The atypical lymphocyte

Hematological parameters: is there a difference between those released by the hematological analyzer and to the customer?

OBJECTIVE

This study aimed to compare the hematological parameters released by hematological analyzers with those released in customer reports.

METHODS

We conducted a descriptive study in the laboratories of a medium-sized municipality in the state of Minas Gerais registered in the National Register of Health Establishments. Interviews were conducted using a questionnaire to obtain information regarding the parameters released by the analyzers and those available in the customer's report.

RESULTS

Sixteen laboratories were evaluated, and none of them released all the parameters obtained from the hematological analyzers to customers. The red blood cell distribution width was released in 88% of the laboratories, atypical lymphocytes in 70%, mean platelet volume in 50%, platelet distribution width and platelet count in 20%. No laboratory released information on reticulocytes, fraction of immature reticulocytes and immature granulocytes, nucleated erythrocyte count, immature platelet fraction and reticulocyte hemoglobin, and large platelet rate.

CONCLUSION

All evaluated clinical analysis laboratories had at least one parameter that was not released in the customer's report despite being released by the hematological analyzers. The lack of knowledge on the part of professionals about the clinical importance of each parameter of the complete blood count results in a loss in patient assessment, and it is important to include these parameters in the complete blood count report.

EBV Persistence--Introducing the Virus

Persistent infection by EBV is explained by the germinal center model (GCM) which provides a satisfying and currently the only explanation for EBVs disparate biology. Since the GCM touches on every aspect of the virus, this chapter will serve as an introduction to the subsequent chapters. EBV is B lymphotropic, and its biology closely follows that of normal mature B lymphocytes. The virus persists quiescently in resting memory B cells for the lifetime of the host in a non-pathogenic state that is also invisible to the immune response. To access this compartment, the virus infects naïve B cells in the lymphoepithelium of the tonsils and activates these cells using the growth transcription program. These cells migrate to the GC where they switch to a more limited transcription program, the default program, which helps rescue them into the memory compartment where the virus persists. For egress, the infected memory cells return to the lymphoepithelium where they occasionally differentiate into plasma cells activating viral replication. The released virus can either infect more naïve B cells or be amplified in the epithelium for shedding. This cycle of infection and the quiescent state in memory B cells allow for lifetime persistence at a very low level that is remarkably stable over time. Mathematically, this is a stable fixed point where the mechanisms regulating persistence drive the state back to equilibrium when perturbed. This is the GCM of EBV persistence. Other possible sites and mechanisms of persistence will also be discussed.

Epstein-barr virus infection masquerading as acute leukemia: a report of two cases and review of literature

Epstein-Barr virus (EBV) is the first herpes virus to be completely sequenced. It is implicated in diseases from the benign infectious mononucleosis to malignant nasopharyngeal carcinoma, Burkitt's lymphoma and primary CNS lymphoma in AIDS patients. It has also been found to be associated with some miscellaneous diseases like chronic fatigue syndrome, multiple sclerosis etc. however causality still remains an issue of debate. As the virus mainly targets the lymphomonuclear cells and the reticuloendothelial system of the body, it's various manifestations are often mistaken as leukemic malignancies. We report two such cases of young adults who had been diagnosed as having acute leukemia on the basis of atypical cells in the peripheral blood. One patient later turned out to be a classical infectious mononucleosis and second patient had EBV associated hemophagocytic lymphohistiocytosis syndrome.

Why does my patient have leukocytosis?

Leukocytosis is one of the most common laboratory abnormalities in medicine, and one of the most frequent reasons for hematologic consultation. Effective evaluation of leukocytosis requires an attentive history, careful physical examination, meticulous review of the complete blood count and peripheral blood smear, judicious application of laboratory and radiologic testing, and thoughtful analysis. Definitive diagnosis may require bone marrow aspiration and biopsy, imaging studies, and specialized molecular tests. The differential diagnosis of leukocytosis includes physiologic responses to a broad range of infectious and inflammatory processes, as well as numerous primary hematologic disorders such as leukemias, lymphomas, and myeloproliferative neoplasms.

