Genetically determined lack of CD45R- T cells in healthy individuals. Evidence for a regulatory polymorphism of CD45R antigen expression.

Abstract

The family of human leukocyte common antigens (LCA ; CD45) is composed of at least four glycoprotein members with molecular masses of 180, 190, 205, and 220 kD resulting from alternative splicing (1-4). On the protein level, the heterogeneity of different CD45 isoforms can be resolved by mAbs that react with restricted epitopes specific for distinct isoforms . In humans, mAb UCHLI detects the CD45RO epitope specific for the low molecular mass isoform (180 kD) of CD45 ; several mAbs detect the CD45R epitope present only on the high molecular mass isoform (205 and 220 kD) (5-7) .The CD45R and CD45RO isoforms have been reported to define complementary subsets among CD4+ and CD8+ T cells (8) that differ in functional properties . Whereas CD45RO' T cells respond well to recall antigens such as tetanus toxoid, weak or no reactivity has been reported for CD45R+ T cells (5, 9). After in vitro activation, CD45R + T cells have been shown to lose CD45R antigens and to express CD45RO molecules (10-12). These results led to the assumption that expression of the CD45RO isoform and loss of CD45R molecules are typical features of primed or memory T cells (13,14). We now report on a genetically determined variant pattern of CD45R expression . Volume 171 May 1990 1803-1808 Materials and Methods Brief Definitive ReportBlood Donors and Cell Separation . Heparinized peripheral venous blood was taken from 52 male and female healthy individuals ; furthermore, three families were studied. PBMC were isolated by Ficoll gradient centrifugation .mAbs and Flow Cytometry. The low molecular mass isoform of LCA (180 kD) was detected by mAb UCHLI (CD45RO) (5), donated by Dr. P. C. L. Beverley, London, UK. The high molecular mass isoform (205 and 220 kD) was identified by mAb Heidelberg, FRG) and by several antibodies included in the CD45R panel of the Fourth Workshop of Leucocyte Typing (6). Common epitopes expressed on all isoforms of LCA were identified by mAb GRT2 . Binding of the various mAbs to the respective CD45 epitopes was detected by indirect immunofluorescence. Coexpression of high and low molecular mass isoforms of CD45 was analyzed by two-color flow cytometry using directly labeled FITC-Leu-18 in combination with indirect staining for UCHLI . PBMC were incubated with mAb

The Exon A (C77G) Mutation Is a Common Cause of Abnormal CD45 Splicing in Humans

“…It has been previously reported that 8% of the individuals examined by flow cytometric analysis in the region of Hannover, Germany, exhibited the variant CD45RA expression pattern (15). Another study from Germany has shown a much lower frequency (Ͻ1%) (20).…”

“…Furthermore, no difference in susceptibility to HIV infection in vitro was shown between thymus samples with the normal and variant CD45 splicing (22). However, given the similarity between the defect of activation-induced CD45RA down-regulation in thymocytes (22) to that of the previously described lack of CD45RA down-regulation in peripheral T cells (15,16), we analyzed the association between abnormal CD45 splicing in the thymus and exon A (C77G) mutation. Our data clearly indicate that exon A (C77G) transversion is the cause FIGURE 2.…”

“…A genetically determined variant pattern of CD45 isoform expression has been recognized in humans (15). Activated or memory lymphocytes in these individuals continue to express both high and low molecular mass CD45 isoforms in contrast to the normal pattern of low molecular mass isoform expression.…”

77 C/G mutation in the tyrosine phosphatase CD45 gene and autoimmune hepatitis: evidence for a genetic link

“…11 The analysis of T cells revealed an aberrantly high expression level of the high molecular weight CD45 isoforms in some individuals. 12 Changes in CD45 expression may alter immune responses in those patients by affecting activation, adhesion and migration of immune cells. 13 This splice variant was found to be associated with a C-G transition at nucleotide position 77 of exon A in the CD45 gene, 14 and subsequently it was shown that an exonic splicing silencer is disrupted by the mutation.…”

Differential requirements for HIV-1 replication in naive and memory CD4 T cells from asymptomatic HIV-1 seropositive carriers and AIDS patients

“…only double-positive cells were observed (CD45RA'"*^/ CD29'"^*'); Ihus. CD4 T cells from this paiient were considered as memory or primed cells [11]. A second series of three control donors and three asymptomatic, previously unlreated patienis, all displaying > 400/mm' CD4 T cells, was studied lo better define the role of the different stimuli in supporting viral replication.…”