Fluctuations in T helper subpopulations in relapsing-remitting multiple sclerosis

Patients with active multiple sclerosis (MS) have been reported to have a depletion of CD4+ CD45R+ cells, the immature resting CD4+ subpopulation. Using Leu 3a(anti-CD4) and Leu 18(anti-CD45R), the frequencies and absolute numbers of CD4+ CD45R+ and CD4+ CD45R- subsets were measured in 30 patients with MS and 17 healthy controls. These subsets were monitored every 6 weeks over a 6 month period. CD4+ CD45R- cells were found to be increased in relapse compared to remission (p less than 0.005) while CD4+ CD45R+ levels were not significantly altered in relapse. However, the CD4+ subset ratio (CD4+ CD45R-/CD4+ CD45R+) was significantly higher in relapse compared with remission (p less than 0.002). Furthermore, these findings were upheld when data from the same 6 patients in relapse and remission was compared. Increased disease activity was not associated with changes in any of the other parameters measured (total T cells, total CD4+ cells, suppressor cells or activated T cells). These results suggest that relapse in MS is accompanied by the conversion of CD4+ CD45R+ resting cells to CD4+ CD45R- primed cells.     

Decrease in memory (CDw29-high) cerebrospinal fluid cells from acute MS patients

The CD45R (2H4) and CDw29 (4B4) molecules are probably involved in the regulation of immunological memory: CD45R functionally defines naive or virgin cells (prior to activation by exposure to antigen), while CDw29 characterizes previously activated (memory) cells. By means of two-colour fluorescence analysis, we studied CD4 and CD8, CD45R and CD4 and CD8 CDw29 cells from the cerebrospinal fluid (CSF) of 27 acute (MSa), and 10 stable (MSs) multiple sclerosis (MS) patients. We also compared 17 patients affected with various non-inflammatory (OND) diseases of the central nervous system (CNS). The most striking finding was the increased percentage of CD4+CD29-, CD4+CD45R- and CD8+CD45R- cells and the decreased percentage of CD4-CDw29+ and CD8- CDw29+ subsets in MSa patients compared to OND and MSs populations. These data suggest a decrease in memory cells (CDw29+) during the acute phase of MS. The modulation of CDw29 receptor could play a role in the genesis of acute MS attacks.     

Natural killer cells and lymphocyte subsets in active MS and acute inflammation of the CNS

Cerebrospinal fluid (CSF) and peripheral blood (PB) lymphocyte subsets were determined by flow cytometry (FCM) in 15 patients with active multiple sclerosis (MS) and 15 patients with acute inflammatory diseases (ID) of the central nervous system (CNS) in order to establish correlations between the two groups of diseases, as well as between the CSF and PB subsets distribution. A panel of monoclonal antibodies was applied to all the samples: Leu3 (CD4), Leu4 (CD3), Leu2 (CD8), Anti-HLA-DR, Leu11 (CD16). Statistical analysis did not show differences in CD3+ nor in CD3+ DR+ T-cells both in the CSF and PB in the two groups of patients. CD4+ cells were significantly higher in the CSF than in the PB, while CD8+, DR+ CD3- and CD16+ cells were constantly lower in the CSF without differences between the two groups of diseases.     

Fluctuations of CD4+ T-cell subsets in remitting-relapsing multiple sclerosis

Patients with multiple sclerosis (MS) frequently have selective depletion of the CD45R+CD4+ T-cell subset during active phases of disease. To study the relationship between changes in this subset and the onset of objective clinical exacerbations of disease, a longitudinal study was undertaken. Two CD4+ T-cell subsets and two CD8+ T-cell subsets were monitored by two-color immunofluorescence using a fluorescence-activated cell sorter. These subsets of peripheral blood lymphocytes were monitored monthly for one year in a group of 9 patients with remitting-relapsing MS and in 11 healthy age-matched control subjects. Significant changes in the ratio of two CD4+ T-cell subsets (CD45R-/CD45R+) were detected in 7 of 9 patients with MS, but not in any of the control subjects. Of those 7 persons, 4 suffered major clinical relapses substantiated by alterations in the neurological examination. The other 3 suffered minor relapses with subjective clinical abnormalities. All 7 had increased CD4+ T-cell subset ratios (%CD4+CD45R-/%CD4+CD45R+) within the month that new symptoms were reported. Most such increases resulted from a simultaneous depletion in the number of CD45R+CD4+ T cells and an increase in the number of CD45R-CD4+ T cells. One patient suffered a major relapse with no change in the ratio of CD4+ subsets but had a depletion of all CD4+ T cells. There were no consistent changes in any of the other subsets measured. These results indicate that a subgroup of patients with MS have abnormal fluctuations of two CD4+ T-cell subsets, which may correlate with increased disease activity.     

