In-depth immunophenotyping reveals significant alteration of lymphocytes in buffalo with brucellosis.

Water buffalo (Bubalus bubalis) has a prominent position in the livestock industry worldwide but still suffers from limited knowledge on the mechanisms regulating the immune against infections, including brucellosis (BRC), one of the most significant neglected zoonotic diseases of livestock. Seventy-three buffalo were recruited for the study. Thirty-five were naturally infected with Brucella spp. The aims of the study were to (i) verify the cross-reactivity of 16 monoclonal antibodies (mAbs) developed against human, bovine, and ovine antigens; (ii) evaluate lymphocyte subset alterations in BRC positive buffalo; (iii) evaluate the use of the canonical discriminant analysis (CDA), with flow cytometric data, to discriminate BRC positive from negative animals. A new set of eight mAbs (anti CD3e, CD16, CD18, CD45R0, CD79a; CD172a) were shown to cross-react with water buffalo orthologous molecules. BRC positive animals presented a significant (p < 0.0001) decrease in the percentage of PBMC (29.5 vs. 40.3), total, T and B lymphocytes (23.0 vs. 35.5, 19.2 vs. 28.9, 2.6 vs. 5.7, respectively). In contrast, they showed an increase in percentage of granulocytes (65.2 vs. 55.1; p < 0.0001) and B lymphocytes CD21neg (22.9 vs. 16.1; p = 0.0067), a higher T/B lymphocyte ratio (10.3 vs. 6.4; p = 0.0011) and CD3+ /CD21+ (14.7 vs. 8.3; p = 0.0005) ratio. The CDA, applied to 33 different flow cytometric traits, allowed the discrimination of all BRC positive from negative buffalo. Although this is a preliminary study, our results show that flow cytometry can be used in a wide range of applications in livestock diseases, including in support of uncertain BRC diagnoses.

[Hematological workup in cases of recurrent early miscarriages: what evidences?] / Bilan hématologique en cas de fausses couches précoces à répétition : quelles évidences ?

Recurrent miscarriages have a major psychological and somatic impact, as well as a significant economic burden. An etiological work-up should be offered after two or three miscarriages, the threshold varying from one scientific society to another. However, the proposed biological work-up must be justified by scientific evidence. A simple blood count, basic coagulation tests including fibrinogen assay and anti-phospholipid antibodies testing should be performed initially. Hereditary thrombophilia testing should only be carried out if there is a history of maternal thrombosis. In the event of an abnormality, management should be multidisciplinary, and the prescription of medication should follow recommended guidelines. Prophylactic treatment is not justified in the absence of a known etiology.

Les fausses couches précoces (FCP) à répétition ont un impact psychologique et somatique important, ainsi qu'un poids économique non négligeable. Un bilan étiologique devrait être proposé à partir de deux ou trois fausses couches, le seuil variant selon les sociétés savantes. Cependant, le bilan biologique doit être justifié par des évidences scientifiques. Une formule sanguine simple, des tests de coagulation de base avec le dosage du fibrinogène et une recherche d'anticorps anti-phospholipides devraient être réalisés en première intention. Une recherche de thrombophilie héréditaire ne devrait être effectuée qu'en cas d'antécédent thrombotique maternel. En cas d'anomalie, la prise en charge doit être multidisciplinaire et la prescription de médicaments doit suivre les recommandations. Un traitement prophylactique n'est pas justifié en l'absence d'étiologie retrouvée.

Comprehensive phenotyping of peripheral blood monocytes in healthy bovine.

Monocytes are bone marrow derived innate myeloid cells that circulate in the blood and play important roles in infection and inflammation. As part of the mononuclear phagocytic system, monocytes provide innate effector functions, support the adaptive immune response, and play a role in the maintenance of tissue homeostasis. In addition to their role in sensing pathogen-associated molecular patterns using several pattern recognition receptors, monocytes are characterized by their ability to ingest and kill microbes, to produce cytokines and chemokines, and to present antigens to T cells. For a long time, monocytes have been considered as a homogenous cell population, characterized by the expression of CD14, the receptor of lipopolysaccharide. Studies in several species have shown that the monocyte population consists of phenotypically and functionally different cell subsets. In this review, we report a comprehensive phenotyping of monocyte subsets in cattle. In addition, the most characterizing cell markers and gating strategies for detailed immunophenotyping of bovine monocyte subsets are discussed.