A case presenting with rapid renal damage caused by immunoglobulin D lambda-type multiple myeloma accompanied by granular lymphocyte proliferative disorder

A 69-year-old man was referred to our hospital for severe anemia. The atypical lymphocyte count, including granular lymphocytes, was 2,750/μL. Lymphocyte surface marker analysis showed CD3+, CD5+, CD16+, and CD56+ cells. Mixed T cell- and natural killer cell-type granular lymphocyte proliferative disorder (GLPD) was diagnosed. Because his serum creatinine levels deteriorated rapidly over the next 3 months, from 0.96 to 3.27 mg/dL, he was admitted to our hospital. The serum levels of immunoglobulins (Ig) other than IgD had decreased, and monoclonal protein was detected in the gamma-globulin region. Immunoelectrophoresis revealed IgD and lambda (λ) proteins in the serum and λ-type Bence-Jones protein in the urine. Renal biopsy examination revealed widespread tubular atrophy and interstitial fibrosis, and cast formation with λ protein deposits in tubular lumens, indicating cast nephropathy. These results indicated that the rapid renal damage was caused by IgD λ-type multiple myeloma accompanied by GLPD. The clinical course of GLPD is not usually aggressive and the findings of physical examinations are not significant. GLPD is usually associated with cytopenia (neutropenia or anemia), viral infections, collagen diseases, neoplasms such as malignant lymphoma, or chronic infections. To date, there are only 2 case reports of GLPD accompanied by multiple myeloma but without renal function or renal histological findings. When the clinical course of GLPD is aggressive and is accompanied with rapid renal damage, multiple myeloma should be considered as a complication.

Hematologic differences in heterophile-positive and heterophile-negative infectious mononucleosis

Infectious mononucleosis (IM) due to all causes is characterized by atypical lymphocytosis. We sought to compare hematologic parameters of infectious mononucleosis due to Epstein-Barr virus (EBV) infection (heterophile antibody (HA) positive) with mononucleosis due to other causes. Mono-Latex Slide Agglutination Test results and complete blood counts (CBC) of 147 patients with mononucleosis were retrospectively analyzed. Leukocyte count, absolute lymphocyte count, and presence of atypical lymphocytes in EBV-positive and EBV-negative groups were statistically compared. We analyzed 68 EBV-positive and 79 EBV-negative cases. EBV-positive patients were significantly younger than EBV-negative patients were. Mean total WBC count and mean absolute lymphocyte count were significantly higher in EBV-positive patients. Absolute lymphocytosis, absolute leukocytosis, and atypical lymphocytosis were also significantly more frequent in EBV-positive patients. Leukopenia was more frequently seen in EBV-negative patients.

Comparison of automated haematology analysers for detection of apoptotic lymphocytes

Automated haematology analysers can rapidly provide accurate blood cell counts and white blood cell differentials. In this study, we evaluated four different haematology analysers for the detection of apoptotic lymphocytes in peripheral blood: MAXM A/L Retic, H*2, Cell-Dyn 3500 and NE-8000. With the MAXM A/L Retic haematology analyser, the apoptotic lymphocyte cluster appeared below the original lymphocyte cluster on the volume/DF1, and to the right under the original lymphocyte cluster on the volume/DF2 scattergrams. With the H*2 haematology analyser, the apoptotic polymorphonuclear lymphocytes produced a higher lobularity index on the BASO channel. With the Cell-Dyn 3500 haematology analyser, the apoptotic lymphocyte cluster appeared to the right side of the original lymphocyte cluster on the 0D/10D scattergram and to the left side of the polymorphonuclear cluster on the 90D/10D scattergram. With the NE-8000 haematology analyser, the apoptotic lymphocyte cluster was not distinguishable. Thus, apoptotic lymphocytes are readily detected on scattergrams generated by selected haematology analysers.

Infectious diseases manifested in the peripheral blood

Although primary diagnosis of infectious disease is uncommonly made from morphologic examination of a blood smear in the United States, knowledge of the distinctive morphologic features of various organisms, coupled with an understanding of the clinical and epidemiologic features of various disorders, permits recognition and diagnosis of uncommonly encountered infections. Furthermore, nonspecific manifestations of infection may provide an important clue in guiding a further diagnostic work-up.

Proportion positive for Epstein-Barr virus, cytomegalovirus, human herpesvirus 6, Toxoplasma, and human immunodeficiency virus types 1 and 2 in heterophile-negative patients with an absolute lymphocytosis or an instrument-generated atypical lymphocyte flag

OBJECTIVES

To determine the proportion of patients with evidence of an acute infection due to Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus 6 (HHV-6), Toxoplasma, or human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) in heterophile-negative patients with an absolute lymphocytosis or an instrument-generated atypical lymphocyte flag, and to develop a cost-effective testing algorithm for managing such heterophile-negative patients.

