An immune phagocyte engulfs a microbe, processes its proteins, and displays peptide on class II MHC to a CD4+ lymphocyte. Which cell performed this role?

After clonal expansion in a lymph node, one type of B-cell daughter stops dividing and secretes large amounts of immunoglobulin into lymph and blood. Which cell is it?

A CD4+ lymphocyte recognizes antigen on class II MHC and releases cytokines that stimulate both B-cell cloning and other lymphocytes. Which cell is acting?

A body cell infected by a virus displays foreign peptide on class I MHC, then receives death signals from an antigen-specific lymphocyte. Which cell sends those signals?

A lymphocyte with matching surface immunoglobulin binds free antigen, receives cytokine help, and gives rise to antibody-secreting daughters. Which lymphocyte is it?

After the first response contracts, a long-lived daughter remains in lymphoid tissue and can rapidly restart antibody production later. Which cell is it?

A long-lived lymphocyte from the first viral response persists and can quickly make cytokines or cytotoxic daughters when its antigen returns. Which cell is it?

Virus particles are coated so their attachment sites cannot bind host-cell receptors. What action has the bound immunoglobulin performed?

Several bacteria are cross-linked into one large clump after immunoglobulins attach to repeated surface antigens. What action is occurring?

A coated bacterium is easier for a macrophage to grab because Fc regions bind phagocyte receptors. What action is this?

Antibodies attach to a bacterial surface, and a plasma protein cascade assembles a membrane attack complex there. What action started the cascade?

Soluble antigen molecules are cross-linked into large insoluble complexes that settle out of body fluid. What antibody action is this?

A parasite is too large for a macrophage to engulf, so antibodies coating its surface instead attach by their Fc region to a natural killer cell, which then kills the parasite with cytotoxins. What antibody action is this?

A macrophage has processed a swallowed microbe and displayed peptide on class II MHC. What event comes next to activate the specific CD4+ response?

A lymphocyte with matching surface immunoglobulin has bound antigen and received cytokines from a CD4+ cell. What process immediately increases the matching clone?

In a first exposure, what must occur before a naive B lymphocyte can become a plasma cell?

After the selected B-cell clone has expanded during a primary response, which daughter cells appear so antibody level in blood can rise?

Pathogen levels fall after the first wave of effector cells and antibodies clears most antigen. What stage comes next in the primary response?

As an antigen-selected B-cell clone multiplies during a primary response, its daughters do not all take the same fate. Which outcome describes this split?

A person meets the same virus months after recovery and clears it before becoming very sick. What change from the first response explains this?

A booster dose causes antibody titer to rise sooner and higher than the original shot. Which population produced that secondary pattern?

On a second exposure to the same antigen, antibody appears after a shorter lag period. What feature of adaptive immunity causes this?

A virus returns with a major change in the surface antigen recognized during the first infection. What is the likely consequence?

Compared with the first exposure, how does antibody concentration usually change during a second exposure to the same antigen?

A newborn has antibodies that crossed the placenta from the mother, yet this protection fades within a few months. Why does it not last?