CD19 on CD34+ cells is below the detection limit of the flow cytometer [29].
• Input HSCs were differentiated into T cells as evidenced by the expression of T-cell markers, such as CD7, CD1a, CD4, CD8, and CD3, and by detection of TCR excision circles [30].
• The absence of antigen expression by epidermal but not dermal T cells, which the authors have termed antigen discordance, was most prevalent for CD5, CD7, and TCR-beta, each being discordant in 6% to 7% of MF cases or patients tested [31].
• The vast majority of intestinal HSCs coexpressed the T cell Ag, CD7 (92% in the epithelium, 80% in the lamina propria) whereas <10% coexpressed the myeloid Ag CD33, suggesting that gut HSCs are a relatively mature population committed to the lymphoid lineage [32].

Analytical, diagnostic and therapeutic context of CD7

• Polyclonal anti-CD7 sera were studied using indirect immunofluorescence, RIA, radioimmunoprecipitation, and Western blot assays [4].
• The T ALL cells were rather mature by morphology and immunophenotyping, expressing CD7, CD4, CD8 and CD3 surface antigens and nuclear TdT [33].
• Finally, the complete remission (CR) rate, survival and event-free survival were analyzed according to the presence of lymphoid markers and also of some specific antigens such as CD7 and CD34 [34].
• Two-colour immunofluorescence and flow cytometry demonstrated co-expression of the antigen defined by F101.01 and the pan-T cell antigens defined by CD2, CD3, CD5, and CD7 antibodies [35].
• Sequence analysis revealed that the CD7 gene comprises four exons that span 3.5 kilobases [36].

References