DESIGN

We conducted a prospective investigation of 70 selected outpatients who tested negative for heterophile antibody in association with an absolute lymphocytosis or instrument-generated atypical lymphocyte flag. The control population consisted of 50 patients who were heterophile negative and had a normal absolute lymphocyte count and no instrument-generated atypical lymphocyte flag.

SETTING

A large outpatient laboratory system.

INTERVENTION

Viral serology for HHV-6 was performed by immunofluorescence, and all other serologies were performed by enzyme-linked immunoassay. All testing was for immunoglobulin (Ig) M antibodies, except in the case of HIV.

RESULTS

The proportion of study patients positive for EBV was 40% (28/70); for CMV, 39% (27/70); for HHV-6, 25% (16/65); for Toxoplasma, 3% (2/70); and for HIV, 0% (0/70). All 50 control patients were negative for EBV IgM antibodies. When patients with more than 1 positive viral test were excluded from analysis, positivity was 20% (9/45) for EBV, 22% (10/45) for CMV, 9% (4/45) for HHV-6, and 2% (1/45) for Toxoplasma. Utilizing hypothesis-generating logistic regression models, Downey type II atypical lymphocytes were significantly associated with EBV positivity (P =.006), while Downey type III lymphocytes were significantly associated with HHV-6 positivity (P =.016), and there was a trend for the association of Downey type I lymphocytes with CMV positivity (P =.097).

CONCLUSIONS

A positive viral serology was identified in 70% of study patients. Multiple positive serologies complicate establishing a definitive diagnosis. Potential cost savings may be associated with the use of an appropriate testing algorithm.

Infectious mononucleosis in an outpatient population: diagnostic utility of 2 automated hematology analyzers and the sensitivity and specificity of Hoagland's criteria in heterophile-positive patients

OBJECTIVES

To determine the sensitivity and specificity of 2 modern hematology analyzers in flagging heterophile-positive patients; to determine if heterophile-positive, instrument-flagged specimens contain a larger number or a different spectrum of atypical lymphocytes; to document the overall sensitivity and specificity of Hoagland's morphologic criteria in identifying heterophile-positive patients in an outpatient population with a clinical diagnosis of mononucleosis; and to examine whether individual morphologic features might aid in the diagnosis of suspected infectious mononucleosis.

DESIGN

A prospective study of patients referred with a clinical diagnosis of infectious mononucleosis who subsequently tested positive for the heterophile antibody. The control group consisted of a similar population of patients who tested negative for the heterophile antibody.

INTERVENTION

Hematology profiles of peripheral blood samples were determined with Coulter STKS and Sysmex NE-8000 analyzers. A corresponding Wright-Giemsa-stained blood smear was subsequently examined by a single skilled technologist, who performed a 200-cell white blood cell differential and a 200-cell lymphocyte differential. A specific morphologic search was made for the presence of smudge cells or lymphocytes with cloverleaf nuclei.

RESULTS

Using a combination of all flagging criteria, the 2 analyzers identified 156 (86.2%) of 181 heterophile-positive patients as meriting further review. The sensitivity and specificity values of the Coulter analyzer in predicting positive heterophile status for the blast flag were 41% and 97.1%, respectively; for the variant lymphocyte flags, 72.4% and 79.1%, respectively; and for both flags, 40% and 98.1%, respectively. For the Sysmex analyzer, the sensitivity and specificity values in predicting positive heterophile status for the blast flag were 43.4% and 88.6%, respectively; for the variant lymphocyte flag, 15.8% and 90.8%, respectively; and for both flags, 10.5% and 96%, respectively. Considering the classic criteria developed by Hoagland, a lymphocytosis of at least 50% was present in 120 (66.3%) heterophile-positive patients, while an atypical lymphocytosis of at least 10% of the total WBC count was noted in 135 patients (74.6%). The sensitivity and specificity values of a lymphocytosis > or =50% for diagnosing heterophile-positive status were 66.3% and 84.5%, respectively, while the sensitivity and specificity of an atypical lymphocytosis > or =10% were 74.6% and 92.3%, respectively. The presence of smudge cells or cloverleaf lymphocyte nuclei was verified as having high specificity but low sensitivity for suggesting a diagnosis of infectious mononucleosis.