Combined effects of CXCL8 (IL-8) and CXCR2 (IL-8R) gene polymorphisms on deregressed MACE EBV indexes of milk-related traits in Simmental bulls.

CXCL8 (also known as IL-8) is a member of the CXC subfamily of chemokines that binds two of the seven transmembrane G-protein-coupled receptors (GPCRs), CXCR1 and CXCR2, to mediate and regulate leucocyte accumulation and activation at sites of inflammation. They are known to play a critical role in both disease susceptibility and infection outcome. The aim of this study was to investigate the entire sequences of CXCL8 and CXCR2 genes in thirty-one Simmental sires to evaluate the effects of genomic variants on the indexes of the bulls for milk, fat and protein yields, and for somatic cell score (SCS). Five new single nucleotide polymorphisms (SNPs) were found in CXCR2 gene. The analysis of association indicated that one SNP in CXCL8 and two in CXCR2 influenced the considered traits. To evaluate the existence of functional haplotypic effects, combinations among the three genomic variants (SNP 1 in CXCL8, SNP 6 and SNP 7 in CXCR2) were investigated. Four different haplotypic alleles were identified in the experimental population, one of which at a high frequency (61%). Bulls with Hap 4 (G-C-G at SNP 1, SNP 6, and SNP 7 respectively) had more favourable indexes for SCS (P < 0.05). These results suggest that the SNPs in CXCL8 and CXCR2 may be potential genetic markers to improve udder health in the Simmental breed.

[Janus kinase inhibitors : new perspectives for precision medicine ?] / Inhibiteurs des Janus kinases : nouvelles perspectives pour la médecine de précision ?

Janus kinase inhibitors (JAKi), such as tofacitinib, baricitinib, upadacitinib or ruxolitinib, are small molecules active on specific intracellular targets and used orally for the treatment of autoimmune or myeloproliferative diseases. Their remarkable therapeutic efficacy is offset by a significant risk of toxicities, essentially dose-dependent and a variable pharmacokinetic profile. The JAKi represent a new therapeutic armamentarium for treating autoimmune, myeloproliferative and inflammatory diseases (incl. COVID-19), but require thorough treatment individualization and close monitoring. Therapeutic Drug Monitoring (TDM) of JAKi could allow a personalized prescription and improve the efficacy-toxicity profile.

Les inhibiteurs des Janus kinases (JAKi), tels que le tofacitinib, le baricitinib, l'upadacitinib ou le ruxolitinib, représentent une nouvelle classe de petites molécules actives sur des cibles intra-cellulaires spécifiques, utilisables par voie orale pour traiter des maladies autoimmunes ou néoplasies myéloprolifératives. Leur efficacité thérapeutique remarquable est contrebalancée par un risque significatif de toxicités essentiellement dose-dépendantes et un profil pharmacocinétique variable. Les JAKi constituent une nouvelle arme thérapeutique pour le traitement des maladies autoimmunes, myéloprolifératives et inflammatoires (Covid-19), mais nécessitent une individualisation et un suivi attentifs. Le suivi thérapeutique des médicaments des JAKi pourrait permettre de personnaliser leur prescription et améliorer leur profil efficacité-toxicité.

Acquired haemophilia A in the postpartum and risk of relapse in subsequent pregnancies: A systematic literature review.

BACKGROUND: About 1%-5% of acquired haemophilia A cases affect mothers in the postpartum setting. AIMS: This study delineates the characteristics of this disease, specific to the postpartum setting, notably relapse in subsequent pregnancies. METHODS: Report of two cases and literature study (1946-2019), yielding 73 articles describing 174 cases (total 176 cases). RESULTS: Patients were aged 29.9 years (17-41) and 69% primigravidae. Diagnosis was made at a median of 60 days after delivery (range 0-308). Bleeding types were obstetrical (43.4%), cutaneous (41.3%), and muscular (36.7%). In >90% of the cases, FVIII at diagnosis was <1% (range 0%-8%). FVIII inhibitor was documented in 75.4% cases (median titre of 20 BU/ml, range 1-621). Haemostatic treatment was necessary in 57.1% using fresh frozen plasma (16%), factor concentrate (27.6%) and/or bypassing agents (37.4%). Immunosuppressive treatment was administered in 90.8%, mostly steroids (85.3%), alone or combined with immunosuppressants (27%). Rituximab was used mostly as a second line treatment. Only 24 patients (13.6%) had documented subsequent pregnancies and 6 (22.2%) suffered haemophilia recurrence during pregnancy. CONCLUSION: This study allows better definition of: (1) clinical and laboratory characteristics of postpartum acquired haemophilia, (2) response to therapy, and (3) the risk of relapse for subsequent pregnancies.

