Absolute CD4 count and percentage values among Libyan patients with HIV by single-platform flow cytometry.

BACKGROUND: Single-platform flow cytometry technology together with CD45-gating is becoming the method of choice for absolute CD4 T cell enumeration. Immunological assessment of HIV patients by monitoring CD4 can provide valuable information on antiviral treatment response and disease progression. METHODS: A total of 97 HIV-positive individuals were recruited from 2 hospitals in Tripoli, Libya, and 14 healthy blood donors. The HIV-infected individuals were classified by CD4+ count into HIV-positive (>200 cells/µL) or AIDS (≤200 cells/µL) groups. CD4+ and CD8+ cell counts were determined and compared among the groups and with similar published data. RESULTS: The mean ± SD CD4+ cell counts were 1106 ± 442.8 cells/µL in healthy individuals, 460 ± 219.7 cells/µL in the HIV-positive group, and 78 ± 64.3 cells/µL in the AIDS group. The mean ± SD CD4+/CD8+ ratio was 1.6 ± 0.58, 0.4 ± 0.22, and 0.1 ± 0.1, respectively. CD4+ counts in Libyan healthy adults might be higher than those reported in several studies in other regions, whereas CD4+ counts in Libyan AIDS patients seem lower. CONCLUSION: Reference values for T lymphocyte counts in Libyan healthy individuals should be investigated more extensively, and the reasons why Libyan AIDS patients seem to have such lower CD4+ counts should be examined.

Flow cytometric detection of leukemic blasts in Libyan pediatric patients with acute lymphoblastic leukemia.

The diagnosis of acute lymphoblastic leukemia (ALL), which is the most common type of cancer in children, has become more accurate with the use of flow cytometry. Here, this technology was used to immunophenotype leukemic cells in peripheral blood samples from Libyan pediatric ALL patients. We recruited 152 newly diagnosed patients at Tripoli Medical Center (Tripoli, Libya) by morphological examination of blood and bone marrow. Twenty-three surface and cytoplasmic antigen markers were used to characterize B and T cells in circulating blood cells by four-color flow cytometry. Six children (3.9%) turned out to have biphenotypic acute leukemia, 88 (57.9%) had B ALL, and 58 (38.1%) had T ALL. There were 68 cases of pro-B ALL CD10-positive (44.7%), 8 cases of pro-B ALL CD10-negative (5.2%), 6 cases of pre-B ALL (3.9%), and 6 of mature-B ALL (3.9%). CD13 was the most commonly expressed myeloid antigen in ALL. We present immunophenotypic data for the first time describing ALL cases in Libya. The reported results indicate that the most common subtype was pro-B ALL, and the frequency of T-ALL subtype was higher compared to previous studies. Six cases were positive for both myeloid and B lymphoid markers. Our findings may provide the basis for future studies to correlate immunophenotypic profile and genetic characteristics with treatment response among ALL patients.

Single ChAdOx1 nCoV-19 dose elicits stronger immune response in previously infected individuals than in SARS-CoV2 naive persons.

BACKGROUND: Current vaccines against COVID-19 effectively reduce morbidity and mortality and are vitally important for controlling the pandemic. Between December 2020 and February 2021, adenoviral vector vaccines such as ChAdOx1 (AstraZeneca-Oxford) were put in use. Recent reports demonstrate robust serological responses to a single dose of messenger RNA vaccines in individuals previously infected with SARS-CoV-2. We aimed to study the association between previous COVID-19 infection and antibody levels after a single dose of ChAdOx1 nCoV-19. METHODS: This cross-sectional study was conducted on 657 individuals who were either convalescent or SARS-CoV-2 naive and had received one dose of ChAdOx1 (AstraZeneca). A questionnaire was used to collect data on age, sex, and self-reported history of COVID-19 infection. We then compared the average levels of immunoglobulin G (IgG) between the previously infected and COVID-19-naive participants. RESULTS: We compared the antibody responses of individuals with confirmed prior COVID-19 infection with those of individuals without prior evidence of infection. The mean antibody levels in those who reported no history of COVID-19 infection were substantially lower than in those who were previously infected, in both males and females. Sex-related differences were observed when we compared antibody levels between men and women. In males, anti-S IgG antibody levels were higher in those who had been previously infected (156.1 vs. 87.69 AU/mL, p = .009), compared with the same pattern was observed in females (113.5 vs. 90.69 AU/mL, p = .005). CONCLUSIONS: Previous COVID-19 infection is associated with higher levels of SARS-CoV-2 antibodies following ChAdOx1 (AstraZeneca) vaccination. Our finding supports the notion that a single dose of ChAdOx1 nCoV-19 administered post-SARS-CoV-2 infection serves as an effective immune booster. This provides a possible rationale for a single-dose vaccine regimen for previously infected individuals.