Differences in systemic and central nervous system cellular immunity relevant to relapsing–remitting multiple sclerosis

In order to elucidate the differences between systemic and central nervous system (CNS) immunity that are relevant to exacerbations of multiple sclerosis (MS), paired peripheral blood and cerebrospinal fluid (CSF) samples obtained from 36 non-treated patients with relapsing-remitting MS (RRMS) were simultaneously examined using flow cytometry to determine the percentages of functional lymphocyte subsets, as well as enzyme-linked immunosorbent assays for measuring soluble immune mediators.Active RRMS patients (n = 27) were characterized by an increase in CD4+ CXCR3+ Th1 cells in blood as compared with inactive patients (n = 9), and this parameter was inversely correlated with plasma levels of IL-10 and IL- 12p70. In contrast, an increase in the percentage of CD4+ CD25+ cells and a decrease in the percentage of CD8+ CD11a(high) cells were features of CSF samples from those with active RRMS. Further, CSF CD4+ CD25+ cells had a close association with leukocyte counts as well as albumin and CXCL10 levels in the CSF, and, thus, could be useful as a measure for inflammatory reactions in the CNS. On the other hand, CD8+ CD11a(high) cells may function as immunoregulatory cells, as their percentage in the CSF showed a positive correlation with CSF levels of the anti-inflammatory cytokine IL-4. These findings suggest that MS relapses occur in a combination with altered cell-mediated immunity that differs between the peripheral blood and CSF compartments, while measurement of lymphocyte subsets may be helpful for monitoring disease status.     

CD4+ lymphocyte subsets in the cerebrospinal fluid of multiple sclerosis and non-inflammatory neurological diseases

Summary We studied paired cerebrospinal fluid (CSF) and peripheral blood (PB) samples from 18 inactive multiple sclerosis (MS) patients and 10 with non-inflammatory neurological diseases. By means of a dual-colour cytofluorimetric micromethod we were able to count 1500 cells on average in each CSF sample. We found a significant reduction of CD45RA+ and CD4+CD45RA+ cells in the CSF of MS patients. Similarly, CD45RA+ and CD4+CD45RA+ CSF/PB ratios were lower compared with controls. The reduction of suppressor-inducer T-cells did not correlate with CD8+ cell levels in the CSF. The CD4+ subset ratio (CD4+CD45RA–/CD4+CD45RA+) was significantly increased in the CSF of MS patients. Our data suggest that the reduction of CD4+CD45RA+ cells in the PB is not due to a segregation of such cells in the CSF. Conversely, CSF changes reflect changes in the PB similar to these found for other T-cell subsets.     

Increased numbers of mononuclear cells from blood and CSF expressing interferon-gamma mRNA in multiple sclerosis are from both the CD4+ and the CD8+ subsets

Activated, cytokine-producing lymphocytes may regulate central nervous system (CNS) inflammation in multiple sclerosis (MS). We utilize a novel combination of in situ hybridization (ISH) and immunocytochemical staining of peripheral blood lymphocytes (PBLs) to identify spontaneously interferon-gamma (IFNgamma) mRNA expressing cells as CD4+ or CD8+. A major proportion of the IFNgamma mRNA expressing lymphocytes belonged to the CD4+ lineage, which concords with the cellular composition of MS brain lesions, findings in experimental models and the HLA class II haplotype association in MS. There were also significantly more CD8+ IFNgamma mRNA expressing lymphocytes in the MS patients compared with healthy controls, further suggesting the contribution of activated cells from this lineage in the inflammatory response in MS. Both CD4+ and CD8+ IFNgamma mRNA expressing cells were enriched in the cerebrospinal fluid (CSF) as compared with the peripheral blood of the MS patients. Combined with emerging genetic data on HLA class I influences, our data argues for a joint role of activated CD8+ and CD4+ cells in the pathogenesis of MS.     

