SARS-CoV-2 seropositivity amongst healthcare workers in South Africa during the Omicron wave: natural infection versus vaccination.

Aims: Concerns over population-level immunity have been heightened with each successive wave of COVID-19, prompting questions about whether it is primarily derived from vaccination efforts or from previous natural infections with the virus. We wished to determine the seroprevalence of SARS-CoV-2 antibodies among healthcare workers (HCWs) in Pretoria (Tshwane), South Africa, and to establish whether they were derived from vaccination or natural infection.

Methods: Serum samples were collected from HCWs during the fourth wave of COVID-19 between 1 December 2021 and 13 March 2022.

Dataset of cell viability and analytes released by cancer cell lines exposed to low pH and conditioned medium.

Cancer cells influence their microenvironment by secreting factors that promote tumour growth and survival while evading immune-mediated destruction. We previously determined the expression of secreted factors in breast and oesophageal squamous cell carcinoma cell lines (MCF-7 and WHCO6, respectively) using Luminex assays. These cells were subsequently treated with low pH medium to mimic acid exposure, and the effects on cell viability, proliferation, and secretion of cytokines, chemokines and growth factors were described [1].

The effect of acute acid exposure on immunomodulatory protein secretion, cell survival, and cell cycle progression in tumour cell lines.

Cancer develops when multiple systems fail to suppress uncontrolled cell proliferation. Breast cancers and oesophageal squamous cell carcinoma (OSCC) are common cancers prone to genetic instability. They typically occur in acidic microenvironments which impacts on cell proliferation, apoptosis, and their influence on surrounding cells to support tumour growth and immune evasion.

Inducing apoptosis using chemical treatment and acidic pH, and detecting it using the Annexin V flow cytometric assay.

Cell death is important in physiology, and can happen as a result of structural damage, or as a sequence of programmed cellular processes known as apoptosis. Pathogenic alterations in apoptosis occur in a number of diseases, including cancer, viral infections, autoimmune diseases, immunodeficiencies, and degenerative conditions. Developing accurate and reproducible laboratory methods for inducing and detecting apoptosis is vital for research into these conditions.

The acidic tumour microenvironment: Manipulating the immune response to elicit escape.

The success of cancer treatment relies on the composition of the tumour microenvironment which is comprised of tumour cells, blood vessels, stromal cells, immune cells, and extracellular matrix components. Barriers to effective cancer treatment need to be overcome, and the acidic microenvironment of the tumour provides a key target for treatment. This review intends to provide an overview of the effects that low extracellular pH has on components of the tumour microenvironment and how they contribute to immune escape.

Patients Awaiting Renal Transplantation in South Africa: The Need for Highly Sensitive Laboratory Testing and Immunological Risk Stratification.

Background: Suitable laboratory testing prior to transplantation ensures that a patient's immunological risk is understood and allows the transplantation team to make the correct decisions on donor-recipient pairing. Preformed donor-specific anti-HLA antibodies mediate rejection in transplanted patients. Improved laboratory testing is needed to increase the chances of successful organ allocation.

Luminex-based virtual crossmatching for renal transplantation in South Africa.

Background: Current practice in the Johannesburg renal transplantation programme is to perform a transplant when the patient's complement-dependent cytotoxicity and flow cytometric crossmatches are negative. However, even in patients with negative crossmatches early graft rejections have occurred. We retrospectively evaluated the use of Luminex anti-human leukocyte antigen (HLA) antibody detection technology, often termed 'virtual crossmatching', compared with the flow cytometric crossmatch, for predicting graft outcome in renal transplant patients.

Multi-analyte profiling of ten cytokines in South African HIV-infected patients with Immune Reconstitution Inflammatory Syndrome (IRIS).

Background: Immune reconstitution inflammatory syndrome (IRIS) is an important complication of HAART in sub-Saharan Africa, where opportunistic infections (OIs) including mycobacteria and cryptococcus are common. The immune system's role in HIV infected patients is complex with cytokine expression strongly influencing HIV infection and replication.

Methods: We determined the expression patterns of 10 cytokines by Luminex multi-analyte profiling in 17 IRIS nested case-control pairs participating in a prospective South African cohort initiating anti-retroviral therapy.