Lymphocytes In Infectious Mononucleosis Research Articles

Pyknotic Lymphocytes In Infectious Mononucleosis

Context Pyknotic lymphocytes were infrequently observed in routine blood film evaluation of patients with clinical infectious mononucleosis. A marked increase in frequency was observed in 1995-1997. Objective To characterize the cause of these changes. Design Collection of samples from patients (25) with clinical infectious mononucleosis to ascertain the effect of anticoagulant and/or time lapse on lymphocytes and to correlate with monospot or Epstein-Barr virus antibody testing. Control samples (33), mixed hematopoietic disease (29) and lymphoproliferative disorders (36) were obtained also. Additional patients (53), identified by variant lymphocyte morphology during routine CBC’s, were verified by monospot or EBV testing and slides were made at 24 and 48 hours for differentials. Finally, single specimens (86) were obtained to establish predictability or correlation between pyknotic cells and monospot testing Setting Inpatient and outpatient hematology laboratory. Results Patients with clinical infectious mononucleosis demonstrated 8-10% pyknotic lymphocytes in 24 and 48 hour samples in all three anticoagulants (see Figure 1) compared with controls, “other diseases” (Table 2) and lymphoproliferative disorders (Table 3). An unexpected predictive correlation of pyknotic cells with positive monospot or Epstein-Barr Virus antibodies was demonstrated when pyknotic cells were seen with or without significant atypical lymphocytes during daily routine differential counting. Conclusion Observation of pyknotic lymphocytes adds a significant and inexpensive element to the diagnosis of infectious mononucleosis and consideration of Cytomegalic Virus infection in older patient Disclosures: No relevant conflicts of interest to declare.

Abortive lytic Epstein–Barr virus replication in tonsil-B lymphocytes in infectious mononucleosis and a subset of the chronic fatigue syndrome

Correspondence: A Martin Lerner 32804 Pierce Road, Beverly Hills, MI, 48025, USA Tel +1 248 540 9866 Fax +1 248 540 0139 Email amartinlerner@yahoo.com Abstract: A systematic 2001–2007 review of 142 chronic fatigue syndrome (CFS) patients identified 106 CFS patients with elevated serum IgG antibodies to the herpesviruses Epstein– Barr virus (EBV), cytomegalovirus, or human herpesvirus (HHV) 6 in single or multiple infections, with no other co-infections detected. We named these 106 patients group-A CFS. Eighty-six of these 106 group-A CFS patients (81%) had elevated EBV early antibody, early antigen (diffuse), serum titers. A small group of six patients in the group-A EBV subset of CFS, additionally, had repetitive elevated-serum titers of antibody to the early lytic replicationencoded proteins, EBV dUTPase, and EBV DNA polymerase. The presence of these serum antibodies to EBV dUTPase and EBV DNA polymerase indicated EBV abortive lytic replication in these 6 CFS patients. None of 20 random control people (ageand sex-matched, with blood drawn at a commercial laboratory) had elevated serum titers of antibody to EBV dUTPase or EBV DNA polymerase (P , 0.01). This finding needs verification in a larger group of EBV CFS subset patients, but if corroborated, it may represent a molecular marker for diagnosing the EBV subset of CFS. We review evidence that EBV abortive lytic replication with unassembled viral proteins in the blood may be the same in infectious mononucleosis (IM) and a subset of CFS. EBV-abortive lytic replication in tonsil plasma cells is dominant in IM. No complete lytic virion is in the blood of IM or CFS patients. Complications of CFS and IM include cardiomyopathy and encephalopathy. Circulating abortive lytic-encoded EBV proteins (eg, EBV dUTPase, EBV DNA polymerase, and others) may be common to IM and CFS. The intensity and duration of the circulating EBV-encoded proteins might differentiate the IM and EBV subsets of CFS. Abortive lytic replication may be a pathogenic mechanism for EBV disease. EBV (HHV4) is a gamma herpesvirus composed of dsDNA about 170 Kb in length. For this discussion, there are early genes (including expressions of encoded proteins EBV dUTPase, DNA polymerase, and nuclear proteins) and late genes (including expressions of capsid and membrane proteins). Abortive infection infers incomplete virion expressions of either early or late proteins, but the virion is incomplete. The lytic virus infers a complete virion. The pathologic consequences of EBV abortive replication are currently being investigated by authors.