Elevated cerebrospinal fluid CD4/CD8 T cell ratio in myasthenia gravis

The proportions of CD2+, CD4+ and CD8+ lymphocytes were determined with the 3-layer indirect immunoperoxidase technique in the cerebrospinal fluid (CSF) of 31 patients with myasthenia gravis (MG) and 21 control subjects without autoimmune or central nervous system (CNS) diseases. None of the MG patients were using immunosuppressive drugs and all were thymectomized shortly after CSF sampling. Analysis of the reference population showed that the percentage of CD4+ lymphocytes and accordingly the CD4+/CD8+ T cell ratio is normally higher in CSF than in peripheral blood (PB). Compared to the controls, the mean percentage of CD4+ lymphocytes and the mean CD4+/CD8+ ratio in CSF were significantly higher in MG patients. In addition, the CD4+/CD8+ ratio was elevated in the CSF of 15 MG patients (48%) as a result of an elevation in the proportion of CD4+ and/or a decrease in CD8+ T cells. Among MG subjects the mean proportion of CD4+ lymphocytes was higher in the CSF of patients with also an elevated number of enlarged stimulated lymphoid cells in their CSF, which implies that these lymphocytes are often of the CD4+ phenotype. The percentage of CD4+ T cells in CSF was significantly higher in MG patients with a hyperplastic thymus or a thymoma than in those with an involuted thymus. Neither in MG patients nor in the reference population could an association be observed between CSF and PB lymphocyte subsets. In the controls this suggests that immunologic events of the CNS are normally not directly reflected in PB.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immune system-associated antigens on the surface of peripheral blood lymphocytes in patients with Alzheimer's disease.

We investigated the immune-associated antigens of peripheral lymphocytes from 13 patients with Alzheimer's disease (AD) and 13 age-matched healthy control subjects using two-color analysis with flow cytometry. Four ratios of immune-related antigens, T/B lymphocytes, CD4/CD8, CD4/CD45R and CD4/HLA-DR, were compared for the AD and control groups. The T/B and CD4/CD8 ratios did not differ between the groups, the ratio of CD4+CD45R+ subset in the AD group was lower than the ratio in the control group, and the ratios of CD4+ CD45R- and CD4+HLA-DR+ subsets in the AD group were significantly higher. Further, in the AD group, the CD4+ CD45R+/CD4+ ratio was lower and the CD4+ CD45R- CD4+ ratio was higher than in the control group.     

Flow cytometric analysis of lymphocytes in cerebrospinal fluid in patients with tick-borne encephalitis

Introduction – Cerebrospinal fluid (CSF) lymphocyte subsets were examined by flow cytometry in 33 patients with tick-borne encephalitis (TBE) in order to determine their values. Patients and methods – Lymphocytes were isolated from CSF and lymphocyte subsets were determined: lymphocytes T (CD3+), lymphocytes B (CD19+), NK cells (CD3-CD56+), helper T cells (CD3+CD4+) and cytotoxic T cells (CD3+CD8+). The expression of IL-2 receptors (CD25+) and transferrin receptors (CD71+) on T cells and HLA-DR molecules on T cell subsets was examined. Furthermore, possible relationships among different TBE patient population variables (gender, age, severity of disease, duration of meningitis) were considered. Results – The analyses of the CSF lymphocyte population subsets are presented. Lymphocytes T (CD3+) were significantly higher in the CSF than in the peripheral blood as was the case with the T cells that expressed transferrin receptors (CD71). Lymphocytes B (CD19+) and NK cells (CD3-CD56+) prevailed in the peripheral blood. In the early course of the disease, a higher expression of HLA-DR molecules on T lymphocytes was observed, while later a higher expression of IL-2 receptors (CD25+) was observed. Discussion – Significant differences in lymphocyte subsets between the CSF and the peripheral blood were found. Significant time-dependent changes of CSF lymphocyte subsets during course of infection were observed. The results of the present study give us deeper insight into CNS cellular immunopathogenic mechanisms in patients with TBE.     