Novel SNPs and haplotypes identified in the CD4 gene and their influence on deregressed MACE EBV indexes of milk-related traits in Simmental breed.

Cluster of differentiation 4 (CD4) is the accessory protein non-covalently bound to the T cell receptor that recognizes an invariant region of MHC class II on antigen presenting cells. Its cytoplasmic tail, physically associated with a protein tyrosine kinase, is important in the activation of helper/inducer T lymphocytes. In Bos taurus, CD4 gene is located on chromosome 5 from which two isoforms are transcribed, with a different number of amino acids due to splicing of exon 7 and variation in the reading frame. The aim of this study was to investigate the sequence of the entire CD4 gene in Simmental sires to evaluate the effects of genomic variants on the indexes of the bulls for milk, fat and protein yields, as well as somatic cell score. The associations among genomic variants and indexes were analysed using the Allele and GLM procedures of SAS 9.4. The analysis indicated that only four of the thirty-one identified SNPs influenced the considered traits. Identified variants insist on coding zones and intronic sequences, where we revealed the presence of sites for transcription factors. To evaluate the existence of haplotypic effects, combinations among the four genomic variants (SNP 3, SNP 8, SNP 11 and SNP 19) were investigated. Six different haplotypic alleles were identified, but only four of them were frequent enough to allow for an evaluation of any haplotypic effect (at least six copies in the examined sample): Hap1, Hap2, Hap3 and Hap6. The analysis of associations between the selected haplotypes in the CD4 gene with milk related indexes showed that bulls with Hap2 (T-A-C-C) had better indexes for milk and protein yields (P < 0.05), whereas the presence of the Hap1 haplotype (A-G-A-T) caused a significant decrease of the index for protein yield (P < 0.05). Frequencies of the two alleles Hap1 and Hap2 (9 and 36% respectively) make them of interest for their possible inclusion in breeding schemes and support the hypothesis of considering this gene as a candidate for the improvement of milk-related traits in the Simmental breed.

Comparison of metabolic, oxidative and inflammatory status of Simmental × Holstein crossbred with parental breeds during the peripartal and early lactation periods.

The aim of the research reported in this paper was to evaluate plasma concentrations of energy, oxidative and inflammatory biomarkers of Simmental (sire) × Holstein (dam) crossbred cows, in comparison with the two parental breeds during the peripartal and early lactation periods and to estimate the effects of heterosis for these traits. Thirty-three animals, managed under the same conditions, 8 Simmental (SI), 9 Holstein (HO) and 16 crossbred (CR) cows were enrolled in this study. Glucose, non-esterified fatty acids (NEFA), ß-hydroxybutyrate (BHB), total bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), creatine kinase (CK), total protein, albumin, creatinine and urea were determined in blood sampled at six different time points (30 ± 3 and 15 ± 3 d before the expected calving date, at calving and 15, 30 and 60 d after calving). Furthermore, derived reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), interleukin-6 (IL-6), haptoglobin (Hp) and serum amyloid A protein (SAA) were determined to evaluate inflammatory and oxidative status. Results showed that the CR group had significantly lower average values of glucose and NEFA when compared to HO group; signifcantly lower values of urea than SI group and significantly higher values of creatinine than HO. Furthermore, CR cows showed the lowest average value of d-ROMs with respect to SI and HO parental breeds. Finally, the average value of haptoglobin was significantly lower in CR and HO groups, when compared to SI group. As for the heterosis we found the highest (positive) percentage for CK (98%) and BAP (47%) and the lowest (negative) percentage for OSi (-75%) and d-ROMs (-39%). A negative percentage was also found for the glucose (-11%) and NEFA (-20%) toward the Simmental parental breed. Our results suggest a different response among the three genetic groups during the peripartal and early lactation periods. In particular, CR and SI cows seem more adaptable regarding energy metabolism and oxidative status. Heterosis led to a positive effect on those parameters in Simmental (sire) × Holstein (dam) crossbred cows F1 population (50% Simmental and 50% Holstein).

[Vitamin B12 in practice: When to test ? How to test ? And who should be treated?] / Vitamine B12 en pratique : quand tester ? Comment tester ? Et qui substituer ?