Absence of Epstein-Barr virus-specific, HLA class II-restricted CD4+ cytotoxic T lymphocytes in infectious mononucleosis

Cytotoxic T lymphocytes (CTL) with the CD4+ phenotype that recognize major histocompatibility complex (MHC) class II antigens are detectable very frequently in cultures of human alloreactive or virus-specific T cells. The significance of these CD4+ CTL for an immune reaction in vivo is not clear. Since Epstein-Barr virus (EBV) transformed B cells express HLA-class I and class II antigens equally well both CD8+ and CD4+ CTL should be stimulated during an acute EBV infection. We analysed the MHC specificity and the phenotype of EBV-specific CTL from patients with infectious mononucleosis (IM). When tested directly without any previous culture, T cells from patients in the acute phase of IM showed specific MHC-restricted cytotoxicity against the autologous B cell line. Addition of a HLA class I specific monoclonal antibody (MoAb) but not of a HLA class II specific MoAb resulted in a complete blocking of the lytic activity. Cell sorting revealed that the entire cytotoxic activity was present in the CD8+ fraction whereas no specific CTL were detectable in the CD4+ fraction. The absence of cytotoxicity in CD4+ cells was not due to a lack of activation of these cells since both CD8+ and CD4+ cells were activated in situ, showing spontaneous growth in interleukin-2 (IL-2) and expressing the activation marker TP103. Frequency estimation revealed that 1/300-1/600 CD8+ but only 1/2000-1/4000 CD4+ T cells gave rise to a specific CTL colony after 10 days. If CD4+ colonies were tested repeatedly for cytotoxicity we found that CD4+ CTL acquired their cytotoxicity during in vitro culture. In addition, we isolated EBV-specific CD4+ T cell clones able to lyse their stimulator cells in the presence but not in the absence of lectin, even after a long period of culture. Taken together our results show that cytotoxicity mediated by CD4+ T cells does not play a role in an anti-viral immune response.

Epstein-Barr virus-carrying B cells in the blood during acute infectious mononucleosis give rise to lymphoblastoid lines in vitro by release of transforming virus and by proliferation

In accordance with earlier studies, we detected higher numbers of Epstein-Barr virus (EBV)-carrying lymphocytes (B-EBV) in the blood of acute infectious mononucleosis (IM) patients and higher amounts of transforming EBV particles in the saliva compared to healthy seropositive individuals. B cells grew in cultures seeded with the low and high density IM lymphocytes. The majority of B cells which grew acquired the infection in vitro (2-step outgrowth), because addition of virus neutralizing antibodies considerably reduced the emergence of lymphoblastoid cell lines (LCLs). Only the minority of the explanted B-EBV cells proliferated. The antiviral drug phosphonoformate (PFA) did not influence the frequency of 2-step LCLs in the IM cultures. This may indicate that a large proportion of EBV carrying B cells have already entered the viral productive cycle in vivo and passed the PFA-sensitive stage at the time of explantation. Earlier experiments with blood of healthy seropositive individuals showed an inhibitory effect of PFA on the generation of LCLs. One healthy individual who entered this study as a control, probably had a reactivated EBV infection as judged by the anti-EA activity in his serum and the high level of virus in his saliva. He had antibodies against EBV nuclear antigens (EBNA), and therefore he did not have a primary infection at the time of the test. Judged by the number of wells with B cell growth, the frequency of virus-carrying B cells in his blood was low. It seems that anti-EBV immunity can control the number of infected B cells in the blood, but does not influence the virus load in the epithelial cells.