CONCLUSION

Although a number of patients did not meet Hoagland's criteria for the diagnosis of infectious mononucleosis, the flagging systems of modern hematology analyzers successfully identified most cases as requiring further review.

Fever, lymphadenopathy, eosinophilia, lymphocytosis, hepatitis, and dermatitis: a severe adverse reaction to minocycline

A 17-year-old female patient who had been taking oral minocycline (50 mg twice daily) for 3 weeks for acne developed an eruption that progressed to an exfoliative dermatitis. This illness was also characterized by fever, lymphadenopathy, pharyngitis, a leukemoid reaction, lymphocytosis, eosinophilia, hepatitis, and noncardiogenic pulmonary edema. Dramatic improvement followed institution of corticosteroid therapy. Studies for infectious and collagen vascular diseases were negative. This severe illness was likely caused by minocycline, and we speculate that minocycline may have acted as a superantigen, causing lymphocyte over-activation and massive cytokine release.

Epstein-Barr virus-associated lymphoproliferative disorder of granular lymphocytes presenting initially as cutaneous vasculitis

Lymphoproliferative disorders of granular lymphocytes (LDGL) represent a family of diseases characterized by persistent granular lymphocytosis with variable prognosis. The Epstein-Barr virus (EBV) has been occasionally linked with the development of LDGL. However, cutaneous manifestations of LDGL have rarely been reported. One patient had cutaneous vasculitis for 10 years before a definite diagnosis of LDGL was made. Chronic EBV infection was documented serologically and EBV DNA was detected in the peripheral blood lymphocytes. EBV RNA was detected in the nuclei of infiltrating lymphoid cells expressing CD43 in a skin biopsy specimen. A cytogenetic study showed clonal chromosomal abnormalities. This is the first report of EBV-associated LDGL of natural killer cells with cutaneous manifestations.

Elevated Le(y) antigen expression on T-lymphocytes in schizophrenic patients

Le(y) is a carbohydrate determinant of membrane glycoconjugates and is expressed in some tumor and embryonic cells. On T lymphocytes, it is known that human immunodeficiency virus (HIV)-infected human lymphocyte T-cell lines express elevated Le(y) antigen and AIDS patients show the highest Le(y) expression in T lymphocytes at lower CD4/CD8 ratio. Later, a comparative elevation of Le(y) expression on T-cell subsets has been noticed to be mainly present in patients with viral diseases, such as acute and chronic hepatitis, implying an association of the highest Le(y) expression with viral infection. We found that Le(y) antigen was most expressed in both CD4+ and CD8+ subsets of peripheral T lymphocytes in hospitalized schizophrenic patients. On the other hand, atypical lymphocytes with stimulated morphology are known to appear in the blood circulation of schizophrenic patients. Similar atypical lymphocytes have also been described in viral and autoimmune diseases. Two possibilities have been discussed: viral association in the pathology in some schizophrenic patients; and immunological abnormalities including environmental effects under hospitalization on immune status, since normal controls (staff in psychiatric hospitals) showed higher Le(y) expression than normal controls under non-psychiatric circumstances.

Epstein-Barr virus: the hematologic and oncologic consequences of virus-host interaction

Varicella-zoster virus (VZV) and Epstein-Barr virus (EBV) are two of the human herpesviruses. The others include herpes simplex virus (HSV) type 1, HSV type 2, and cytomegalovirus (CMV). In a series of two articles, we review the clinical diseases caused by VZV and EBV infections; we pay particular attention to the manifestations of these two viral infections in immunosuppressed and immunocompromised patients. In addition to the clinical reviews, each of the two articles begins with a brief discussion of the molecular aspects of VZV and EBV, respectively; this introduction describes features of the genome and immunogenic viral proteins which have clinical relevance. A model for pathogenesis is included. The first review concerns VZV infections. Recent data about the DNA sequence of the entire VZV genome are included, as well as a review of the VZV glycoproteins. Primary VZV infection (chickenpox) and VZV reactivation (zoster) are described in detail in both healthy individuals and people with cancer. The decade-long VZV vaccine trials in children with leukemia receive special emphasis because they have engendered considerable interest and debate. The second review (published here) covers EBV infections. This virus has been implicated in the causation of a wide variety of human hematological and oncological disorders, besides classical infectious mononucleosis. In particular, Burkitt's lymphoma, nasopharyngeal carcinoma, and lymphoproliferative disorders are strongly associated with EBV infection of the transformed cells. In addition, immunologically mediated cytopenias occasionally follow EBV infection. Finally, treatment regimens with antiviral chemotherapy and other agents are discussed for both VZV and EBV infections.