Anti-SARS-CoV-2 IgG Antibodies Post-COVID-19 or Post-Vaccination in Libyan Population: Comparison of Four Vaccines.

Measurement of strength and durability of SARS-COV-2 antibody response is important to understand the waning dynamics of immune response to both vaccines and infection. The study aimed to evaluate the level of IgG antibodies against SARS-CoV-2 and their persistence in recovered, naïve, and vaccinated individuals. We investigated anti-spike RBD IgG antibody responses in 10,000 individuals, both following infection with SARS-CoV-2 and immunization with SARS-COV-2 AstraZeneca, Sputnik V, Sinopharm, and Sinovac. The mean levels of anti-spike IgG antibodies were higher in vaccinated participants with prior COVID-19 than in individuals without prior COVID-19. Overall, antibody titers in recovered vaccinee and naïve vaccinee persisted beyond 20 weeks. Vaccination with adenoviral-vector vaccines (AstraZeneca and Sputnik V) generates higher antibody titers than with killed virus vaccine (Sinopharm and Sinovac). Approximately two-thirds of asymptomatic unvaccinated individuals had developed virus-specific antibodies. A single dose of vaccine is likely to provide greater protection against SARS-CoV-2 infection in individuals with apparent prior SARS-CoV-2 infection, than in SARS-CoV-2-naive individuals. In addition, the high number of seropositivity among asymptomatic unvaccinated individuals showed that the number of infections are probably highly underestimated. Those vaccinated with inactivated vaccine may require more frequent boosters than those vaccinated with adenoviral vaccine. These findings are important for formulating public health vaccination strategies during COVID-19 pandemic.

Rituximab synergizes with hydroxyurea or vincristine in the killing of Ramos Burkitt's lymphoma B cell line.

Rituximab is an effective immunotherapy for CD20-positive B-cell non-Hodgkin's lymphoma. However, some patients show resistance, particularly those suffering from more aggressive lymphoma types, such as Burkitt's lymphoma. Hence, Rituximab is commonly combined with several chemotherapeutic drugs. With a view to reduce the number of such drugs, we examined the effect of combining Rituximab individually with hydroxyurea, vincristine, or etoposide on the killing of Ramos Burkitt lymphoma cell line type I. Cell death was examined by using Annexin-V/propidium iodide staining. Combining Rituximab with hydroxyurea or vincristine resulted in a synergistic effect, whereas combining it with etoposide resulted in a subadditive effect. In single treatments, the percentage of cell death ranged from 23% (Rituximab) to 36% (hydroxyurea). Combining Rituximab with hydroxyurea or vincristine resulted in a synergistic effect (83% and 74% killing, respectively). In contrast, only a subadditive effect was noticed with etoposide (36%). We conclude that the synergistic effect of Rituximab with hydroxyurea or vincristine is worthy of further study, and that further in vitro screening of chemotherapeutics might identify chemo-immunotherapeutic combinations that are effective in vivo but less toxic than currently used regimens.

Depletion of peripheral blood B cells with Rituximab and phenotype characterization of the recovering population in a patient with follicular lymphoma.

The monoclonal antibody Rituximab is useful for treatment of patients with B-cell non-Hodgkin's lymphoma. We phenotypically analyzed reconstitution of peripheral B cells in a male patient with follicular lymphoma following their depletion with Rituximab. CD19+ and CD20+ B cell counts in peripheral blood decreased rapidly following Rituximab treatment. Six months after the end of treatment, a few CD19+ B cells were detected in peripheral blood. These cells had a naive B cell phenotype (IgD+, CD27-) and they expressed high levels of CD38 and CD24, which show that the B cell pool was repopulated mainly with immature, naive B cells.