Selective expression of the p70 subunit of the interleukin-2 receptor on lymphocytes from patients with infectious mononucleosis

The lymphocytosis manifested in infectious mononucleosis (IM) during acute phase is ascribed to a reactive expansion of CD8+ T lymphocytes caused by Epstein-Barr virus (EBV)-infected B lymphocytes. Expression of HLA-DR antigen on IM lymphocytes suggests that these T lymphocytes are somehow activated in vivo. In the present study, we analyzed the interleukin-2 (IL-2) receptor expression on lymphocytes from six patients with acute IM. Radiolabeled IL-2 binding assay revealed that IM lymphocytes from all patients examined had a considerable number of IL-2 binding sites with an intermediate affinity, although they did not express the IL-2 receptor recognized by anti-Tac antibody (p55). The number of binding sites (1,070 to 4,600 sites per cell) was larger than that of a normal, resting T lymphocyte-enriched population (650 sites per cell). Furthermore, IM lymphocytes showed marked proliferative responses to higher concentrations of IL-2, which were almost completely blocked by an anti-p70 IL-2 receptor antibody, indicating that their IL-2 receptor is a functional receptor. The results of an affinity cross-linking study seem to indicate that the IL-2 receptor expressed on IM lymphocytes is p70, the second chain of the IL-2 receptor distinct from p55. Flow cytometric analysis following immunofluorescent staining with anti-p70 IL-2 receptor antibody confirmed p70 expression on CD8+ HLA-DR+ lymphocytes. These data suggest that p70 IL-2 receptor expression is involved in the immune response triggered by EBV infection.

Selective Expression of the p70 Subunit of the Interleukin-2 Receptor on Lymphocytes from Patients with Infectious Mononucleosis

The lymphocytosis manifested in infectious mononucleosis (IM) during acute phase is ascribed to a reactive expansion of CD8+ T lymphocytes caused by Epstein-Barr virus (EBV)-infected B lymphocytes. Expression of HLA-DR antigen on IM lymphocytes suggests that these T lymphocytes are somehow activated in vivo. In the present study, we analyzed the interleukin-2 (IL-2) receptor expression on lymphocytes from six patients with acute IM. Radiolabeled IL-2 binding assay revealed that IM lymphocytes from all patients examined had a considerable number of IL-2 binding sites with an intermediate affinity, although they did not express the IL-2 receptor recognized by anti-Tac antibody (p55). The number of binding sites (1,070 to 4,600 sites per cell) was larger than that of a normal, resting T lymphocyte-enriched population (650 sites per cell). Furthermore, IM lymphocytes showed marked proliferative responses to higher concentrations of IL-2, which were almost completely blocked by an anti-p70 IL-2 receptor antibody, indicating that their IL-2 receptor is a functional receptor. The results of an affinity cross-linking study seem to indicate that the IL-2 receptor expressed on IM lymphocytes is p70, the second chain of the IL-2 receptor distinct from p55. Flow cytometric analysis following immunofluorescent staining with anti-p70 IL-2 receptor antibody confirmed p70 expression on CD8+ HLA-DR+ lymphocytes. These data suggest that p70 IL-2 receptor expression is involved in the immune response triggered by EBV infection.

CD8+ T cell subsets of cytotoxic T lymphocytes induced by Epstein-Barr virus infection in infectious mononucleosis.