Vitamin B12 deficiency is common in outpatients and inpatient populations, with potentially severe neuropsychiatric and hematological impact, which requires timely diagnosis and treatment. The different diagnostic tests all have their limitations but can be combined, sequentially. We propose to review the treatment options according to the different etiologies of the deficiency, highlighting the costs of the therapies and their coverage by the health insurance.

La carence en vitamine B12 est fréquente en médecine ambulatoire et hospitalière, avec des conséquences neuropsychiatriques et hématologiques potentiellement sévères, nécessitant un diagnostic et un traitement adéquat. Les différents tests diagnostiques ont tous leurs limitations mais peuvent être utilisés de manière complémentaire. Nous proposons de refaire un point sur les possibilités de traitement en fonction des différentes étiologies de la carence, en mettant notamment en exergue les différents coûts des thérapies et leur prise en charge par l'assurance de base.

Simmental × Holstein crossbred: comparison of immunological traits with parental breeds during peripartum and early lactation period.

The experiment described in this research communication aimed to compare the immunological traits of Simmental (sire) × Holstein (dam) crossbred cows with the two parental breeds in the peripartum and early lactation period and to estimate the effects of heterosis for these traits. Flow cytometric evaluation of leukocyte subpopulations was assessed in 16 Crossbred (CR), 8 Holstein (HO) and 8 Simmental (SI) cows. Estimated average values of innate and adaptive immune cells showed statistically significant differences between the crossbred cows and parental breeds. Interestingly, the most relevant differences between the three groups related to adaptive immune cells. In particular, the CR cows showed a lower percentage of CD3+ T lymphocytes compared with the SI group (P < 0.0001) and the highest proportions of CD21+ B lymphocytes among the three groups (P < 0.0001). Furthermore, we found the highest positive value of heterosis for the CD21+ B lymphocytes (7.0) and the lowest negative value for CD3+ T lymphocytes (-4.8) in F1 derived population. It seems reasonable to believe that these differences could affect immune function of crossbred cows.

[Hematology in the time of COVID-19]. / L'hématologie au temps du COVID-19.

The COVID-19 pandemic impacts the hematology practice. Intensive chemotherapies for high-grade lymphomas and acute leukemias, multiple myeloma treatments and most hematopoietic stem cell transplantations should be performed as usual. Low-grade lymphomas should only be treated when strictly indicated, maintenance can be postponed. Other myeloid neoplasia and their therapies cause imunosupression; dose adjustment is recommended but no brisk stopping. Sickle cell anemia patients are highly succeptible to severe COVID-19 course. Thrombocytopenia and procoagulant state are associated with severe courses of COVID-19, requiring an individualized therapy. No data indicate a risk of SARS-CoV-2 transmission through blood product transfusion.

La pandémie de COVID-19 affecte la prise en charge hématologique. Les chimiothérapies intensives pour les lymphomes agressifs et les leucémies aiguës, les traitements du myélome multiple, ainsi que la plupart des greffes de cellules souches hématopoïétiques doivent continuer à être pratiquées. Les lymphomes de bas grade seront traités uniquement avec des indications claires ; et la maintenance repoussée. Les autres néoplasies myéloïdes et leurs traitements causent une immunosuppression ; on recommande une adaptation des doses, mais pas d'arrêt brusque. La drépanocytose rend les patients très vulnérables au COVID-19. La thrombopénie signe un état procoagulant et la sévérité du COVID-19, nécessitant un traitement individualisé. Aucune donnée n'indique de risque d'une transmission du SARS-CoV-2 par transfusion de produits sanguins.

Characterization of leptin receptor gene in Bubalus bubalis and association analysis with body measurement traits.

Leptin has a pleiotropic effect on regulating appetite, energy metabolism, growth, reproduction, body composition and immunity. This property supports leptin and its receptor as candidate genes for evaluating genetic polymorphisms to associate with growth, milk yield and other economic traits. The aim of this study is to characterize the leptin receptor gene in Bubalus bubalis, to identify single-nucleotide polymorphism (SNP) sites in different coding and non-coding regions and to analyse potential associations between SNPs identified and the body measurements traits of growing buffalo heifers. A group of 64 animals were genotyped by direct sequencing and twenty-eight SNPs were detected. A sequence analysis revealed the presence of nine interesting SNPs in gene sequence. The association analysis of polymorphisms with the body measurements traits of growing buffalo heifers shows significant statistical effects on chest depth and sacrum height. Therefore according to the results obtained from this study, the leptin receptor gene appears to have potential effects on the body measurement traits of Bubalus bubalis.