Lymphocyte subset numbers in cerebrospinal fluid: comparison of tick-borne encephalitis and neuroborreliosis

OBJECTIVE: The aim of this study was to analyze lymphocyte subset numbers in cerebrospinal fluid (CSF) from patients with tick-borne encephalitis (TBE) and acute neuroborreliosis. METHODS: CSF lymphocyte subsets were enumerated in 42 TBE and nine neuroborreliosis patients using flow cytometry. RESULTS: The CSF numbers of CD4+, CD8+, HLA-DR+ and total-T lymphocytes, B lymphocytes, and NK cells were all greater in neuroborreliosis patients than in TBE patients. Neuroborreliosis patients showed positive correlation of CSF protein levels with the numbers of CD4+, HLA-DR+ and total-T lymphocytes. Also, the numbers of CSF B lymphocytes correlated positively with intrathecal Borrelia burgdorferi-specific IgG antibodies. Conversely, TBE patients demonstrated intrathecal protein levels that correlated positively with all investigated CSF lymphocyte subsets. CONCLUSION: These results suggest an intensive recruitment of lymphocyte subsets into the central nervous system (CNS) during acute neuroborreliosis, whereas TBE is characterized by a lower accumulation of lymphocyte subsets in the CSF.     

CSF lymphocyte subsets in aseptic meningitis: dual-labelling analysis with flow cytometry

In order to characterize the CSF (cerebrospinal fluid) lymphocytes in CNS (central nervous system) inflammation, we examined paired samples of CSF and PB (peripheral blood) of 19 patients with acute aseptic meningitis, performing the dual labelling method on flow cytometry. Significantly higher percentages of CD3+ (T cell), CD4+ (helper-inducer), Leu3a+ Leu15- (cytotoxic-T) and HLA-DR+ CD3+ (activated-T) cells were identified in the CSF than in the PB of these patients. We observed significantly lower percentages of CD19+ (B cell), Leu2a+ Leu18+ (suppressor-inducer) and HLA-DR+ CD3- cells in the CSF than in the PB of these patients. Relative increases in helper-inducer, cytotoxic-T and activated-T cells in the CSF of aseptic meningitis are supposed to represent an active inflammatory process. However, whether these changes are specific or pathognomonic to any disease(s) remains to be solved.     

Analysis of effector CD4 (OX-40+) and CD8 (CD45RA+CD27-) T lymphocytes in active multiple sclerosis

OBJECTIVE: Recently, effector T-cell subpopulations have been identified that can be distinguished by expression of members of the TNF-R family: CD4+OX-40+ cells are CD4 helper-effector cells CD8+CD45RA+CD27 cells are CD8-killer-effector cells. We investigated whether these lymphocyte subsets were increased in the active phase of multiple sclerosis (MS). MATERIAL AND METHODS: Multiple colour immunofluorescence staining was performed on peripheral blood lymphocytes of 28 patients with active MS and of 29 healthy controls, followed by FACS analysis. RESULTS: Frequencies of CD8-killer-effector cells showed a wide interindividual range in both groups and percentages of CD4 helper-effector cells were low. No significant difference between the groups was observed for these subsets, but CD8+CD45RA-CD27 were increased in MS. In healthy individuals, CD4 helper-effector cells correlated with the total percentages of memory cells. Moreover, CD4+ and CD8 memory cells were strongly correlated. CONCLUSION: The here described recently identified effector CD4 and CD8 lymphocyte subpopulations were not increased in clinically active MS. It is however still possible that in MS, myelin-specific encephalitogenic cells reside within these subsets.     

T-cell subsets in the cerebrospinal fluid and peripheral blood of multiple sclerosis patients treated with high-dose intravenous methylprednisolne

To determine the effects of high-dose intravenous methylprednisolone (MP) on lymphocytes and lymphocyte subpopulations in the cerebrospinal fluid (CSF) and peripheral blood (PB) in multiple sclerosis (MS) patients, we studied 67 patients with definite MS treated with MP. They were classified according to the disease course: 32 chronic progressive (CP) patients, 25 relapsing-remitting (RR) patients, and 10 patients with a chronic progressive disease course accompanied by relapses and remissions (CP + RR). MS patients were treated with 1000 mgr intravenous MP daily for 10 consecutive days. Before and after MP treatment we simultaneously studied CSF and PB CD3 +, CD4 +, CD8 +, CD20 +, and Ial + cells subsets. Kurtzke's Expanded Disability Status Scale (EDSS) was used for clinical evaluation. Progression rate was defined as the ratio of EDSS to disease duration. Thirteen patients with lumbar disk herniation were investigated as controls. Before MP, we found in MS patients, especially in the CP group, significantly lower CD4 + T-cell percentages in the PB with respect to controls (P<0.05). The percentage of CD4 + T-cells in the CSF of MS patients was significantly higher compared with PB (p = 0.0001), and tended to be higher than in controls (p = 0.072). The CSF mononuclear cell counts were significantly correlated with higher percentages of CSF CD3 + (r = 0.40) and CD4 + (r = 0.47) T-cells and lower CSF CD8 + (r = -0.33) T-cell percentages. B-cell percentages in the CSF were significantly elevated compared with controls for all MS groups. No relation could be obtained between T- or B-cell subsets and EDSS or progression rate. After MP, a significant decrease in PB CD8 + T-cell percentage and simultaneously an increase of the percentage CD8 + T-cells in CSF was noted in the entire MS group and in the CP and RR MS patients. Except for the CP + RR MS patients, CD4 + T-cell percentages in the PB or CSF showed insignificant changes. Our findings support the view that in MS MP might affect the inflammatory process of demyelination by a selective and dissociative effect on T-suppressor/cytotoxic cells in the PB and CSF.     

