Immunoglobulin production by human lymphocytes in a microculture system: culture conditions and cellular interactions

Clinical, microbiological and host defense parameters associated with a case of localized prepubertal periodontitis

A 4-year-old Japanese boy was referred to Osaka University Dental Hospital because of severe mobility and pain of the right lower primary canine. The canine had severe bone loss and a pocket depth exceeding 5-6 mm. The left lower canine showed slight mobility and moderate alveolar bone loss. The other primary teeth showed no pathogenic findings. The subgingival microflora from the right lower canine was dominated by gram-negative rods, especially capnocytophaga and fusobacterium, while actinomyces sp. were the most common gram-positive bacteria. While neutrophil functions of the patient were within the normal ranges of healthy subjects, some lymphocyte functions such as IL-2 production and IgG and IgM syntheses were lower in the patient. 7 months after the extraction of the right lower primary canine, the patient complained of pain around the right lower primary lateral incisor. In 3-4 weeks, the alveolar bone was lost rapidly and mobility of the lower anterior teeth increased significantly. The primary lateral incisor was extracted and the other primary teeth were treated by sealing and systemic and local administration of antibiotics. After treatment, the lower anterior teeth became less mobile and the gram-positive cocci predominated.

Anti-CD27 monoclonal antibodies identify two functionally distinct subpopulations within the CD4+ T cell subset

Anti-CD27 monoclonal antibodies react with a cell surface molecule expressed on medullary thymocytes and a large subpopulation (75%) of peripheral blood T lymphocytes. This study was undertaken to analyze the functional capacities of CD27+ and CD27- subpopulations within the CD4+ subset. In addition, we investigated whether CD27 subpopulations belong to two mutually exclusive T cell sublineages. Proliferation upon lectin stimulation by either phytohemagglutinin or pokeweed mitogen (PWM) was found to be consistently higher in CD4+CD27+ cells compared to CD4+CD27- cells. In contrast, CD27+ and CD27- cells did not differ in anti-CD3, soluble antigen or interleukin (IL)2-induced proliferation. In PWM-driven B cell differentiation, CD4+CD27+ cells provided helper activity on IgM production, while CD4+CD27- cells did not. The differences observed between CD4+CD27+ and CD4+CD27- cells in both proliferation and T helper activity on IgM production can, at least in part, be explained by the inadequate production of IL2 by CD27- cells upon lectin stimulation. In contrast, CD27+ and CD27- subpopulations did not differ in the production of interferon-gamma. CD27- cells could be induced to express the CD27 antigen through stimulation of these cells with immobilized anti-CD3 antibodies. After 3 days of culture, approximately 50% of the cells had CD27 membrane expression, whereas after 6 days 80% of the cells express the antigen. We conclude that anti-CD27 antibodies identify two functionally distinct T cell populations within the CD4+ subset. These subpopulations apparently do not belong to two separate T cell sublineages, but may reflect differences in the activation state of CD27+ vs. CD27- peripheral blood T lymphocytes.

T cells in patients with chronic T gamma lymphocytosis: morphology, cytochemistry, ultrastructure and immunological characteristics

We have studied the morphology and cytochemistry in relation to the immunological phenotyping and functional properties of T cells from eight patients with chronic T gamma lymphocytosis. At the light microscopic level the morphology of the patients' lymphocytes was similar to that described for large granular lymphocytes. Ultrastructurally, a division into two groups could be made on differences in the amount of cytoplasm and the location and the more irregular form of the nuclei. The lymphocytes of one group (five patients) had in common the phenotype Fc gamma +, T3 +, T4 -, T8 +, Ia -, M1 - and demonstrated (with the exception of one patient) the same functions: presence of K-cell activity, absence of NK, helper and suppressor cell activities. In the other group (three patients), the lymphocytes of one patient showed the same phenotype and functions as those indicated above. The other two patients both lacked the T8 antigen on their lymphocytes but were different with regard to other surface markers. In addition, their cells were functionally identical: both demonstrated NK- and K-cell activity. Thus in this group of eight patients with chronic T gamma lymphocytosis, the immunological and functional subdivision paralleled in part a morphological division at the ultrastructural level.