Flow cytometric analysis of hepatopancreatic cells from Armadillidium vulgare highlights terrestrial isopods as efficient environmental bioindicators in ex vivo settings.

Several studies have reported the high bioindication capacity of Isopoda (Crustacea, Oniscidea), which is related to their important ability to accumulate contaminants, usefulness in soil ecotoxicology and bioindication activities. Any change in the isopod population, diversity and life cycle can indicate relevant pollution levels. The analysis of target tissues, such as the hepatopancreas, is another emerging approach (from a cytologic/histological level) to detect contaminant accumulation from different sources. In this study, tissue disaggregation procedures were optimised in the hepatopancreas, and flow cytometry (FC) was applied to detect cell viability and several cell functions. After disaggregation, two hepatopancreatic cell types, small (S) and big (B), were still recognisable: they differed in morphology and behaviour. The analyses were conducted for the first time on isopods from sites under different conditions of ecological disturbance through cytometric re-interpretation of ecological-environmental parameters. Significant differences in cell functional parameters were found, highlighting that isopod hepatopancreatic cells can be efficiently analysed by FC and represent standardisable, early biological indicators, tracing environmental-induced stress through cytologic/histologic analyses.

Flow Cytometric Identification and Enumeration of Monocyte Subsets in Bovine and Water Buffalo Peripheral Blood.

Monocytes are innate immune system key players with pivotal roles during infection and inflammation. They migrate into tissues and differentiate into myeloid effect cells (macrophages, dendritic cells) which orchestrate inflammatory processes and are interfaces between the innate and adaptive immune responses. Their clinical relevance to health and disease of cattle (Bos taurus) and water buffalo (Bubalus bubalis), two of the most important livestock species, has been highlighted in physiologic (pregnancy) and pathologic (mastitis, metritis, and viral infections) conditions. The existence of three different monocyte subsets in cattle was established by flow cytometry (FC), as follows: classical (cM; CD14++ CD16-/low ), intermediate (intM; CD14++/+ CD16+ ), and non-classical (ncM; CD14-/low CD16++ ) monocytes. FC applications for studying the immune system of cattle and water buffalo still have significant limitations. In this article, we describe some practical approaches to overcome these limitations and, in particular, allow the identification and enumeration of cM, intM, and ncM subpopulations in cattle and buffalo peripheral blood. Indeed, we propose the new procedure lyse/wash/no-centrifugation (L/W/NC) that can be combined with the FC absolute counting procedures and can overcome specific issues of the lyse/no-wash protocols (L/NW). Finally, for the first time, we demonstrated the existence of cM, intM, and ncM monocyte subsets also in the water buffalo, showing some interesting differences with cattle, such as the bubaline cM are mainly CD14+/++ /CD16+ . These subtle differences may influence inflammatory disease regulation in, for example, mastitis and metritis. The upregulation of CD16 expression on cM may reveal different monocyte priming, leading to different functional features of macrophages/dendritic cells in tissues after infection. © 2023 Wiley Periodicals LLC. Basic Protocol: Absolute count of cM, intM, and ncM without compensation Alternate Protocol: Absolute count of cM, intM, and ncM for single laser platform Support Protocol 1: In-house monoclonal antibody labeling using a Pacific Blue™ kit Support Protocol 2: In-house monoclonal antibody labeling using an Alexa Fluor® 647 kit Support Protocol 3: Titration of fluorochrome-conjugated antibodies.

Identification of High Platelet Reactivity Despite ADP P2Y 12 Inhibitor Treatment: Two Populations in the Vasodilator-Stimulated Phosphoprotein Assay and Variable PFA-P2Y Shapes of Curve.