CD4 and CD8 lymphocyte subsets in cerebrospinal fluid and peripheral blood from patients with multiple sclerosis, meningitis and normal controls

Objectives - To study the distribution of CD4⁺ and CD8⁺ T-cell subsets in cerebrospinal fluid (CSF) and peripheral blood from patients with multiple sclerosis (MS), meningitis, other neurological diseases and healthy controls.
Material and methods - The expression of markers for naive and memory cells (CD45RA⁺ and CD45RO⁺), and helper/inducer cells (CD29⁺) on CD4⁺ cells as well as CD45RO⁺ and killer/effector (S6F1⁺) on CD8⁺ cells was investigated in cerebrospinal fluid (CSF) and peripheral blood from patients with multiple sclerosis (n=28), meningitis (n = 13), other neurological diseases (n = 16), and healthy controls (n = 16) by 2-color flow cytometry.
Results - The majority of T cells in the CSF of the 4 groups exhibited the phenotype of memory cells (CD45RO⁺) on both CD4⁺ and CD8⁺ cells. The proportion of helper/inducer (CD29TD4⁺ in CD4⁺) cells was also larger in the CSF compared to peripheral blood in the 3 patient groups and controls investigated. In contrast, CD8⁺ cells with killer/effector (S6F1+) phenotype were fewer in CSF compared to peripheral blood in all 4 groups. There were no significant differences between patients and controls regarding the distribution of these activation markers in the CSF or peripheral blood.
Conclusion - Our observations support the notion that activated T cells of both CD4⁺ and CD8⁺ phenotype selectively pass the blood-brain barrier under both pathological and normal conditions.     

CD45RA+ ICAM-3+ lymphocytes in cerebrospinal fluid and blood as markers of disease activity in patients with multiple sclerosis

OBJECTIVES: Autoreactive T cells targeted against antigens of the myelin sheath are suggested to play an important role in the pathogenesis of multiple sclerosis (MS). Naive (CD45RA+) T cells and intercellular adhesion molecule-3 (ICAM-3) are markers for un-activated lymphocytes. This study was performed to investigate, whether the expression levels of these antigens both on cerebrospinal fluid (CSF) and peripheral blood lymphocytes can be used as activity markers in MS. MATERIALS AND METHODS: Corresponding blood and CSF samples were obtained from 31 patients with relapsing-remitting MS. Of the 31 MS patients 23 were suffering from acute relapses at the time of examination and all of them were treated with high-dose methylprednisolone (MP). Blood was collected again on the 10th day of therapy and after 3 months. The control group consisted of 12 healthy persons. Two-color flow cytometry was performed to evaluate the percentage of both CD45RA+ and ICAM-3+ cells within the lymphocyte population. RESULTS: The percentage of CD45RA+ ICAM-3+ cells in the CSF of MS patients with relapses was significantly increased compared to patients in remission (P<0.05). In blood, a significantly lower percentage of CD45RA+ ICAM-3+ lymphocytes was found in both patient groups compared to healthy controls (Relapse: P<0.05, Remission: P<0.10). Additionally, we found a significant increase (P < 0.01) in the percentage of CD45RA+ ICAM-3+ lymphocytes in blood of MS patients suffering from acute relapse on the 10th day of high-dose MP treatment. CONCLUSION: Our data suggest that the percentage of CD45RA+ ICAM-3+ lymphocytes in CSF can be used as marker of disease activity in MS patients.     