Mononuclear peripheral blood lymphocytes (PBL) from patient with infectious mononucleosis (IM) were tested in a 51Cr-release assay for cytotoxicity against autologous and allogeneic lymphoblastoid cell line (LCL), or Epstein-Barr virus (EBV)-genome positive and negative cell line. In acute phase, PBL lyse an autologous LCL as well as allogeneic LCL (Wa cells). High levels of cytotoxicity were observed in the combinations between effector and target cells sharing HLA-Class 1 product. EBV-genome positive Daudi and Raji cells which lack HLA-Class 1 antigen and have mismactched HLA-Class 1 antigen, respectively showed resistance to killing. EBV-genome negative tumor cells except NK sensitive K562 cells were not killed by IM lymphocytes. However, the IM lymphocytes without atypical form in convalescent phase failed to show killing activity against autologous and allogeneic LCL. These findings suggest that cell surface membrane antigen structure on EBV-infected LCL may be able to explain the recognition and triggering of lysis of target cells by HLA-Class 1 restricted cytotoxic T cells (CTL) from acute IM. Phenotypic analysis of PBL with atypical form from IM was made by two-color flow cytometry. The data demonstrate that CD8+ T cells quantitatively represent the major population of lymphocytes expanded during acute IM. Furthermore, approximately 70% of these CD8+ T cells express HLA-DR on these surface, suggesting that they have undergone activation. However, IL 2R (CD25 antigen) expression was not significantly elevated on activated T cells. The salient profile on cytofluorographs of an acute IM was the increased number of CD3+CD19-, CD8+CD11b-, CD8+CD28+ and CD8+S6F1+ cells. However, CD3-CD19+, CD8+CD11b+, CD8+S6F1-, CD4+Leu8- and CD25+HLA-DR+ antigens were little expressed. Increased number of CD8+CD11b-, CD8+CD28+ and CD8+S6F1+ cells, which are regarded as CTL were reduced according to the improvement of the clinical symptoms and laboratory findings. These results together with HLA typing analysis suggested a possibility HLA-Class 1 restriction of the CTL with surface phenotype of CD8+CD11b-, CD8+CD28+, and CD8+S6F1+.

Characterization of the T cell-mediated cellular cytotoxicity during acute infectious mononucleosis.

Primary infection with EBV during acute infectious mononucleosis (IM) is associated with a cytotoxic response against allogeneic target cells. C depletion with anti-CD3 (OKT3) and anti-CD8 (OKT8) mAb decreased the allogeneic cytolysis of two EBV-infected lymphoblastoid cell lines (LCL) by 96% and 89%, respectively. Complement depletion with the NK cell-specific mAb Leu-11b and NKH-1a resulted in only a slight decrease (less than 35%) in the lysis of these LCL. mAb inhibition studies with OKT3 and OKT8 inhibited the allogeneic lysis of two LCL by 87% and 82%, respectively. The alloreactive cytotoxic response was strongly inhibited by mAb specific for MHC class I determinants (W6/32, 65% inhibition and BBM.1, 58% inhibition). Acute IM lymphocytes lysed the allogeneic EBV-negative cell lines HSB2 (45%) and HTLV-1 T cell lines (16%). NK cell-depleted lymphocytes from an acute IM patient demonstrated preferential lysis of K562 transfected with human HLA-A2 (73%) compared with the K562 transfected control (20%). Cold target competition studies with allogeneic and autologous target and competitor LCL demonstrated no significant competitive inhibition between allogeneic and autologous cells. We interpret these results as evidence that 1) the acute IM-alloreactive cytotoxic response is mediated primarily by CTL; 2) these alloreactive CTL lyse allogeneic target cells irrespective of EBV antigenic expression; 3) MHC class I expression is sufficient for allogeneic recognition and lysis of target cells; 4) distinct effector CTL populations mediate lysis of autologous and allogeneic target cells; and 5) during acute IM, EBV infection results in the induction of both virus-specific and alloreactive CTL populations.

T lymphocytes in infectious mononucleosis; Effect of IL‐2 on the outgrowth of Epstein‐Barr virus‐infected cells

The addition of interleukin-2 (IL-2) to lymphocyte cultures from acute infectious mononucleosis (IM) donors dramatically increased the incidence of regression in such cultures and resulted in the emergence of an IL-2 dependent, CD3 Epstein-Barr virus nuclear antigen (EBNA)-negative cell population. Corresponding cultures seeded in the absence of IL-2 rarely regressed and were quickly dominated by IL-2 independent, CD3-negative, EBNA-positive cells. Lymphocyte cultures from Epstein-Barr virus (EBV) seropositive donors showed enhanced regression in the presence of IL-2 but failed to regress after the removal of the E-rosetting population. Cultures from EBV-seronegative donors showed no evidence of regression in the presence or absence of IL-2. E-rosetting cells isolated from cultures from acute IM donors that had been cultured in the presence of IL-2 lysed autologous and allogeneic lymphoblastoid cell lines.

