Biology Forum Human Biology Immune System

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    • #14930


      I am just wondering..again..

      I know innate and adaptive immune responses work together, but who actually does the dirty work, natural killer cells? where? phagoctyes?
      Do the complement and antibodies just kind mark the antigen for destruction?
      What is the role of T cells? just kinda recognizing foreign antigens and sending signals to other cells, making sure that other cells proliferate?
      What is the role of B cells then? to differentiate and again produce antibodies? and of course memory b cells, so that they recognise the antigen the next time? So do some B cells have antibodies on their membrane or some dont?
      Are CD4 and CD8 similar to antibodies? they kinda active T cells to recognise the antigen? wouldnt it be enough for the MHC to recognise the receptors of the T cells (TCR) ?

      Sorry lots of questions, maybe someone can help me to clarify this, to make a bigger picture 🙂

    • #104835

      I may as well make a list out of this!

      – Cell death can be due to phagocytosis or by the release of membrane perforating enzymes such as granzyme and perforin – both of these from NK or cytotoxic T-cells – that cause apoptosis.
      – Complement directly leads to the destruction of cells by causing a membrane attack complex to be formed and leading to apoptosis by creating a pore in the membrane. Antibodies can be used for tagging, but more often they just bind receptors so they’re useless or cause agglutination of invading particles etc.
      – Cytotoxic T-cells cause cell death as above, and helper T-cells collect foreign antigens so that peptide fragments from them can be presented in conjunction with MHC complexes. This allows the maturation and activation of other immune components like B-cells.
      – B-cells can differentiate into plasma cells (produce antibodies), memory cells (form germinal centres in the secondary lymphoid follicles) or B1 cells (similar role to plasma cells). Each has a single unique surface receptor.
      – CD4 and CD8 are surface glycoproteins, so not really similar to antibodies. They act as co-receptors for the TCR along with MHC, the primary function of which is to hold the two cells close together during recognition.

    • #104837

      waw thanks, that all makes more sense now 🙂

    • #104838

      You’re welcome 🙂

    • #105332

      It is a system of biological structures that defend against the infections or disease through discovering and assassinating pathogens and tumor cells…. : 🙄

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