Introduction Response to ADP P2Y 12 receptor inhibition by clopidogrel can be evaluated by various techniques. Here, we compared a functional rapid point-of-care technique (PFA-P2Y) with the degree of biochemical inhibition assessed by the VASP/P2Y 12 assay. Methods Platelet response to clopidogrel was investigated in 173 patients undergoing elective intracerebral stenting (derivation cohort n = 117; validation cohort n = 56). High platelet reactivity (HPR) was defined as PFA-P2Y occlusion time <106 seconds or VASP/P2Y 12 platelet reactivity index (PRI) >50%. Results In the derivation cohort, receiver operator characteristics analysis for the ability of PFA-P2Y to detect biochemical HPR showed high specificity (98.4%) but poor sensitivity (20.0%) and a very low area under the curve (0.59). The VASP/P2Y 12 assay revealed two coexisting platelet populations with different levels of vasodilator-stimulated phosphoprotein (VASP) phosphorylation: a fraction of highly phosphorylated, inhibited platelets and another of poorly phosphorylated, reactive platelets. Analysis of the PFA-P2Y curve shape revealed different types, categorized by time of occlusion (<106 seconds, 106 to 300 seconds, >300 seconds), and pattern (regular, irregular, and atypical). Noteworthy, curves with late occlusion and permeable curves with an irregular or atypical pattern correlated with VASP-PRI >50% and smaller sizes of the inhibited platelet subpopulation. Considering the PFA-P2Y shape of the curve for the detection of HPR improved sensitivity (72.7%) and preserved specificity (91.9%), with a rather high AUC (0.823). The validation cohort confirmed the VASP/P2Y 12 assay data and the usefulness of considering the PFA-P2Y curve shape. Conclusion In patients treated with acetylsalicylic acid and clopidogrel for 7-10 days, the VASP/P2Y 12 assay reveals two coexisting subpopulations of differentially inhibited platelets, whose relative sizes predict global PRI and distinct PFA-P2Y curve patterns, indicating incomplete clopidogrel efficacy. The detailed analysis of both VASP/P2Y 12 and PFA-P2Y is necessary for optimal detection of HPR.

Hyperthermia-induced changes in leukocyte survival and phagocytosis: a comparative study in bovine and buffalo leukocytes.

Heat stress negatively affects health, welfare, and livestock productivity by impairing immune function, increasing disease incidence. In recent years, there has been increasing interest in understanding the immune system of water buffalo due to the growing economic impact of this species for the high quality and nutritional value of buffalo milk. While there are common responses across bovine and buffalo species, there are also some species-specific variations in the physiological responses to heat stress, mainly attributed to differences in metabolism and heat dissipation efficiency. At cellular level, the exposure to thermal stress induces several anomalies in cell functions. However, there is limited knowledge about the differential response of bovine and buffalo leucocytes to early and late exposure to different degrees of thermal exposure. The aim of this study was to compare the in vitro effect of hyperthermia on apoptosis and phagocytosis in leukocytes from bovine and buffalo species. For this, whole blood samples of six bovines and nine buffaloes were incubated at 39°C (mimicking normothermia condition) or 41°C (mimicking heat stress condition) for 1, 2, and 4 h. Two flow cytometric assays were then performed to evaluate apoptosis and determine functional capacity of phagocytic cells (neutrophils and monocytes). The results showed that the viability of bovine and buffalo leukocytes was differently affected by temperature and time of in vitro exposure. A higher percentage of apoptotic leukocytes was observed in bovines than in buffaloes at 39°C (3.19 vs. 1.51, p < 0.05) and 41°C (4.01 vs. 1.69, p < 0.05) and for all incubation time points (p < 0.05). In contrast, no difference was observed in the fraction of necrotic leukocytes between the two species. In both species, lymphocytes showed the highest sensitivity to hyperthermia, showing an increased apoptosis rates along with increased incubation time. In bovine, apoptotic lymphocytes increased from 5.79 to 12.7% at 39°C (p < 0.05), in buffalo, this population increased from 1.50 to 3.57% at 39°C and from 2.90 to 4.99% at 41°C (p < 0.05). Although no significant differences were found between the two species regarding the percentage of phagocytic neutrophils, lower phagocytosis capacity values (MFI, mean fluorescence intensity) were found in bovines compared with buffaloes at 41°C (27960.72 vs. 53676.45, p > 0.05). However, for monocytes, the differences between species were significant for both phagocytosis activity and capacity with lower percentages of bovine phagocytic monocytes after 2 h at 39°C and after 1 h at 41°C. The bovine monocytes showed lower MFI values for all temperature and time variations than buffaloes (37538.91 vs. 90445.47 at 39°C and 33752.91 vs. 70278.79 at 41°C, p < 0.05). In conclusion, the current study represents the first report on the comparative analysis of the effect of in vitro heat stress on bovine and buffalo leukocyte populations, highlighting that the leukocytes of buffalo exhibit relatively higher thermal adaptation than bovine cells.