Infectious mononucleosis: increase of high-affinity E-receptor-bearing lymphocytes.

The increase of T lymphocytes in infectious mononucleosis (IM) is shown to be due to an increase of 'active' (early erythrocyte rosette-forming) T cells: 67.2 +/- 18.3% of IM lymphocytes were 'active' versus 34.7 +/- 14.9% of control lymphocytes. IM was also associated with an increase of lymphocytes demonstrating E receptors at 20 degrees C (E20-R). This phenomenon was not related to the heterophile antibody titre and could not be demonstrated with ox or rabbit erythrocytes. Patients with other lymphoproliferative diseases did not show an increase of E20-R-positive cells or of 'active' erythrocyte rosette-forming cells (E-RFC). Re-rosetting experiments indicated that E20-R and 'active' E-RFC belong to overlapping populations of cells. A double-gradient separation technique was shown to be superior to the conventional Ficoll-Isopaque method for the demonstration of 'active' and total T cells. A high proportion of T lymphocytes were also recovered in the granulocyte layer by this technique, indicating a selective loss of these cells by the conventional technique.

The cellular basis for viral-induced immunodeficiency: analysis by monoclonal antibodies.

Viral infections are often associated with immunodeficiency states. Although T lymphocytes have been thought to suppress the host's response, the precise etiology remains unclear. Therefore, we characterized T lymphocytes from six patients during both acute and convalescent phases of infectious mononucleosis (IM) with monoclonal antibodies (titer, 10(-5) to 10(-7) to antigens restricted to the TH2- helper (T4) and TH2 suppressor (T5) T cell subsets as well as to a common T cell antigen (T3) and HLA-D related Ia antigens. It was found that during acute infectious mononucleosis, there is both activation and increase of suppressor T cells (T5+, Ia+ phenotype). Fuctionally, the acute IM lymphocytes suppress autologous T cell proliferation to antigens as well as pokeweed mitogen driven B cell immunoglobulin production. In contrast, convalescence is associated with a return to normal of T cell subsets and immune function. These results demonstrate that viral infections can preferentially activate a specific T cell subset and suppress the overall human immune response.

Hand-mirror lymphocytes in infectious mononucleosis

The identification of a morphologically unique lymphocyte in the peripheral blood of patients with infectious mononucleosis (IM) led to additional studies. Examination of Wright-stained smears of EDTA anticoagulated blood obtained from 25 patients with IM at presentation revealed significantly increased (p less than 0.0001) percentages of hand-mirror lymphocytes (HML) (mean 9.2%) compared with normal controls (mean 2.7%) or controls with nonspecific viral syndromes (mean 2.2%). Follow-up blood samples obtained on 10 of these patients demonstrated a marked increase in the HML count (mean 12.1%) that coincided with the onset of recovery. E-rosette separation of Ficoll-Hypaque-derived peripheral blood lymphocytes from 5 patients with early recovery IM showed the HML to be present almost exclusively in the T-cell population, representing about 25% of the T cells. Identical procedures on 5 controls showed less than 5% HML in the T-cell sample. Cytochemistries supported a T-cell derivation for HML. Electron microscopic examination of HML in IM demonstrated that these cells have unique ultrastructural features that may be related to functions of cellular attachment and cytotoxicity.

