leukocytes

antigen presenting cells (APCs)

dendritic cells very good at this, engulf antigen, break it into smaller pieces, combine with MHC marker (antigen-MHC complex), move to plasma membrane to activate cytotoxic T cells to kill the pathogen with the matching antigen

granulocytes

WBC with granules

agranulocyte

WBC without granules

eosinophils

allergic responses, phagocytic, target large pathogens (parasites and worms)

neutrophils

phagocytic, most numerous, inflammation, non specific response

basophils

inflammation, secrete histamine

monocytes

differentiate to either macrophages or dendritic cells

lymphocytes

B cells, T cells, NK cells

macrophages

phagocytic in tissue and blood, antigen presenting cells, non specific response

dendritic cells

phagocytic in skin, antigen presenting cells, bridge between non specific response and specific response, alert adaptive immune system when they detect antigens

B cells

produce antibodies, specific immune response, humoral response

T cells

specific immune response, contact and kill cells, can activate T or B cells, cellular response

natural killer (NK) cells

kill viruses and cancer cells, kill directly, only lymphocyte in non specific immune response, don’t need to be triggered by an antigen, secretes enzymes to trigger apoptosis

effector B cells/plasma cells

produce antibodies immediately

memory B cells

saved for later to make antibodies when attacked again

memory T cells

saved for later to kill cells at next invasion

effector T cells

kill cells immediately

cytotoxic T cells

specific immune response, perforins, granzymes, directly kills infected cells, (CD8+), trigger apoptosis

helper T cells

release cytokines to activate B cells or cytotoxic T cells, find antigens and trigger more cytotoxic cells, (CD4+)

effector cytotoxic T cells

directly kill cells now

memory cytotoxic T cells

directly kill cells next time

effector helper T cells

release cytokines to move other cells now

memory helper T cells

release cytokines to move other cells at next invasion