Chemokine receptors associated with immunity within and outside the central nervous system in early relapsing-remitting multiple sclerosis

Thirty-four patients with early relapsing-remitting multiple sclerosis (RRMS) were studied to clarify the differences in chemokine receptor usage by blood and cerebrospinal fluid (CSF) lymphocytes relevant to the pathogenesis of MS. A total of 45 examinations (33 active and 12 inactive stages) revealed that circulating CD4+CXCR3+ T helper 1 (Th1) cells were increased in active MS patients and correlated with the number of gadolinium-enhanced lesions on magnetic resonance (MR) images. In contrast, CSF samples obtained during active stages were characterized by a decrease in the percentage of CD8+CXCR3+ T cells, which was inversely correlated with CSF cell count and intra-blood-brain barrier (BBB) IgG production.     

The activation of memory CD4(+) T cells and CD8(+) T cells in patients with multiple sclerosis

To reevaluate whether an association exists between the clinical course of multiple sclerosis (MS) and the activation of memory T cells, we investigated the phenotype of T cells in peripheral blood and cerebrospinal fluid (CSF) of patients with MS using five-color flow cytometry. A cross-sectional study with 39 relapsing-remitting MS patients demonstrated that the percentage of CD25(+)CD45RO(+)CD4(+)CD3(+) cells was significantly increased in peripheral blood as well as in CSF of active MS patients compared with inactive MS patients. A longitudinal study with 11 relapsing-remitting MS patients also showed a higher percentage of CD25(+)CD45RO(+)CD4(+)CD3(+) cells in peripheral blood at the phase of exacerbation than during remission. On the other hand, regardless of the disease activity, the percentage of CD25(+)CD45RO(+)CD8(+)CD3(+) cells in peripheral blood was significantly higher in patients with MS than in healthy control subjects. A lower percentage of CD25(+)CD45RO(+)CD8(+)CD3(+) cells in CSF was observed in active MS patients compared with inactive MS patients. These results suggest that the activation of memory CD4(+) T cells is associated with the exacerbation of MS and activation of memory CD8(+) T cells reflects systemic immunological dysregulation in MS patients. Transient as well as continuous activation of T cells by recall antigens may be involved in the disease course of MS.     

CD5 B cells and CD48 T cells in neuroimmunological diseases

Using 2- and 3-colour FACS analysis we found increased levels of fetal-type CD5+ B cells and CD4-8- T cells in cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS) and aseptic meningitis (AM) compared to control probands with muscular tension headache (TH). Similar differences were found for CD5+ B cells in peripheral blood, but at lower levels. CD4-8- T cells in blood exceeded those in CSF in all patient groups, with the exception of relapsing remitting MS, revealing the highest values in AM. There was a positive correlation between CD4-8- T cells and T cell receptor (TCR) gamma delta bearing T cells in blood and CSF. The double-negative T cells exceeded the TCR gamma delta T cells by about 1%. A positive correlation between CD5+ B cells and CD4-8- T cell level in CSF was found in MS and AM, but not in TH, nor in blood of any patient group. HLA-DR expression was lower in CD5+ B cells than in CD5- B cells. We conclude that fetal-type lymphocytes are enriched in CSF compartment of patients with inflammatory diseases of the central nervous system, irrespective of autoimmune mechanisms involved, but the function of CD5+ B cells is mainly to produce the autoantibodies.     

Preferential increase of IL-2R+ CD4+ T cells and CD45RB- CD4+ T cells in the central nervous system in experimental allergic encephalomyelitis.

We examined lymphocytes isolated from the spinal cord (SC), peripheral blood (PB) and lymph nodes (LN) draining the immunization site of Lewis rats with acute experimental allergic encephalomyelitis (EAE). Cells were analysed for T cell subset markers CD4 (mAb W3/25) and CD8 (mAb OX8), for IL-2R (mAb OX39), and for high molecular mass leukocyte common antigen (LCA, CD45RB) expression (mAb OX22). T cells expressing high (CD45RB+) or low (CD45RB-) molecular mass LCA are of different maturational stages and/or separate lineages. CD4+ T cells were more predominant in SC than in PB and LN; CD8+ T cells were scarce in SC but common in PB and LN. Activated CD4+ T cells (IL-2R+) were common in the SC and LN but infrequent in blood. CD4+ T cells that were CD45RB+ were scarce in the SC. In contrast, the majority of CD4+ T cells in the PB and LN were CD45RB+. The preferential accumulation of IL-2R+ CD4+ T cells and of CD45RB- CD4+ T cells in the central nervous system (CNS) indicates that a selective mechanism directs cell egress into CNS lesions in EAE.