Cell Biology
Adaptive immune response
The adaptive immune response is the antigen-specific arm of vertebrate immunity mediated by B and T lymphocytes. It is characterized by exquisite specificity, clonal expansion, immunological memory, and regulation that together provide durable protection following infection or vaccination.
B cell
B cells, or B lymphocytes, are a class of white blood cells central to humoral immunity, producing antibodies after antigen recognition and activation. In mammals they develop primarily in the bone marrow, whereas the term “B” historically derives from the avian bursa of Fabricius where they were first defined. Through processes such as V(D)J recombination, class-switch recombination, and somatic hypermutation, B cells generate diverse and high‑affinity antibody responses, form immune memory, and contribute to antigen presentation.
Major histocompatibility complex
The major histocompatibility complex (MHC) is a multigene region in jawed vertebrates that encodes cell-surface glycoproteins central to antigen presentation and T-cell recognition. In humans, the MHC is termed the Human Leukocyte Antigen (HLA) system and resides on chromosome 6p21, encompassing class I, class II, and class III gene clusters that govern adaptive immunity, natural killer cell regulation, and complement components. Extensive polymorphism across classical HLA loci underlies interindividual variation in immune responses, disease associations, and transplantation compatibility.
Osmosis
Osmosis is the spontaneous movement of a solvent through a semipermeable membrane from a region of higher solvent chemical potential (lower solute concentration) to lower solvent chemical potential (higher solute concentration). It is fundamental in physical chemistry and cell biology, underpinning water balance in cells and enabling technologies such as reverse osmosis desalination and dialysis.
T cell
T cells, or T lymphocytes, are white blood cells that mediate cellular immunity within the adaptive immune system. Originating in the bone marrow and maturing in the thymus, they recognize antigens via T cell receptors and execute diverse functions including cytotoxic killing, immune regulation, and coordination of responses through helper subsets.