An immunoperoxidase-autoradiography double labeling method for analysis of lymphocyte activation markers and DNA synthesis

An immunoperoxidase-autoradiography double labeling method for analysis of lymphocyte activation markers and DNA synthesis is described. For this study expression of MHC locus II coded Ia antigen, interleukin-2 receptor, transferrin receptor and gp 40/80 glycoprotein was analyzed using monoclonal antibodies in avidin-biotin-peroxidase complex staining combined with visualization of [3H]thymidine incorporation by autoradiography. Compared to spontaneous [3H]thymidine incorporation assay information is obtained at single cell level. In contrast to blast indexes calculated from MGG stained preparates, information on the expression of various functional cell surface structures as well as DNA synthesis is also obtained. Double-assay for lymphocyte phenotype and DNA synthesis by flow cytometry might be preferred to light microscopy, but the widespread use of immunoperoxidase staining and autoradiography may make this new kind of approach more easily available. Other advantages worth considering are the possibility of transporting, staining and counterstaining as microscope slides and the permanent nature of the documentation and morphological information obtained. In our experience, this method seems to be useful for studying resting peripheral blood lymphocytes as well as mitogen and antigen induced changes in the lymphocyte activation state.

Hypersensitivity to carbamazepine presenting as pseudolymphoma

An unusually severe hypersensitivity reaction to carbamazepine is described, in which the patient presented with lymphadenopathy, hepatosplenomegaly, bone marrow suppression, immunosuppression and other features strongly suggestive of a lymphoma.

Marked atypical lymphocytosis, hepatitis, and skin rash in sulfasalazine drug allergy

A 38-year-old man presented with a generalized pruritic maculopapular rash, fever, myalgias, and edema of the face and neck. Laboratory examination revealed eosinophilia, atypical lymphocytosis, and abnormal liver function results. The clinical course was characterized by rapid resolution after initiation of steroid therapy and withdrawal of sulfasalazine, which had been started three weeks earlier for abdominal cramping and diarrhea. This clinical picture suggests a drug-induced hypersensitivity reaction to a drug commonly used for inflammatory bowel disease, sulfasalazine.

Alterations in plasma membrane lipid organization during lymphocyte differentiation

The fluorescent probe merocyanine 540, which binds preferentially to bilayers in which the lipids are loosely packed, was used to investigate changes in the organization of the lipids of the lymphocyte plasma membrane during primary and secondary lymphopoiesis. When mouse thymocytes were incubated with the dye, most immature cells stained, while most mature cells, about to enter the peripheral circulation, did not. Similarly, mature lymphocytes from both mouse and human peripheral blood did not stain, but these same cells did when activated by in vitro mitogenic stimulation. Freshly isolated splenic lymphocytes, presumably activated in vivo by antigen, also bound merocyanine 540, but after 48 hours of culture in the absence of stimulus they displayed only a low affinity for the dye, a phenotype that reverted to a high affinity upon mitogenic stimulation. These results suggest that changes in the organization of the lipids of the plasma membrane take place during lymphocyte differentiation: viz., immature cells possess a disordered membrane that becomes increasingly ordered as the cells mature and enter the peripheral circulation; then, upon antigen-induced differentiation, the plasma membrane again becomes disordered. These lipid organization changes are discussed in the context of their possible role in the regulation of lymphocyte circulation via intercellular interactions between lymphocytes and cells of the reticuloendothelial system.

Cold-reactive immunoglobulin M antilymphocyte antibodies directed against B cells in Thai children with dengue hemorrhagic fever

Antilymphocyte antibodies were found in 51 of 83 serum specimens from Thai children with dengue hemorrhagic fever (DHF). The lymphocytotoxic activity was complement dependent, and cytotoxicity was detected in the 19S immunoglobulin M-associated serum fractions at a temperature optimum of 15 degrees C. Sera with lymphocytotoxic activity were cytotoxic to autologous as well as allogeneic lymphocytes from patients and healthy adult donors and were directed primarily against B cells, with some T cell cross-reactivity. This study suggests that infection with DHF induces predominately cold-reactive antilymphocyte antibodies in DHF patients that could potentially interact with peripheral blood cells of patients and modulate the humoral immune responses of patients during infection.

