The effect of immunization with inactivated SARS-CoV-2 vaccine (CoronaVac) and/or SARS-CoV-2 infection on antibody levels, plasmablasts, long-lived-plasma-cells, and IFN-γ release by natural killer cells

OBJECTIVES

We evaluated the antibody response, natural killer cell response and B cell phenotypes in healthcare workers (HCW) who are vaccinated with two doses of CoronaVac with or without documented SARS-CoV-2 infection and unvaccinated HCWs with SARS-CoV-2 infection.

METHODS

HCWs were divided into four groups: vaccine only (VO), vaccine after SARS-CoV-2 infection (VAI), SARS-CoV-2 infection only (IO), and SARS-CoV-2 infection after vaccine (IAV). Anti-SARS-CoV-2 spike protein (Anti-S) antibodies were measured by Elecsys Anti-SARS-CoV-2 S ELISA kit. Memory B cells (CD19⁺CD27⁺), plasmablast B cells (CD19⁺CD138⁺) and long-lived plasma cells (LLPC; CD138⁺CD19^-) were measured by flow cytometry in 74 patients. Interferon gamma (IFN-γ) release by natural killer (NK) cells were measured by NKVue Test (NKMAX, Republic of Korea) in 76 patients. RT-PCR was performed with Bio-speedy® COVID-19 qPCR detection kit, Version 2 (Bioexen LTD, Istanbul, Turkey).

RESULTS

The Anti-S antibodies were detectable in all HCWs (n: 224). The median Anti-S titers (BAU/mL) was significantly higher in VAI (620 25-75% 373-1341) compared to VO (136, 25-75% 85-283) and IO (111, 25-75% 54-413, p < 0.01). VAI group had significantly lower percentage of plasmablasts (2.9; 0-8.7) compared to VO (6.8; 3.5-12.0) and IO (9.9; 4.7-47.5, p < 0.01) (n:74). Percentage of LLPCs in groups VO, VAI and IO was similar. There was no difference of IFN-γ levels between the study groups (n: 76).

CONCLUSION

The antibody response was similar between uninfected vaccinated HCWs and unvaccinated HCWs who had natural infection. HCWs who had two doses of CoronaVac either before or after the natural SARS-CoV-2 infection elicited significantly higher antibody responses compared to uninfected vaccinated HCWs. The lower percentages of plasmablasts in the VAI group may indicate their migration to lymph nodes and initiation of the germinal center reaction phase. IFN-γ response did not differ among the groups.

Killer cell immunoglobulin-like receptor genotypes in the Turkish population

One hundred eighty-seven healthy and unrelated volunteers from various regions of Turkey were selected for the study. Killer-cell immunoglobulin-like receptors (KIR) genotyping was performed by polymerase chain reaction using commercial sequence-specific oligonucleotide probe (SSOP) kits. Gene frequencies of the Turkish population were determined by direct counting of the positive and negative loci. The genotype data is publicly available in the Allele Frequencies Net Database under the population name "Turkey KIR pop 3" number "3399".

Effects of Malnutrition on Neutrophil/Mononuclear Cell Apoptotic Functions in Children with Acute Lymphoblastic Leukemia

BACKGROUND

Recent studies claim that apoptosis may explain immune dysfunction observed in malnutrition.

OBJECTIVE

The objective of this study was to determine the effect of malnutrition on apoptotic functions of phagocytic cells in acute lymphoblastic leukemia (ALL).

MATERIALS AND METHODS

Twenty-eight ALL patients (13 with malnutrition) and thirty controls were enrolled. Neutrophil and mononuclear cell apoptosis of ALL patients and the control group were studied on admission before chemotherapy and repeated at a minimum of three months after induction of chemotherapy or when the nutritional status of leukemic children improved.

RESULTS

The apoptotic functions of both ALL groups on admission were significantly lower than those of the control group. The apoptotic functions were lower in ALL patients with malnutrition than those in ALL patients without malnutrition, but this was not statistically significant. The repeated apoptotic functions of both ALL groups were increased to similar values with the control group. This increase was found to be statistically significant.

