The number of

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typically increases in response to bacterial infections.

A. Basophils: Basophils are involved in allergic and inflammatory responses (release histamine/heparin) and typically do not increase markedly in typical bacterial infections.
B. Monocytes: Monocytes can increase in chronic or certain infections and differentiate into macrophages, but they are not the first-line increase seen in acute bacterial infections.
C. Neutrophils: Neutrophils are the primary responders to acute bacterial infections and typically increase (neutrophilia) during bacterial invasion.
D. Eosinophils: Eosinophils increase mainly with parasitic infections and allergic reactions, not typically with bacterial infections.
E. Erythrocytes: Erythrocyte (RBC) counts do not typically increase in response to acute bacterial infection; if anything, severe/chronic disease may lower RBC counts.

A. AB, Rh-negative: AB RBCs carry both A and B antigens, so they cannot serve as universal RBC donors (but AB plasma is often considered a universal plasma donor).
B. O, Rh-negative: O negative RBCs lack A, B, and Rh (D) antigens, so they are the universal donor for red blood cell transfusions.
C. AB, Rh-positive: AB positive RBCs have A, B, and Rh antigens and therefore are not universal RBC donors.
D. O, Rh-positive: O positive RBCs lack A and B antigens but express Rh (D) antigen, so they can’t be given safely to Rh-negative recipients; therefore they are not fully universal donors.