T-lymphocyte subpopulations in relation to immunosuppression in measles and varicella

Patients with measles or varicella were studied during the acute phase (first week) of illness and, after recovery, by lymphocyte stimulation tests and determination of T-lymphocyte subpopulations, using the monoclonal antibodies Leu 2a and Leu 3a directed at the suppressor/cytotoxic and the helper T-cell subsets, respectively. Low proliferative responses to phytohemagglutinin were found during the acute phase of both diseases. The response to purified protein derivate of tuberculin was also low in all measles patients tested and in some of the varicella patients. In both infections increased spontaneous DNA synthesis was demonstrated. In the acute phase of measles there was T lymphocytopenia but no change of the ratio between T lymphocytes of helper and suppressor/cytotoxic cell phenotypes. In the acute phase of varicella the percentage and the absolute number of Leu 2-positive (suppressor/cytotoxic) T cells were increased. Measurement of the size of the lymphocytes indicated activation of this subset. Cryopreserved blood mononuclear cells from the acute phase of varicella could suppress the phytohemagglutinin response of autologous convalescent-phase cells. This was not seen when cells from measles patients were tested. The suppression of the lymphocyte stimulation response in varicella is probably in part caused by activation of suppressor cells, whereas the suppression of the stimulation response in measles seems to be due mainly to other mechanisms.

Spontaneous proliferation of cerebrospinal fluid mononuclear cells in multiple sclerosis. A longitudinal study

Cerebrospinal fluid (CSF) and peripheral blood (PB) specimens from 32 MS patients longitudinally followed for up to 24 months and from a group of control patients without intrathecal inflammation were studied for the occurrence of activated lymphocytes with an autoradiography method. MS patients had higher numbers of proliferating mononuclear cells in CSF than did the controls, both during remission and exacerbation phases, whereas this difference was not found in the PB. ACTH treatment decreased the number of proliferating cells in CSF but had no effect on those of the PB of MS patients. A large variation in spontaneous proliferation of CSF cells was evident during the follow-up of individual patients, and there seemed to be no uniform correlation to the clinical fluctuations.

Haematological alterations in acute malaria

In a study of 30 patients with either Plasmodium or falciparum infection, 29 (97%) showed the presence of atypical lymphocytes in the peripheral blood film, 24 (80%) had thrombocytopenia and 17 (57%) had a mild to moderate anaemia. Bleeding was encountered in 2 patients without confirmatory evidence of disseminated intravascular coagulation.

Immunological and virological investigations in Down's syndrome

Lymphocyte responsiveness to phytohaemagglutinin and viral antigens was studied in children with Down's syndrome and in controls. Mitogen-responsiveness in the patients was significantly reduced as compared to the control values. Using the lymphocyte transformation test, trisomic patients showed more than a twofold increase in sensitivity to herpes simplex virus as compared to controls. The same test did not show any essential difference between the two groups when adeno- and influenza viruses were used. Immunofluorescence technique, with specifically conjugated antiviral sera, permitted the detection of specific fluorescence in 30% of the patients with Down's syndrome indicating the presence of oncogenic adenovirus type 12 antigen in the circulating lymphocytes. No antibodies--or only very low titres--against adeno- and herpes simplex viruses were demonstrated in the sera of trisomic patients. Mononuclear leukocytes from these patients often showed structural alterations. The incidence of infectious herpes simplex virus and Candida albicans in the saliva of patients was higher than in the control group. It seems that Down's syndrome involves partial disturbance of both the cellular and humoral immune functions--at least with respect to certain viral antigens.

Atypical lymphocytosis in children

A complete blood count performed during the evaluation of a febrile or traumatized child may show the presence of atypical lymphocytosis. Although atypical lymphocytes occur in several conditions, they are most closely associated with infectious mononucleosis (IM). We initiated a study to determine if the presence in children of atypical lymphocytosis without the triad of splenomegaly, pharyngitis, and adenopathy is a manifestation of IM. Heterophil antibody (HA) and Epstein-Barr virus (EBV) titers were performed on 45 children with greater than or equal to 5% atypical lymphocytes. None had a significant HA titer. Thirty-three were seronegative for EBV, and 11 had titers indicative of past infection. One child had an antibody pattern suggesting a recent EBV infection; none had a titer consistent with acute IM. We conclude that isolated atypical lymphocytes does not point to infectious mononucleosis.

