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Five of the six expressed human TCR V gamma regions (V gamma 2, 3, 4, 8 and 9) can be detected by available mAb. No mAb with specificity for the remaining V gamma 5 region has been described. In this study, we have characterized mAb 56.3, which was obtained after immunization with V gamma 2/3/4/9-negative thymic gamma delta cells. V gamma transcripts were analyzed by inverse PCR and RT-PCR in 56.3+ cell lines and clones derived from peripheral blood. mAb 56.3 recognized all cells that expressed in-frame V gamma 5 transcripts. In addition, mAb 56.3 recognized some but not all cells expressing V gamma 3, but did not react with a large panel of clones expressing V gamma 2, 4, 8 or 9. In combination with anti-V gamma 2/3/4 mAb 23D12, V gamma 5-expressing cells could be clearly identified as 56.3+23D12(-). In some donors, mAb 56.3 also recognized a small fraction of TCR alpha beta cells. At the clonal level, these cells expressed in-frame V gamma 5-J beta-C beta or V gamma 3-J beta-C beta trans-rearrangements. When mAb 56.3 was combined with V gamma 2/3/4-, V gamma 8- and V gamma 9-specific mAb, all peripheral blood gamma delta T cells were stained. Thus, mAb 56.3 supplements the panel of available TCR V gamma-specific mAb. It is now possible to analyze the complete expressed human V gamma repertoire by flow cytometry.

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Background Comorbidities play a key role in severe disease outcomes in COVID-19 patients. However, the literature on preexisting respiratory diseases and COVID-19, accounting for other possible confounders, is limited. The primary objective of this study was to determine the association between preexisting respiratory diseases and severe disease outcomes among COVID-19 patients. Secondary aim was to investigate any correlation between smoking and clinical outcomes in COVID-19 patients. Methods  This is a multihospital retrospective cohort study on 1871 adult patients between March 10, 2020, and June 30, 2020, with laboratory confirmed COVID-19 diagnosis. The main outcomes of the study were severe disease outcomes i.e. mortality, need for mechanical ventilation, and intensive care unit (ICU) admission. During statistical analysis, possible confounders such as age, sex, race, BMI, and comorbidities including, hypertension, coronary artery disease, congestive heart failure, diabetes, any history of cancer and prior liver disease, chronic kidney disease, end-stage renal disease on dialysis, hyperlipidemia and history of prior stroke, were accounted for. Results  A total of 1871 patients (mean (SD) age, 64.11 (16) years; 965(51.6%) males; 1494 (79.9%) African Americans; 809 (43.2%) with ≥ 3 comorbidities) were included in the study. During their stay at the hospital, 613 patients (32.8%) died, 489 (26.1%) needed mechanical ventilation, and 592 (31.6%) required ICU admission. In fully adjusted models, patients with preexisting respiratory diseases had significantly higher mortality (adjusted Odds ratio (aOR), 1.36; 95% CI, 1.08–1.72; p = 0.01), higher rate of ICU admission (aOR, 1.34; 95% CI, 1.07–1.68; p = 0.009) and increased need for mechanical ventilation (aOR, 1.36; 95% CI, 1.07–1.72; p = 0.01). Additionally, patients with a history of smoking had significantly higher need for ICU admission (aOR, 1.25; 95% CI, 1.01–1.55; p = 0.03) in fully adjusted models. Conclusion  Preexisting respiratory diseases are an important predictor for mortality and severe disease outcomes, in COVID-19 patients. These results can help facilitate efficient resource allocation for critical care services.

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