Hand-Mirror Lymphocytes in Infectious Mononucleosis

The identification of a morphologically unique lymphocyte in the peripheral blood of patients with infectious mononucleosis (IM) led to additional studies. Examination of Wright-stained smears of EDTA anticoagulated blood obtained from 25 patients with IM at presentation revealed significantly increased (p < 0.0001) percentages of hand-mirror lymphocytes (HMD (mean 9.2%) compared with normal controls (mean 2.7%) or controls with nonspecific viral syndromes (mean 2.2%). Follow-up blood samples obtained on 10 of these patients demonstrated a marked increase in the HML count (mean 23.1%) that coincided with the onset of recovery. E-rosette separation of Ficoll-Hypaque-derived peripheral blood lymphocytes from 5 patients with early recovery IM showed the HML to be present almost exclusively in the T-cell population, representing about 25% of the T cells. Identical procedures on 5 controls showed less than 5% HML in the T-cell sample. Cytochemistries supported a T-cell derivation for HML. Electron microscopic examination of HML in IM demonstrated that these cells have unique ultrastructural features that may be related to functions of cellular attachment and cytotoxicity.

Autoantibody to “intermediate filaments” in infectious mononucleosis

By employing indirect immunofluorescent staining we detected autoantibodies against circulating lymphoblasts in the sera of two patients with acute infectious mononucleosis (IM). The target structures were identified as intermediate filaments (IMF) by their antigenic and biochemical properties. High titers of anti-IMF autoantibody were detected in 32 of 48 (67%) IM patient sera but not in control sera. The antibodies were usually of IgM class. The presence of anti-IMF antibodies did not correlate with anti-smooth muscle antibodies, and absorption studies revealed that the specificity of these antibodies differed from that of heterophilic (Paul-Bunnell) antibodies. The results may be interpreted as suggesting that the rapid turnover of lymphocytes in IM may be associated with a release of autoimmunogenic cytoplasmic intermediate(-sized) filaments.

Ultrastructural, Cytochemical, and Membrane Surface Marker Characteristics of the Atypical Lymphocytes in Infectious Mononucleosis

Abstract Atypical lymphocytes from nine young adults with acute infectious mononucleosis (IM) were studied for morphologic, ultrastructural, cytochemical, and membrane surface marker characteristics. There was an absolute increase in T lymphocytes in the patients. Atypical lymphocytes accounted for 83%-96% of the lymphocyte population. These lymphocytes contained cytoplasmic inclusions which ranged in size from 1000 to 6000 A, were usually membrane bound, and consisted of parallel arrays of microtubulelike structures. The inclusions, which have been referred to as parallel tubular arrays (PTA), were found in 15%-75% of the lymphocytes from the IM patients. Ultrastructural cytochemical methods demonstrated acid phosphatase activity within many of the membrane-bound PTA. The function of the PTA is unknown. Since they were observed only in the lymphocytes which appeared to correspond to the atypical lymphocytes on light microscopy, the majority of which typed as T cells, there appears to be an association between PTA and T lymphocytes. It is possible that PTA identify a specific subset of T lymphocytes which is expanded in IM. Alternatively, PTA may be a transient finding in lymphocytes appearing only in certain biologic states of the cell such as during T-lymphocyte activation.

Ultrastructural, cytochemical, and membrane surface marker characteristics of the atypical lymphocytes in infectious mononucleosis

Atypical lymphocytes from nine young adults with acute infectious mononucleosis (IM) were studied for morphologic, ultrastructural, cytochemical, and membrane surface marker characteristics. There was an absolute increase in T lymphocytes in the patients. Atypical lymphocytes accounted for 83%-96% of the lymphocyte population. These lymphocytes contained cytoplasmic inclusions which ranged in size from 1000 to 6000 A, were usually membrane bound, and consisted of parallel arrays of microtubulelike structures. The inclusions, which have been referred to as parallel tubular arrays (PTA), were found in 15%-75% of the lymphocytes from the IM patients. Ultrastructural cytochemical methods demonstrated acid phosphatase activity within many of the membrane-bound PTA. The function of the PTA is unknown. Since they were observed only in the lymphocytes which appeared to correspond to the atypical lymphocytes on light microscopy, the majority of which typed as T cells, there appears to be an association between PTA and T lymphocytes. It is possible that PTA identify a specific subset of T lymphocytes which is expanded in IM. Alternatively, PTA may be a transient finding in lymphocytes appearing only in certain biologic states of the cell such as during T-lymphocyte activation.