Primary Epstein-Barr virus infection in early childhood

In a prospective study 43 consecutive children in hospital, aged between 6 months and 7 years and displaying at least one of the clinical signs of infectious mononucleosis (IM), were investigated for Epstein-Barr (EB) virus-specific IgM antibodies by an indirect immunofluorescence test. On this basis EB virus infection was considered confirmed in 8 patients, each of whom had IgM antibodies in the initial serum sample. In one additional patient, IgM antibodies were only detected in a second sample. The IgM antibodies disappeared with 3-11 weeks. Assessment of IgG antibodies had no diagnostic value in the acute phase of IM. Clinically the 3 youngest children, about 1 year of age, were diagnosed as having pneumonia or hepatitis, the 5 other consecutive patients as having IM. Hepatosplenomegaly was fairly frequently associated with IM, while sore throat, lymphadenopathy, and rash were often signs of other diseases. Only the oldest child had heterophil antibodies. Atypical lymphocytes (greater than 10%) were present in 4 of the 9 IM cases and were seen in children with other diseases as well. Our data stress the importance of measuring EB virus-specific IgM antibodies in order to diagnose IM in early childhood.

Lymphocyte blast transformation responses in measles infection

Lymphocyte blast transformation responses were studied in eight patients with natural measles infection. A specific response to purified measles virus antigen and a weaker response to crude measles virus antigen were found after infection. The response to purified measles antigen appeared 1-3 weeks after the beginning of the rash, when the great number of proliferating mononuclear cells found in the peripheral blood during the rash was declining. In the first weeks after onset of the rash also leucocyte and lymphocyte numbers were decreased, and specific responses to purified tuberculin (PPD) and to rubella and mumps virus antigens were suppressed. In mitogen stimulation tests there was no significant suppression of phytohaemagglutinin and concanavalin responses in this small series, but the response to pokeweed mitogen was decreased. The responses to antigens other than measles virus antigens recovered in parallel with the increase of the measles-specific response.

Pseudohyperkalaemia and infectious mononucleosis

Pseudohyperkalaemia is described from a patient with infectious mononucleosis. The in vitro release of potassium was associated with clotting and all the blood cells may have been involved.

Kinetics of peripheral blood leukocyte alterations in Thai children with dengue hemorrhagic fever

Peripheral leukocytes from 16 Thai children with dengue hemorrhagic fever were examined to determine the leukocyte composition on the day of presentation and on convalescent days 15 and 30. Mononuclear cells were isolated each time, and the concentrations of T, B, Fc receptor-bearing, and "null" cells were determined. On the day of hospitalization, in comparison to convalescent values, there was a significant increase in total lymphocytes, primarily due to concentrations of atypical lymphocytes. There was a significant loss of T cells with an increase in non-T, non-B, non-Fc receptor-bearing null cells. There were no changes in the concentrations of monocytes, B cells, or Fc receptor-bearing cells when acute and convalescent values were compared. During the convalescent period, a progressive increase in eosinophils was noted. Also, on day 15 but not on day 30 of the convalescent period, an increase was observed in the total leukocyte number due to an increase in granulocytes. There results indicate that in Thai children with dengue hemorrhagic fever, there are major shifts within several component cell subpopulations of the immune system.

Lymphocyte density distribution profile and spontaneous transformation related to the stage of Hodgkin's disease

Density distribution profiles of peripheral lymphocytes were made in 41 untreated patients with Hodgkin's disease and in 14 normal controls. The fraction of lymphocytes with a low specific gravity in patients was significantly increased in comparison to normal controls (P=0.0007). These low density lymphocytes in Hodgkin's disease patients showed an elevated spontaneous 3H-thymidine incorporation compared to normal controls (P less than 0.0001). In 78% of the patients the spontaneous DNA synthesis of the low density lymphocytes was above the normal range. A positive correlation (P=0.002) was found between the spontaneous 3H-thymidine uptake and the stage of the disease.

