Integrated measurements by flow cytometry of the cytokines IL-2, IFN-gamma, IL-12, TNF-alpha and functional evaluation of their receptors in human blood

Novel mutations in the exon 5, intron 2 and 3' UTR regions of IL-12B gene were observed in clinically proven tuberculosis patients of south India

Interleukin-12 (IL-12) is formed by the interaction of IL-12p35 and IL-12p40 expressed independently from IL-12A and IL-12B genes. This interleukin plays prominent role in the T-helper type-1 (Th1) response against intracellular pathogens. Variations in IL-12B gene causes disruption of various activities one of them is suppression of Th1 response and is one of the characteristic features observed in patients with active tuberculosis. Hence, in the present study IL-12B gene status was evaluated in 50 new sputum smear-positive pulmonary tuberculosis patients (NSP-PTB) as identified by Ziehl-Nielsen (ZN) staining and 50 apparently healthy control subjects (HCS) who were sputum smear-negative. The sequence analysis showed novel missense mutations p.Ser205Ile, p.Leu206Glu, p.Pro207Ser, p.Glu209Lys, p.Val210Ser, p.(Ser205_Cys327delinsIleGlu) and p.(Lys217_Leu218delinsIle) were found in exon 5 of the IL-12B gene in nine patients resulting formation of inactive IL-12 and three patients showed novel frame shift mutations p.(Asn222Leufs∗23) in exon 5 of causing the formation of truncated protein. Several mutations were noted in intron 2 of the IL-12B gene in 5 patients and in 13 patients mutations were observed in 3' UTR region. All together 30/50 patients (60%) showed mutations in IL-12B gene. Decreased levels of interferon-gamma (IFN-γ) and IL-12 as determined by ELISA and flow cytometry were observed in the peripheral blood mononuclear cell culture supernatants in TB patients having mutations compared with control subjects. Further, in silico analysis revealed due to frame shift mutations in exon 5 at Asn222 resulted in deletion of functional fibronectin type-III (FN3) domain which leads to formation of inactive IL-12 in these patients.

Expression and in vitro upregulation of MHCII in koala lymphocytes

Understanding and measuring immune activity of the koala (Phascolarctos cinereus), is important to studies of the epidemiology and impact of the widespread chlamydial and koala retroviral (KoRV) infections that occur in this iconic but increasingly threatened species. To explore the interaction of disease and immunity, and to assess the potential for use of class II major histocompatibility complex (MHCII) upregulation as an indicator of lymphocyte activation in in vitro immune assays, we have investigated the expression of MHCII in koala lymphocytes by flow cytometry. MHCII expression was upregulated in mitogen stimulated B lymphocytes in vitro but no such increase was detected in vivo in free-living koalas with active inflammation. In assessing phenotypic baseline data of captive koalas, we have identified that MHCII is expressed predominantly on circulating B lymphocytes (85.7 ± 2.4%) but on very few T lymphocytes (3.4 ± 1.9%), even following activation, and suggest that the latter finding might be compensated by the greater absolute numbers of peripheral blood B lymphocytes in this species relative to many eutherian species.

Interferon-gamma receptors in HIV-1 infection

We studied in vitro production of interferon-gamma and expression of interferon-gamma receptors (R1 and R2) by the peripheral blood mononuclear cells of 24 HIV-1-infected patients and 12 healthy volunteers. Interferon-gamma production was lower in HIV-1-infected patients compared with healthy volunteers (p < 0.05), and it further declined in patients with lower CD4+ T-cell counts. In contrast, expression of interferon-gamma R1 by CD4+ T lymphocytes was higher in HIV-infected patients than healthy volunteers (25% versus 10%, p < 0.05). In the HIV-infected group, interferon-gamma R1 expression increased with a decline in CD4+ T-cell count (r = -0.64, p < 0.001). Interferon-gamma R2 expression directly correlated with interferon-gamma R1 expression (p < 0.001). When stimulated with heat-killed Mycobacterium avium complex (MAC) and phorbol myristic acetate (PMA), the mononuclear cells of patients with advanced HIV-1 infection had lowered ability to produce additional interferon-gamma (either MAC or PMA) and interferon-gamma receptors (MAC). In conclusion, with progression of HIV-1 infection, interferon-gamma production declines whereas expression of interferon-gamma receptors (R1 and R2) increases. Persistent upregulation of both interferon-gamma R1 and R2 receptors probably favors development of type 2 T-helper cells environment and promotes viral replication. This dysfunction in the interferon-gamma pathway contributes to a further impairment in cellular immune function in patients with advanced HIV-1 infection, which may further increase susceptibility to opportunistic infections.

Severe combined immunodeficiency syndrome associated with colonic stenosis

BACKGROUND

This is the first report in Mexico of a case of severe combined immunodeficiency syndrome (SCID) associated with colonic stenosis. The patient was an 8-month-old Mexican female who died at this age. She suffered infections due to microorganisms such as Mycobacterium tuberculosis, bacille Calmette-Guérin (BCG), Candida sp., and Pneumocystis carinii; and had frequent diarrhea. She was HIV-negative without familial history of immunodeficiency. The aim of the work was to analyze the immunologic status of this patient.

METHODS

Peripheral blood from the patient and from a healthy matched control were analyzed by flow cytometry to determine peripheral leukocytes and production of cytokines and their receptors in T-lymphocytes and monocytes. Immunohistochemical analysis was performed in spleen and lymph node sections from the patient and control samples to assess alterations in architectural and cellular distribution within these lymphoid tissues.

RESULTS

Peripheral blood analysis demonstrated reduced numbers of both T and B cells and defective expression of cytokines by activated T cells. Postmortem analysis revealed very small T and B cell zones in spleen and lymph nodes, absence of germinal centers and follicular dendritic cell networks, and two zones of stenosis at level of colon sigmoides.

CONCLUSIONS

As a whole, these data are consistent with severe combined immunodeficiency (SCID) syndrome; thus, we conclude that this patient may have had a variant of SCID syndrome associated with intestinal stenosis.