CONCLUSIONS

The apoptotic functions in ALL patients were not found to be affected by malnutrition. However, after dietary intervention, increased apoptotic functions in both ALL patient groups deserve mentioning. Dietary intervention should always be recommended as malnutrition or cachexia leads to multiple complications. Enhanced apoptosis might originate also from remission state of cancer.

Prevalence and levels of serum antibodies to gram negative microorganisms in Turkish patients with HLA-B27 positive acute anterior uveitis and controls

PURPOSE

Acute anterior uveitis (AAU), seronegative spondyloarthropathies such as ankylosing spondylitis and reactive arthritis form the group of "HLA-B27-associated diseases." The aim of this study was to analyze the prevalence and levels of serum antibodies against gram negative bacteria in Turkish patients with AAU.

METHODS

Twenty-five patients each with previously diagnosed HLA-B27 positive and negative AAU and 25 age-and sex-matched healthy control subjects were included in the study. Serum IgM, IgG and IgA antibodies to Yersiniae enterocolitica, Campylobacter jejuni and Chlamydia trachomatis were measured using enzyme linked immunosorbent assay (ELISA). Categorical data were analyzed by chi-square test. Serum levels were analyzed using the Kruskal-Wallis test.

RESULTS

The prevalence of serum IgM, IgG and IgA antibodies did not differ significantly between the HLA-B27 positive AAU, HLA-B27 negative AAU and control groups with the exception of serum IgA antibodies against Yersiniae enterocolitica. IgA antibody against Yersiniae enterocolitica was found to be more frequently positive in the control group. Comparison of serum IgM, IgG and IgA antibody levels did not significantly differ between three groups.

CONCLUSIONS

Serum antibody positivity against Yersiniae enterocolitica, Campylobacter jejuni and Chlamydia trachomatis is not frequent in the HLA-B27 positive and negative AAU patients. Serum levels of IgM, IgG, and IgA antibodies also did not show significant difference between three groups. No association between these microorganisms and the etiology of AAU was evident.

The effect of hyperthermic preconditioning on the immune system in rat peritonitis

OBJECTIVE

To assess whether hyperthermic (HT) preconditioning prevents the lethal effects of peritonitis by acting on the immune system.

DESIGN

Prospective, controlled, experimental study.

SETTING

Laboratory and animal facility of the university.

MATERIALS

Adult male Sprague-Dawley rats.

INTERVENTIONS

In the HT groups animals were subjected to hyperthermia (42 degrees C, 15 min) and 8 h later peritonitis (P) (n = 14) was induced. In the normothermic (NT) groups, animals were subjected to normothermia (38 degrees C, 15 min) and 8 h later peritonitis (n = 14) was induced. Each group had a corresponding sham laparotomy group (n = 14). Six rats from each group were allowed to live 7 days for survival. In the control group (n = 4), rats were not anesthetized or heat treated.

MEASUREMENTS AND RESULTS

Sixteen hours after peritonitis and laparotomy, rats were killed. Blood was taken to measure the percentage of CD(4)(+), CD(8)(+), CD(4)(+)CD(56)(+), CD(8)(+) CD(11 b)(+), NK(+), B cells and the level of tumor necrosis factor. Grading of peritonitis and the measurement of free oxygen radicals in the peritoneal fluid were undertaken. All rats in the HT + P and sham laparotomy groups survived for 7 days, while in the NT + P group two rats died in 7 days. HT decreased the severity of peritonitis and increased the free oxygen radicals in the peritoneal fluid; however, the difference did not reach statistical significance. HT prevented the decrease in CD(4)(+) and B cells and the increase in CD(11 b)(+).

CONCLUSIONS

HT may have a protective role in sepsis by reducing the severity of peritonitis. A causal relation between hyperthermia and an improved immune system seems possible.