Humoral immunity is associated with B-cells.

Introduction:
The immune system is responsible for defending the body against external pathogens such as bacteria, viruses, and fungi. The immune system has two major types of immunity, including humoral and cell-mediated immunity. Humoral immunity is a type of adaptive immunity that is mediated by the production of antibodies by B-cells.

B-cells:
B-cells are a type of white blood cell that is responsible for producing antibodies. Antibodies are proteins that are produced by B-cells in response to the presence of foreign antigens. B-cells have receptors on their surface that can recognize specific antigens. Once a B-cell recognizes an antigen, it undergoes a process of activation, proliferation, and differentiation into antibody-secreting cells called plasma cells.

Antibodies:
Antibodies are proteins that are produced by B-cells in response to the presence of foreign antigens. Antibodies have a Y-shaped structure that consists of two heavy chains and two light chains. The tips of the Y-shaped structure contain antigen-binding sites that can recognize specific antigens. Once an antibody binds to an antigen, it can neutralize the antigen or mark it for destruction by other cells of the immune system.

Humoral immunity:
Humoral immunity is a type of adaptive immunity that is mediated by the production of antibodies by B-cells. Humoral immunity is effective against extracellular pathogens such as bacteria and viruses that are circulating in the blood or lymphatic system. In humoral immunity, B-cells recognize foreign antigens and produce antibodies that can neutralize the antigens or mark them for destruction by other cells of the immune system.

Conclusion:
In conclusion, humoral immunity is associated with B-cells. B-cells are responsible for recognizing foreign antigens and producing antibodies in response to the antigens. Antibodies can neutralize or mark the antigens for destruction by other cells of the immune system. Humoral immunity is effective against extracellular pathogens such as bacteria and viruses.