The Immune System

[msamadia1231]

You probably already know that proteins are made of amino acid units.

With immunity, think of the cells that are made of those units as lymphocytes. There is Natural Immunity and Acquired Immunity. Memorization aside, how do the names sound to you? It seems that the first is not very specific because it is a general defense against things outside, like bacteria on the table, etc.

The latter, seems specific. This specificity is mediated by antibodies and cells that make them, B lymphocytes (Humoral immunity) The other type of specific immunity, still branched from acquired is cell-mediated. If you see cell-mediated, think T-cells, cytotoxic T cells, helper T cells, suppression, natural killer cells. On these cells are receptors that help recognize antigen "markers".

Cytotoxic T cells are important for eliminating cancer cells, viral infected cells. The helper T cells produce and release cytokines. Suppressor T cells sounds exactly what it says it "suppresses" the activity of a cell.

B cells (produce antibodies) therefore involved in humoral antibody. When B cells are matured, they are referred to as plasma cells! There are different types of antibodies produced. Ig, means antibody, there is IgA, M, G, E, D.

You don't have to know the specifics, but keep in mind that IgE is a class of antibodies in allergic rxns, and promote the basophils (leukocyte) to secrete histamine. While talking about histamine, mast cells secrete lots of it.


Macrophages which are part of the natural immunity act under phagocytosis and "digest" the bacteria.They are an agranulocyte (b/c when you look under a microscope, you can't see granule shapes. They are also a leukocyte. Get ready to think about leukocytes as macrophages, basophils, eosinophils, neutrophils (pus is a combo of these and dead bacteria). The last 3 are granulocytes which are white blood cells as well and multiple nucleuses. Kind of like skeletal (multinucleated) but completely off the subject.


B and T cells all start in in the bone marrow, as well as platelets. T cells are matured in "Thymus college" and B cells depends, some in the bone marrow and others have to go through "walks" in different places to get matured; a journey you could say.

[srraghav1542]

I just wanted to add that the term leukocyte encompasses all white blood cells of the immune system. Therefore, it includes B-Cells and T-Cells, in addition to the others mentioned here (those of the innate or natural part of the immune system). B-Cells and T-Cells are collectively known as lymphocytes