Atypical lymphocytes in acute infectious mononucleosis. Identification by multiple T and B lymphocyte markers.

Abstract Atypical lymphocytes from four patients with acute infectious mononucleosis were tested for the presence of five separate markers of thymic-derived (T) and bone-marrow-derived (B) lymphocytes. This test was done to rule out the possibility that the previously described sheep erythrocyte rosetting capacity (a normal T-cell marker) of atypical lymphocytes in infectious mononucleosis was due to passive adsorption or production of heterophil (anti-sheep erythrocyte) antibody on the surface of B lymphocytes and was therefore a false-positive reaction. The vast majority of atypical lymphocytes had sheep erythrocyte receptors as well as human T-lymphocyte specific antigens and lacked three reliable B-cell markers (complement receptors, surface immunoglobulin, and human B lymphocyte specific antigens). Since Epstein-Barr virus, the etiologic agent of infectious mononucleosis, has recently been shown to infect only B lymphocytes, the finding that the atypical lymphocytes are indeed T cells suggests that t...

The nature of the atypical lymphocyte in infectious mononucleosis

The nature of the circulating atypical lymphocytes in infectious mononucleosis (I.M.) has been examined by a battery of techniques in order to determine whether they are of bone marrow (B-lymphocyte) or thymic (T-lymphocyte) origin. To identify T-lymphocytes, the spontaneous sheep erythrocyte rosette technique was used; to identify B-lymphocytes, a rosette method using sheep erythrocytes coated with pure anti-human F(ab') 2 was employed. These methods were used in combination with tritiated thymidine incorporation and radioautography to identify the dividing B- or T-lymphocytes. The results obtained indicate that there is a 6.2-fold increase in circulating T-lymphocytes and a 5.3-fold increase in B-lymphocytes in patients with I.M. as compared to normal controls. The percentage of tritiated thymidine labeled mononuclear cells was less than 0.2% in five normal controls while it ranged from 4.8 to 9.4% (mean 6.6%) in five I.M. patients. There was a marked increase in the number of labeled circulating T- and B-lymphocytes to 313/mm 3 (normal < 1.5/mm 3) and 136/mm 3 (normal < 1/mm 3), respectively. These results demonstrate that both the T- and B-lymphocytes are part of the atypical lymphocyte population and are stimulated to divide in I.M.

Stimulation of Peripheral Lymphocytes by Allogeneic and Autochthonous Mononucleosis Lymphocyte Cell Lines

Abstract Cultures of peripheral lymphocytes obtained during the acute phase of infectious mononucleosis (IM) were established. Mitomycin C-inhibited cells of these cultures caused abnormally high transformation rates in mixed cultures (MLR) with allogeneic peripheral lymphocytes and to a lesser degree they also stimulated autochthonous peripheral lymphocytes obtained from the same persons 3 to 9 months after their acute disease. This stimulation seems not to be caused by Epstein-Barr virus (EBV), present in the IM-cultures, because concentrated EBV preparations did not stimulate the convalescent lymphocytes and allogeneic lymphocytes from infants with and without circulating EBV antibodies responded equally well in the MLR with cultured IM lymphocytes. Circulating antibodies against surface antigens of autochthonous acute phase IM lymphocytes, stored in liquid nitrogen or cultured, were demonstrated in convalescent IM sera by the indirect membrane fluorescence technique. Blastogenic activity for both allogeneic and autochthonous lymphocytes was found in the cell-free supernatants of these IM lymphocyte cultures and was probably associated with cell membrane fragments.

The Proliferation of Infectious Mononucleosis Lymphocytes in vitro

The Proliferation of Infectious Mononucleosis Lymphocytes in vitro