Distinct effect of forskolin and interferon-gamma on cell proliferation and regulation of histocompatibility antigen expression in hematopoietic cells.

The adenylate cyclase activator, forskolin, was found to induce expression of class I and class II major histocompatibility complex antigens in a B precursor cell line, Reh, as well as in a B lymphoid cell line, Raji. No such effect was, however, observed when the promyelocytic cells line HL-60 was treated with either forskolin or the cAMP analogue 8-bromoadenosine cyclic monophosphate. As expected, all three cell lines showed reduced proliferation upon forskolin treatment. Forskolin induced expression of class I and class II major histocompatibility complex antigens in cell lines not affected by interferon-gamma and vice versa, indicating that cAMP is not involved in the regulation of histocompatibility antigens by interferon-gamma. We also compared the effect of interferon-gamma and 12-O-tetradecanoylphorbol 13-acetate on major histocompatibility complex class I and class II expression, and despite differences in the response on the tested cell lines, we can not at this point exclude the possibility that protein kinase C is involved in the action of interferon-gamma.

The role of interleukin-2 (IL-2) in the specific unresponsiveness of lepromatous leprosy to Mycobacterium leprae: studies in vitro and in vivo.

The role of IL-2 in the immunological deficiency of lepromatous leprosy patients towards Mycobacterium leprae have been studied further. After initial stimulation with M. leprae + IL-2, lepromatous lymphocytes could be restimulated with M. leprae alone. The specificity of the responses obtained varied. Some patients gave a stronger response to BCG as compared to M. leprae, while in others a stronger response to M. leprae as compared to BCG was obtained. Studies of the composition of lymphocytes in dermal infiltrates subsequent to injection of killed M. leprae revealed that in both tuberculoid and lepromatous patients, early accumulation of cell staining for both IL-2 receptor and IL-2 were seen. However, with time IL-2 receptor and IL-2 staining lymphocytes diminished in lepromatous infiltrates, while these were maintained in tuberculoid lesions.

Specific chromosome markers involved with chronic T lymphocyte tumors.

In a series of 12 patients with chronic T cell tumors, 9 showed abnormalities of the long arm of chromosome #14. The most common aberration was an inversion with breakpoints in q11 and q32, which was seen in 7 patients. One patient had a translocation between chromosomes #9 and #14, with breaks in 9q34 and 14q11, and in another patient, the two long arms of chromosome #14 were fused together in q32, forming a dicentric chromosome. The results confirm earlier suggestions that rearrangements of band 14q11 are involved with T cell tumors and may be of importance for the development of the disease. Chromosome #8 aberrations were seen in seven patients, six of whom had an extra 8q in common. Abnormalities of chromosome #7 occurred in five patients, but the breaks were localized in different bands. The significance of the karyotypic changes in our present and previous series of patients is discussed, together with data from other laboratories.

A microassay for quantitatively detecting the Epstein-Barr virus receptor on single cells utilizing flow cytometry.

A quantitative microassay for detecting and analyzing the Epstein-Barr virus receptor (EBVR) utilizing fluorescein-conjugated virions is presented. The test is virus substrain-specific. Both the B95-8 and P3HR-1 strains were labelled and adsorbed to a variety of targets. Relative binding of virus was assessed by flow cytometry, the results being directly comparable with those obtained by earlier methods. Cell size and cellular DNA content were measured simultaneously with virus binding, thus enabling us to calculate EBVR density and to correlate receptor synthesis and cell cycle stage.

Mycobacterium leprae reactive T cell clones from lepromatous leprosy patients after prolonged dapsone chemotherapy.

The proliferative responses of peripheral blood mononuclear cells (PBMC) to Mycobacterium leprae and BCG were studied in two groups of leprosy patients: a group of 8 lepromatous patients who had been on treatment for more than 20 years (TLL) and a group of 8 untreated lepromatous leprosy patients (ULL). The mean response to M. leprae of the TLL group was 6195 cpm with 5 of the 8 patients responding positively. The mean response to M. leprae of the ULL group was 617 cpm, with only 1 patient showing a positive response. The corresponding proliferative responses to BCG were 19,908 cpm in the TLL group and 7908 in the ULL group. Thirteen M. leprae reactive clones were established from 2 TLL patients and 5 M. leprae reactive clones were established from 2 tuberculoid leprosy patients. Seven of these clones, 4 from the TLL patients and 3 from the tuberculoid (TT) patients could be studied further. Three of the TLL clones responded specifically to M. leprae, while one of the clones exhibited a broad cross-reactivity to other mycobacteria. All of these clones were of the CD4+CD8- phenotype. Our findings suggest that responsiveness to M. leprae can be detected in vitro in a proportion of LL patients who have undergone prolonged chemotherapy, and that this response involves M. leprae reactive CD8+CD8- T cells, of which some appear to be specific to M. leprae.

A preliminary note on the composition of lymphocytes in human peripheral lymph.

Pilot experiments on the composition of lymphocytes in human peripheral lymph, mainly from healthy human volunteers, are presented. The experiments undertaken so far show a reduced proportion of B cells and an increased proportion of "Ia" positive lymphocytes in peripheral lymph as compared to peripheral blood. If confirmed, these data would suggest that lymphocyte circulation through extravascular subcutaneous tissues is a highly selective process.