The lymphoid leukocytoses

The experienced morphologist can be extremely helpful to the clinician by virtue of his or her ability to distinguish among the various subtypes of reactive lymphocytoses. An awareness on the part of the clinician as to the nuances of subclassification may lead to earlier diagnosis of a disease process. Broadly, proliferations of normal lymphocytes point to infectious lymphocytosis or Bordetella pertussis infection. Proliferations of atypical lymphocytes, especially when minimum diagnostic criteria are present or there are four or more Downey III forms per 100 WBCs, suggest infectious mononucleosis. Proliferations of immunoblasts reflect hypersensitivity reactions to drugs or autoimmune disease. Proliferations of proplasmacytes or plasma cells favor viral hepatitis, drug reactions (notably to sulfa drugs), or rubella. Quantitative data may help refine the morphologic implications. Cumulatively, qualitative and quantitative data should lead the clinician to a judicious selection of confirmatory serologic tests and hence to earlier diagnosis.

The circulating "atypical" lymphocyte

Atypical lymphocytes have been observed in the peripheral blood of patients in a large number of clinical situations, including immune reactions to transplantation and immunization, collagen diseases and other autoimmune disorders, malignant disease, drug reactions, and infectious mononucleosis, as well as other bacterial and viral infections. These cells are readily identified by their increased size and the presence of active DNA synthesis. In morphology, they closely resemble lymphocytes transformed into blasts by exposure to mitogens or antigens in vitro. They vary in morphologic detail as well as surface marker characteristics, indicating that they comprise a heterogeneous mixture of cell types. These data suggest that atypical lymphocytes may represent a polyclonal immune response to antigenic stimulation.

Proliferating cells in demyelinating states

Proliferation of mononuclear cells was examined with an autoradiography method in the CSF and peripheral blood of 13 patients with multiple sclerosis (MS), serially during activation of disease in one patient with subacute sclerosis panencephalitis (SSPE), and in some control patients with various neurological conditions. High cerebrospinal fluid (CSF) cell labelling indices, up to 1.7%, which could not be directly related to the clinical activity of the disease, were found in some MS patients. During activation of SSPE there was marked increase in labelled cells of CSF, up to 4.3%. In controls, corresponding CSF indices ranged from less than 0.1% to 0.4%. Mononuclear cells in CSF and peripheral blood behaved as clearly different cell populations.

Human lymphocyte culture: intrinsic factors influencing the quality of chromosome preparations

In a cytogenetic study of the consecutive cell cycles (M1, M2 etc.) from human lymphocyte cultures after 5-bromodeoxyuridine incorporation followed by differential Giemsa staining, the metaphases of M2 and subsequent in vitro divisions have been found to spread better than those of M1 cells, as if the cells of in vitro generation suffer some membrane alterations. Moreover presence of S or G2 phase, leukocytes in a blood sample may result into early proliferation in a PHA stimulated culture system, so that the metaphase yield at 72 h will be larger than otherwise, a sizeable portion of which, being in M2 or subsequent cell cycles, will spread better. Thus such individual or transient intrinsic factors of haematologic state may influence the success of a leukocyte culture and the quality of chromosome preparation.

Hyperbasophilic immunoblasts in circulating blood in chronic inflammatory rheumatic and collagen diseases

The number of large circulating hyperbasophilic mononuclear cells - referred to as hyperbasophilic immunoblasts (HBI)- is often increased in collagen disease and rheumatoid arthritis (RA) and grossly reflects the degree of disease activity. In contrast, in psoriatic arthropathy the percentage of (HBI) is within the normal range. HBI are mainly involved in immune reactions and may provide a valuable routine test for the assessment of the latter in disease states and for the predicition of relapse in chronic collagen diseases. Immunofluorescent techniques applied to samples from active autoimmune diseases have shown that a number of HBI are Ig-producing B-blasts. Moreover, in a few cases these intracytoplasmic immunoglobulins exhibited a rheumatoid factor-like activity, a finding which promises to yield additional information on the immunopathogenesis of RA.

False positive infectious mononucleosis serology in epilepsy

Positive serum tests for infectious mononucleosis (IM) unaccompanied by the clinical syndrome or blood changes characteristic of the disease were detected in 39/177 (22%) mentally subnormal patients investigated with three different commercially available IM slide tests. Slide positively was still detectable six months later in 27/35 (77%) positive reactors. Positive IM slide tests were significantly associated with anticonvulsant, primarily phenobarbitone therapy and with concomitant elevations of immunoglobulins IgG and IgM. Epstein Barr virus antibodies were not detectable in the sera of 8/38 (21%) positive slide reactors. The implications of these observations are discussed and attention is drawn to the variations in sensitivity, specificity, and comparability of different IM slide tests.