Induction of immunoglobulin synthesis by interleukin 2 is T4+/T8- cell dependent. A role for interleukin 2 in the pokeweed mitogen-driven system

The role of interleukin 2 (IL2) in the induction of human B cell differentiation in vitro was studied. IL2 was unable to induce immunoglobulin (Ig) production in non-T cells either in the presence or absence of pokeweed mitogen (PWM). However, IL2 alone could induce Ig production in non-T cells when irradiated T cells were present. Similar to the PWM-driven system helper activity was delivered by T4+ but not T8+ cells. Apparently, IL2 acts on T4+ cells and induces these cells to deliver the actual helper signal(s) for Ig production by B cells. Whereas in the PWM-driven system only T8+ cells suppress Ig synthesis, IL2-driven Ig synthesis was suppressed by both T4+ and T8+ cells added to a mixture of non-T cells and irradiated T4+ cells. This suppressor activity could be abrogated by irradiation. PWM was shown to induce IL2 production in both T4+ and T8+ cells. Moreover, PWM-induced Ig synthesis, like IL2-induced Ig synthesis, could be totally abrogated by a monoclonal antibody against the human IL2 receptor (anti-Tac). These findings, coupled to the innate Ig-inducing capacity of IL2, indicate a role for IL2 in the PWM-driven system. The mechanism of suppression in both the PWM- and the IL2-driven systems was not shortage of IL2 in the culture due to consumption or inhibition of production of IL2. Moreover, the T8+ cells produced IL2, despite their failure to help Ig synthesis. Helper T cell activity can thus be divided into two distinct activities: IL2 production and the ability to deliver the actual helper signal such as helper factors for B cell differentiation. This insight allows a better evaluation of the immunoregulatory activities of T cell subsets in health and disease.

Regulatory activity of neoplastic T cells in Sezary syndrome on in vitro immunoglobulin production

Functional activities and surface markers of the neoplastic T cells of three patients with Sézary syndrome were studied and compared with the functional activities of OKT4+ and OKT8+ T-cell subsets from healthy donors. The neoplastic T cells of the patients had the following marker phenotype: OKT1+3+4+6-8-11+17+I1-M1-3A1-. In contrast to healthy donor OKT4+ T cells, none of the neoplastic T cells had significant helper activity on pokeweed-mitogen-driven Ig synthesis. In one patient the neoplastic T cells suppressed pokeweed-mitogen-driven Ig synthesis. The suppression by the patient cells did not require the presence of radiosensitive OKT4+ suppressor-inducer cells in the culture. It is concluded that OKT4+8-3A1- neoplastic T cells from Sézary-syndrome patients lacking helper activity are more common than previously thought and that in some cases the OKT4+8-3A1- Sézary cells can mediate suppressor activity.

Polyclonal activation of human peripheral blood B lymphocytes by Fusobacterium nucleatum

The present study examined in vitro polyclonal human B-lymphocyte (B-cell) activation (PBA) by Fusobacterium nucleatum. Pokeweed mitogen, a well-studied PBA activator, was included in some experiments for comparison. PBA was determined by the total immunoglobulin A, G, and M concentrations in the culture supernatants as measured by micro-enzyme-linked immunosorbent assay. F. nucleatum, at concentrations between 1 and 10 micrograms/ml, stimulated optimal PBA in monocyte-depleted cultures, whereas the pokeweed mitogen response was optimal in unfractionated, monocyte-containing cultures. Immunoglobulin synthesis occurred primarily between days 6 and 8 after stimulation with F. nucleatum. T lymphocytes enhanced the PBA response to F. nucleatum, particularly at a T- to B-cell ratio of 1:1. Immunoglobulin production was greater in round-bottomed wells than in flat-bottomed wells at lymphocyte concentrations of 200,000 cells per well. The PBA response, however, increased dramatically in flat-bottomed wells containing higher lymphocyte concentrations, suggesting that PBA is enhanced by cell-to-cell contact. A delay in stimulation of the lymphocytes with F. nucleatum resulted in diminished immunoglobulin production. The results provide information on the regulation of in vitro PBA induced by F. nucleatum. The data also suggest that there may be differences in the mechanisms by which F. nucleatum and pokeweed mitogen stimulate PBA.